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Prelims, contents etc Acro 18/7/97 8:06 Page i
T
H
E
G
E
N
E
R
A
O
F
ARACEAE
S J M ayo
J Bogner
P C Boyce
Prelims, contents etc Acro 18/7/97 8:06 Page iii
T
H
E
G
E
N
E
R
A
O
F
ARACEAE
S J M ayo
J Bogner
WITH CONTRIBUTIONS FROM
J.C. French and R. Hegnauer
ILLUSTRATIONS BY
E. Catherine
P C Boyce
Prelims, contents etc Acro 18/7/97 8:06 Page iv
© Copyright The Trustees, Royal Botanic Gardens, Kew
First published 1997
ISBN 1 900347 22 9
Cover design by John Stone
Book design by Jeff Eden
Page make-up by Media Resources,
Information Services Department,
Royal Botanic Gardens, Kew
Printed in The European Union by
Continental Printing, Belgium.
Prelims, contents etc Acro 18/7/97 8:06 Page v
C O N T E N T S - TO R E T U R N TO T H I S PA G E P R E S S C
Dedication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vii
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
Preface
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
A
GENERAL PART
1. History
.......................................................................2
2. Vegetative Morphology
...........................................................6
3. Vegetative Anatomy (by J.C. French)
.................................................9
4. Inflorescence and Floral Morphology
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5. Inflorescence and Floral Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6. Fruits and Seeds
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
7. Seedling Morphology
8. Embryology
9. Cytology
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
10. Palynology
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
11. Phytochemistry and Chemotaxonomy (by R. Hegnauer)
12. Ecology and Life Forms
13. Pollination Biology
14. Dispersal
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
15. Geography
16. Uses
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
17. Cultivation
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
18. Conservation
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
19. Fossil Record
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
20. Phylogenetic relationships within the Monocotyledons
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
21. Phylogenetic relationships within Araceae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
22. Previous classifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
CONTENTS
v
Prelims, contents etc Acro 18/7/97 8:06 Page vi
CONTENTS
B
TAXONOMIC PART
23. Synopsis of the Classification of Araceae
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
24. Family Description of Araceae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
25. Key to the Genera of Araceae and Acoraceae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
26. Descriptions of the Tribes and Genera of Araceae
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
27. Description of Acoraceae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
28. References and selected taxonomic literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
29. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30. Appendix:
Table 9. Fungal Parasites . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 10. Schott’s (1860) classification of Aroideae . . . . . . . .
Table 11. Engler’s (1876b) classification of Araceae . . . . . . .
Table 12. Engler’s (1920b) classification of Araceae . . . . . . .
Table 13. Grayum’s (1990) classification of Araceae . . . . . . .
Table 14. Bogner & Nicolson’s (1991) classification of Araceae
Table 15. Generic country lists . . . . . . . . . . . . . . . . . . . . . . .
Table 16. Colour plates: photo credits and vouchers . . . . . . .
31. Index to scientific names . . . . . . . . . . . . . . . . . . . . . . . . . . .
32. Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
33. Descriptions of new taxa . . . . . . . . . . . . . . . . . . . . . . . . . . .
Colour Plates
vi
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318
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THE GENERA OF ARACEAE
Prelims, contents etc Acro 18/7/97 8:06 Page vii
C
D E D I C AT I O N
We dedicate this book to the memory of Heinrich
Wilhelm Schott and Heinrich Adolf Gustav Engler, the
two great founding fathers of Araceae systematics, and
also to Nicholas Edward Brown, whose studies of the
family, while less widely known, were of the highest
standard.
DEDICATION
vii
Prelims, contents etc Acro 18/7/97 8:06 Page viii
F O R E WO R D
C
By Dan H. Nicolson
It has been almost 150 years since H.W. Schott published his monumental Genera Aroidearum (The
Genera of Araceae). A new treatment of the family has
been a desideratum for a century and urgently needed
during the last fifty years. What has been particularly
needed is an illustrated work that can be used by anyone to recognize unknowns and help learn the terms
necessary for accurate understanding of the taxa.
It is often taken for granted that the family is more
or less completely known and information is readily
available. The first problem is that the keystone works
by Schott (1794-1865) and Engler (1844-1930) are
expensive, if available for purchase, and not to be
found in public libraries. If you are fortunate enough
to find them, you discover the second problem. They
are in Latin!
In spite of such problems there has been a revival
of interest in the family. An astonishing number of
workers have been studying plants in the field and cultivation and applying new and sophisticated techniques.
New tools, such as the scanning electron microscope
(which revolutionized comparative study of pollen) and
techniques, such as molecular systematics and cladistics,
have revolutionized thinking about relationships.
At last it has been possible to stimulate three people, scarcely more than entering middle life and with
all the necessary modern training, to collaborate and
synthesize what is known about the genera of Araceae,
including at least one crisp, fresh and new full page
drawing of each genus. Comparison of this work with
its predecessor shows the distance we have travelled.
Do not think that the last word has been spoken.
New species, even genera, are still turning up and
some of them are testing the hypotheses that we wish
were facts.
Smithsonian Institution, Washington, D.C.
March 1994
viii
THE GENERA OF ARACEAE
Prelims, contents etc Acro 18/7/97 8:06 Page ix
C
P R E FA C E
The Araceae, or aroids, are plants which are very familiar to everyone but paradoxically little known.
Monstera deliciosa, Epipremnum pinnatum ‘Aureum’
(syn. Epipremnum aureum), Philodendron scandens,
Dieffenbachia maculata and Aglaonema commutatum may be counted as among the world’s most
popular house plants. But most rarely flower in their
domestic environment, and the fact that they are all
aroids is appreciated by relatively few people. Once
their inflorescences appear, however, it is obvious they
belong together, with their characteristic cowl-like
spathe and central, fleshy spike, known as the spadix.
The most familiar aroid inflorescences are those of
Anthurium andraeanum and Zantedeschia aethiopica,
which are used the world over as cut flowers.
The family is extraordinarily diverse in appearance,
with the foliage being probably its most widely appreciated feature. The perforated leaf of Monstera deliciosa
(the subject of our cover) is one of the most instantly
recognizable plant images the world over, while the
velvet, pendent leaves of Anthurium waroqueanum
are unforgettably elegant. The beauty of many other
genera, such as Philodendron, Alocasia and Arisaema
is also very largely due to their superb foliage. In sharp
contrast, the inflorescences of certain aroids are quite
repulsive; that of Helicodiceros muscivorus, for example, resembles nothing so much as the rear end of a
decomposing mammal corpse, while so bizarre is the
foul-smelling Amorphophallus konjac that some years
ago it was chosen as the basis for a film dramatization
of the “triffids” of science fiction. Towering over all
such lesser monstrosities is Amorphophallus titanum,
one of the vegetable wonders of the world, which
attracts large crowds at botanic gardens when from
time to time the great tuber yields a huge phallic inflorescence smelling of rotten fish.
Why is it then, that aroids are not better known as
a plant group? We think the reason is a dearth of accessible literature. Apart from Deni Bown’s excellent
“Aroids. Plants of the Arum Family”, published in 1988
for the non-specialist reader, there have been no general and comprehensive treatments of the Araceae,
either technical or lay, since the publication of Engler’s
taxonomic monograph (in Latin and German) for his
“Das Pflanzenreich” series in the first two decades of
this century. We have tried to contribute towards filling this gap with a general taxonomic treatment of the
family which extends to the level of genus. While it is
unashamedly technical, and may seem somewhat forbidding to the general reader, we hope that the book’s
publication will encourage more people to study and
enjoy these wonderful plants, which are among the
most beautiful and dramatic that the vegetable kingdom has to offer.
The idea for this book germinated in 1980 when the
first international workshop on the systematics of
Araceae was held at the Marie Selby Botanical Garden,
Sarasota, Florida, organized by Dr Michael Madison.
Madison and Simon Mayo began a manuscript but the
project never came to fruition. In 1987, with the encouragement of Professor Grenville Lucas, then Keeper of the
Kew Herbarium, Mayo and Josef Bogner of the Munich
Botanic Garden resolved to tackle the task anew and
Peter Boyce joined us soon afterwards. Eleanor
Catherine, the artist, completed the team at a later stage.
The format of this book is modelled on that of the
Genera Palmarum by Dr Natalie Uhl and Dr John
Dransfield. The delimitation of all the genera has been
critically re-examined in the light of modern studies.
Since A. Engler’s last monograph in “Das Pflanzenreich”
various new genera have been described and old ones
reduced to synonymy. F. Gagnepain described
Pycnospatha from Thailand, H. Jumelle Arophyton and
Carlephyton from Madagascar and S. Buchet
Colletogyne, also from Madagascar. M. Hotta contributed four new genera, Heteroaridarum,
Pedicellarum and Phymatarum from Sarawak, and
Furtadoa from Sumatra and the Malay Peninsula. D.H.
Nicolson and colleagues contributed Bognera and
Filarum from tropical America and Hottarum from
Borneo. G.S. Bunting described the extraordinary
aquatic Jasarum, and Lasimorpha, a synonym of
Cyrtosperma according to Engler, has been reestablished by A. Hay. Hay also recently described
Anaphyllopsis from tropical America and Lazarum from
Australia. Despite these changes, the total number of
genera treated here (105 without Acorus) is much the
same as that presented by Engler (108 without Acorus).
Cladistic analysis of morphological and molecular data
in recent years has, however, meant that the classification has changed considerably since Engler’s time.
We have deliberately laid the primary emphasis on
the preparation of completely revised descriptions of
the genera, together with analytical illustrations for
each. The plates are all original drawings by Eleanor
Catherine, based on a combination of herbarium, spirit
(from the Kew spirit collection) and living specimens,
supplemented when necessary by photographs. The
chapters of the General Part are intended to be summaries, in some cases quite brief, of various aspects of
Araceae which are of taxonomic and general interest.
In two cases, the treatments are much more detailed,
namely chapter 3 on vegetative anatomy, and chapter
11 on phytochemistry and chemotaxonomy, which we
P R E FA C E
ix
Prelims, contents etc Acro 18/7/97 8:06 Page x
were very fortunate to receive from Professor J.C.
French and Professor R. Hegnauer, respectively. Their
contributions are the first detailed modern reviews in
English of these subjects for the Araceae .
We have omitted any general treatment of the molecular systematics of the family, which is being studied,
in particular, by Professor French and his colleagues at
Rutgers University, New Jersey. They have generously
allowed us access to their most important phylogenetic conclusions, thus greatly improving our
discussion of the family’s phylogeny (chapter 21).
We have included material on Acorus, including a
generic treatment, despite the fact that we accept that
this genus does not belong to the Araceae. However,
it was felt that it would be convenient to the non-specialist reader, who might expect to find something on
x
THE GENERA OF ARACEAE
the genus in a general treatment of aroids.
In contrast, we have not included any systematic
account of the Lemnaceae, which according to the
molecular work of French and colleagues, seem clearly
to be embedded within the Araceae (see chapter 20).
Our reasons are again pragmatic. The taxonomy of the
Lemnaceae has been comprehensively revised in recent
years by Professor E. Landolt and French’s results
became available only in the final stages of preparation
of this book.
Throughout the text we have employed the terms
“aroid” and “araceous” as synonymous adjectives referring to any member of the family, and the noun
“aroid” likewise. The reader should therefore not interpret “aroid” as referring only to members of the
subfamily Aroideae.
Prelims, contents etc Acro 18/7/97 8:06 Page xi
C
A C K N OW L E D G E M E N T S
A book of this kind cannot be prepared without the
help of many people besides the authors.
Our greatest debt is to Eleanor Catherine, whose
professionalism, patience and superb facility in line
illustration has produced such a unique and wonderful set of plates. It is likely that her work will be the
most valuable contribution that this book can make to
advancing knowledge of the Araceae and it is no exaggeration to say that all aroid-lovers are in her debt.
The growth of activity in aroid systematics in recent
decades has been notable for the friendly spirit of collaboration that has always prevailed and because of
this we have been able to call on the help of many
other specialist colleagues. To all these we are
extremely grateful. Dr Dan H. Nicolson undertook the
task of reviewing our manuscript and contributing a
foreword. The generic descriptions have been revised
by the following specialists who have been very generous in allowing us to use unpublished manuscripts
and in providing new data and insights on taxa and
character fields concerning which their knowledge is
much more profound than our own:- Mr Julius Boos,
Dr Thomas B. Croat, Professor James C. French, Dr
Michael H. Grayum, Dr A. Hay, Professor R. Hegnauer,
Mr Wilbert Hetterscheid, Professor Niels Jacobsen, Dr
Z. Kvaček, Dr Gitte Petersen, Professor Robin Scribailo,
Dr Mikhail Serebryanyi, Dr Elke Seubert, Dr M.
Sivadasan, Professor Thomas Stützel, Dr Sue
Thompson, Professor Hans-Jürgen Tillich and Dr
Guanghua Zhu. Professor Tom Ray contributed new
data on shoot organization. These contributions have
greatly enriched this book, but its shortcomings are
necessarily our responsibility alone.
We would also like to thank the following staff
members of the Royal Botanic Gardens, Kew, who,
among many others, provided essential support:Professor Ghillean T. Prance, Dr Charles Stirton,
Professor Grenville Lucas, Dr Michael Lock, Dr John
Dransfield, Dr Phillip Cribb, Miss Mary Gregory, Mr
Milan Svanderlik, Mr Jeff Eden, Mrs Christine Beard,
Dr Geoff Kite, Mrs Margaret Newman, Mr John Stone,
Mr John Woodhams, Mr Michael Marsh, Mr John Hale,
Mr John Norris, Mr Phillip Brewster.
It is also a pleasure to thank Cássia Mônica
Sakuragui for preparing the original maps.
We are very grateful to the directors and staff of the
following herbaria for lending us material:- A, AAU, B,
BK, BKF, BM, BO, BRUN, C, DNA, E, FI, G, HRB, K,
KEP, L, LE, M, MO, NY, P, SAN, SAR, SEL, SGN, SI, U,
US, YUKU, YUNU.
J. Bogner wishes to thank the Directors of the following institutes for financial support: the Smithsonian
Institution (Washington DC, USA) for a field study in
Sarawak, the Centre National de la Recherche
Scientifique (CNRS, Paris, France) for the publication
of the Araceae for “Flore de Madagascar et des
Comores” and the Royal Botanic Gardens, Kew (UK)
for visits to RBG Kew in connection with the preparation of this book.
The living plants used in the preparation of this
book were cultivated at the Botanischer Garten Munich
and the Living Collections Department of the Royal
Botanic Gardens, Kew and we are very grateful to the
Curators and staff of these institutes for their helpful
collaboration.
Other colleagues should be mentioned who have
prepared the ground in some important way; Deni
Bown for her splendid pioneering book “Aroids: Plants
of the Arum family”, Dr George Bunting, who was
responsible for starting the modern renaissance in aroid
systematics, Dr Michael Madison, Mrs Betty Waterbury
and Mrs Libby Besse who with their friends and colleagues, started the International Aroid Society and its
excellent journal Aroideana, and finally Professor P.B.
Tomlinson who provided the impetus for continuing
the international workshops on Araceae by organizing
the second (Harvard Forest 1984) and leading the third
(Berlin 1987) meetings.
ACKNOWLEDGEMENTS
xi
1-22 Section A Acro 18/7/97 8:00 Page 1
A
GENERAL
1-22 Section A Acro 18/7/97 8:01 Page 2
1
C
H I S TO RY
The word “arum” is derived directly
some of the finest botanical artists of
from ancient Greek “aron” and indithe day (Riedl & Riedl-Dorn 1988).
vidual species of the Araceae have
The pencil drawings are of herbeen recorded by many botanists
barium specimens and material
and historians since those ancient
preserved in alcohol from
times. Theophrastus (ca.
herbaria all over Europe and
371–285 B.C.) recorded Arum
the water colour plates were
in his treatise (Prime 1960),
painted from living plants
and Hernandez (1790)
grown at Schönbrunn, the
described a number of tropiimperial gardens near Vienna.
cal aroids and their uses by
The colour plates represent
Aztec people. European
each plant in astonishing
Araceae were described in
detail and thoroughness and
detail by botanists such as
are among the most impresFuchs (1542) and Ray (1686)
sive analyses ever achieved in
while R. Dodoens (1574)
the medium of botanical illusarranged all Araceae known to
tration. Only relatively few
him into a single group.
were
published
(Schott
J. P. de Tournefort (1700)
1853–1857, 1857, 1858, Peyritsch
created a “class” without a name
1879). Today the Icones are part
which grouped three European
of the collections of the Vienna
genera (Arum, Dracunculus and
Natural History Museum. About 80
Arisarum), characterized by the posplates (including subfamily Lasioideae)
session of a “monopetalous” flower.
are lost, while Schott’s herbarium of
This concept of the aroid infloresAraceae, consisting of 1379 specicence as a flower with a single petal
mens, was destroyed at the end of
Figure 1. H.W. Schott (1794–1865).
also influenced Linnaeus (1753,
the Second World War (Schott 1984,
Photograph c. 1860.
1754) who classified the known
Riedl & Riedl-Dorn 1988).
species according to his artificial
Schott’s most important works
sexual system. It was not until later that the infloreswere the account of Araceae in the Meletemata botancence was recognized as a spike (spadix) of tiny
ica (Schott 1832), the Genera Aroidearum (Schott 1858)
flowers surrounded by an often colourful bract
and the Prodromus systematis Aroidearum (Schott
(spathe). A.L. de Jussieu (1789) established the Araceae
1860). Some of his new genera were first published in
as a natural family but recognized only a few small or
the cultural periodical Wiener Zeitschrift für Kunst,
rather broadly conceived genera, probably because of
Literatur, Theater und Mode as part of a series of articles
the paucity of good material of non-European taxa.
entitled Für Liebhaber der Botanik (Schott 1829a–e,
All the climbing species were grouped under the name
1830). He also published many papers on Araceae in the
Pothos and most of the terrestrial species were placed
Oesterreiches Botanisches Wochenblatt, which later
in the genera Arum and Dracontium.
became the Oesterreichische Botanische Zeitschrift (from
Modern systematic studies of the Araceae began
1858, the 8th volume, onwards).
with the work of the Austrian botanist and gardener
Schott described many new genera and species
Heinrich Wilhelm Schott. He was the first monographer
and created the first major natural classification of the
of the family and the first botanist to make careful
whole family. Though his taxon concepts were narcomparative studies of aroid inflorescences, flowers
row, many of his genera and species have withstood
and fruits. Using these observations he was able to
the test of time. He created the basis of Araceae taxput the family on a sound taxonomic footing. His work
onomy, not only for Engler, who soon followed him
is documented in his writings (Riedl 1965a, b) and by
in studying the family comprehensively, but also for
an outstanding archive of scientific illustrations (Schott
succeeding generations. A notable aspect of Schott’s
1984). This consists of a collection of 4400 superb
work was that he used a combination of herbarium
coloured and black and white plates of Araceae, the
material, living plants and field work in the study of a
Icones Aroidearum, which were prepared at his direclargely tropical plant group at a time when such a
tion and personal expense and employed the talents of
wide-ranging approach was most unusual.
2
THE GENERA OF ARACEAE
1-22 Section A Acro 18/7/97 8:01 Page 3
Riedl (1965a, b, pers. comm.)
Other significant works on the
has given details of Schott’s life
family published during Schott’s
and work. He was born on 7th
lifetime include Kunth’s treatment
January 1794 in Brünn in
for his Enumeratio Plantarum
Moravia (now Czech Republic).
(Kunth 1841), which was the first
At the age of seven he moved to
post-Linnean treatment at species
Vienna, where his father had
level, and Blume’s Rumphia
become head gardener at the
(Blume 1836–1837), which was
botanical garden of the
important especially for Asian
University. There he soon came
genera and included very fine
into contact with eminent
coloured plates.
botanists. N. von Jacquin stimuThe second great monographer
lated and directed the early
of Araceae was Adolf Engler.
interest of the boy to study
Right from the start he established
plants and once, when severely
himself as an authority on the
ill as a youth, he received a visit
family by a series of prodigious
from Alexander von Humboldt
works. His first major publication
which made a lifelong impreson the family outlined a new syssion upon him.
tem on phylogenetic lines (Engler
The young Schott attended
1876b) which was substantially
lectures in botany and other
different from Schott’s classificadisciplines (agriculture, chemtion, especially at the higher
istry) at the University, but his
ranks. The following year he prefirst employment was as an
sented a pioneering comparative
assistant gardener under the
study of araceous shoot organidirection of his father. In 1815
zation, based on original
he became gardener for the colobservations (Engler 1877). His
Figure 2. H.A. Engler (1844–1930).
lection of Austrian flora at the
treatment of Araceae for Martius’s
Photograph taken when Engler was
Belvedere Palace. Then, at von
Flora Brasiliensis followed
nineteen years old.
Jacquin’s recommendation he
(Engler 1878), and immediately
was chosen to become a parafterwards a comprehensive
ticipant in the famous Austrian-Bavarian
monograph at species level for the entire
scientific expedition to Brazil which
family appeared in De Candolle’s
included the botanist Mikan, the
Monographiae Phanerogamarum
zoologist Natterer, the mineralogist
(Engler 1879). His account for
and botanist Pohl, the botanist
Beccari’s Malesia (Engler 1883a)
C.F.P. von Martius and zoologist
was followed by the family treatJ. von Spix.
ment for Die natürlichen
Between 1817 and 1821 he
Pflanzenfamilien (Engler 1887–
worked in Brazil as a member
1889). At about this time he
of this group of naturalists and
also published two papers in
made acquaintance with a
the Botanische Jahrbücher
rich tropical flora (Schreiber
which further developed his
1822). His main duty was to
phylogenetic interpretations
establish a garden in Rio de
of morphological and anatomJaneiro to prepare plants for
ical trends in the Araceae
the long journey to Europe.
(Engler 1883b, 1884).
When he returned to Vienna
With the initiation of the
in 1821 he took up gardening
Das Pflanzenreich series in
again, eventually rising to
1900, Engler embarked on his
become the Director of the
second monograph of the entire
botanical and zoological gardens
family, completed in 1920 (Engler
at the imperial palace of Schön1905, 1911, 1912, 1915, 1920a,
brunn, a position he held until his
1920b, Engler & Krause 1908, 1920,
death on 5th March 1865. Schott was
Krause 1908, 1913) with the help of his
made a Doctor “honoris causa” and
assistant Kurt Krause (1883–1963). Engler
a member of the Kaiserliche
and Krause doubled Schott’s total
Akademie der Wissenschaften for
of about 900 species to around
Figure 3. H.A. Engler in
his later years
his work in botany and horticulture.
1800. An important feature of this
H I S TO RY
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1-22 Section A Acro 18/7/97 8:01 Page 4
treatment was the large number of
institute. He was by now an extremely
illustrations, prepared by J. Pohl.
able organizer and under his direcThese are mostly original but
tion a new botanical garden and
some were copied from Schott’s
botanical museum were planned
illustrations. The large living
and built at Dahlem, then on
collection of Araceae at the
the outskirts of Berlin. Started
Botanischer Garten Berlinin 1897, the new garden was
Dahlem was an important
inaugurated in 1910. In 1902
resource for Engler’s studies.
he journeyed to the Cape and
He carried out little field
Transvaal in South Africa, East
work but he was an accomAfrica and Egypt. In 1905 he
plished synthesiser of data
visited South and East Africa
from the notes and collecagain and also Zimbabwe,
tions of others. Botanists from
Zambia and the Zambezi
all over the world sent him
region, after which he went
material and information.
to India and Sri Lanka, where
Diels’s (1931) biography
he paid particular attention to
gives a detailed account of
economic plants and Araceae.
Engler’s life and work, from
His journey then took him to
which we have selected the
Bogor, Singapore, Malaysia,
main facts. Engler was born on
Burma, the Himalaya and
25th March 1844 in Sagan, Lower
Calcutta. In 1913 he went on a
Silesia (today Poland), the son of
world tour that took him to
a tradesman. In 1848 his mother
Southwest Africa, China, Japan,
took him to the provincial capital of
Hawaii, California and New
Breslau, where the young Engler
England. He was awarded honFigure 4. N.E. Brown (1849–1934).
grew up. From his early years he
orary doctorates of the Universities
Photograph c. 1900.
took a great interest in natural hisof Cambridge, Cape Town,
tory and during his University years
Uppsala and Geneva and the gold
studied with the famous palaeobmedal of the Linnean Society. He
otanist and teacher H.R. Goeppert, later becoming a
retired officially as Director at Berlin on 31st March
teacher himself for a short time in Breslau (today
1921 but continued his scientific work until his death
Wroclaw). In 1869 he became acquainted with A.W.
on 10th October 1930.
Eichler who had succeeded C. von Martius as editor of
K. Krause continued to work on Araceae at Berlin
the “Flora Brasiliensis” and this contact was to be of
until 1942, publishing new species collected by vargreat significance for his future career. In April 1871 he
ious field botanists and collectors, especially those
was employed as a scientific assistant at the Botanische
working in South America, but he did not take up his
Sammlungen (herbarium and living collections) in
studies again after the Second World War ended in
Munich. Here, under the guidance of Nägeli’s direc1945 and died in obscurity in 1963. A manuscript
torship, he matured scientifically for eight years until he
that he completed in 1942 for the second edition of
was 34 years old. The botanic garden and herbarium,
Die natürlichen Pflanzenfamilien was lost in 1943
together with the library (Bayerische Staatsbibliothek)
when the Berlin Botanical Museum was largely
provided excellent working conditions. He worked up
destroyed by war action.
his professorial qualification (habilitation) in 1872 and
Nicholas Edward Brown (1849–1934), working at
later taught at the University. Engler’s period at Munich
the Herbarium of the Royal Botanic Gardens, Kew,
was clearly the most creative of his life as far as the
made significant contributions to Araceae systematics.
Araceae were concerned, since it was there that he
His largest and most important publication on
made most of his important innovations and insights
Araceae was the family treatment for Flora of Tropical
into the family’s taxonomy.
Africa (Brown 1901), but in addition to this he pubIn 1879 Engler became a professor ordinarius at
lished various other flora treatments, many new
the University of Kiel, where he also became Director
species and various new genera. Many of his new
of the botanical garden and institute. However, after the
taxa were based on living material introduced into the
death of Goeppert in 1884 he was appointed to sucgardens at Kew. Brown’s work is particularly notable
ceed his former professor at the University of Breslau
for his meticulous descriptions based on accurate
which included the directorship of the botanic garden.
observation and it is evident that his grasp of Araceae
There he began work on Die natürlichen Pflansystematics was profound. Brown was an almost exact
zenfamilien together with K. Prantl. After five years, he
contemporary of Engler. He began work at the Kew
moved to Berlin in October 1889 to become the
Herbarium as an assistant in 1873 and retired in 1914
Director of Germany’s largest botanical garden and
as an Assistant Keeper.
4
THE GENERA OF ARACEAE
1-22 Section A Acro 18/7/97 8:01 Page 5
Joseph Dalton Hooker (1883), in Bentham &
Hooker’s Genera Plantarum, published a classification
of Araceae based largely on Schott’s (1860) work which
was later revised and modified by John Hutchinson
(1934, 1959, 1973), another Kew botanist. Hutchinson
made an impact on Araceae taxonomy because his
treatment included a key to all genera in English.
However, aroid specialists have found his system to be
artificial and it was never widely used.
T. Nakai (1943) published a new classification in
which he recognized the Pistiaceae, Cryptocorynaceae
and Acoraceae as separate families from the Araceae.
He also made important contributions to the systematics of the genus Arisaema.
After 1945 a period of relative inactivity followed,
until the 1950s when George S. Bunting, Monroe
Birdsey, Dan H. Nicolson and Josef Bogner began
working on the family. M. Hotta began to publish on
Araceae in the 1960s (Hotta 1965, 1966a–b, 1967) and
later he presented a classification for Eastern Asian
and Malesian genera and an influential study of vegetative and floral morphology (Hotta 1970, 1971).
Since then he has made many important investigations
of aroids in the Malay Archipelago region (Hotta 1976,
1981, 1982, 1984, 1985, 1986a–b). Other important
studies carried out during this period are those by G.
Thanikaimoni (pollen morphology, 1969) and C.
Marchant (1970, 1971a–b, 1972, 1973, cytology).
Floristic and revisionary studies in the 1950s and
1960s that should be mentioned are those of H.C.D.
de Wit (Cryptocoryne, Lagenandra), H. Riedl (Flora
Iranica, Eminium), Bunting (Spathiphyllum) and
Nicolson (Aglaonema).
In the 1970s and 1980s, the pace of work on the
systematics of Araceae increased. In 1978 the
International Aroid Society was formed in Florida, USA
and the journal Aroideana founded, originally under
the energetic editorship of M.T. Madison. Aroideana
generated a significant expansion of scientific and
horticultural interest in the family and continues to
play an important role. A series of international workshops on Araceae systematics was established,
beginning at Sarasota (1980), and continuing at
Harvard Forest (1984), Berlin (1987), Moscow (1992),
Tokyo (1993), and Kunming (1995), with further meetings planned for Sydney (1998) and St Louis (1999).
These events have done a great deal to foster international collaboration.
Bogner (1979a) updated the Engler classification,
adding newly described genera and taking account of
new synonymy. Nicolson (1983) published an English
translation of Engler’s classification, including the
accepted genera described since 1920. Bogner &
Nicolson (1991) published a revised synoptic key to all
the genera, which incorporates a number of important changes from Engler’s concepts, particularly in the
subfamilies Pothoideae and Lasioideae. M.H. Grayum
(1984, 1990) presented a new phylogenetic classification which is especially notable for recommending the
removal of Acorus from Araceae and the large scale
reorganization of Engler’s subfamilies.
Grayum’s work, in particular, has been a stimulus
to other workers to initiate new studies of taxonomically significant character fields, largely due to his
comprehensive review of the technical literature.
Recent comparative character surveys of particular significance are the studies of J.C. French (anatomy, also
with P.B. Tomlinson), T. Ray and P. Blanc (shoot morphology), G. Petersen (cytology), M. Grayum
(palynology), H.-J. Tillich (seedling morphology), D.
Barabé, L. Chrétien, S. Forget and M. Labrecque (floral anatomy), W.N. Carvell (floral anatomy), E. Seubert
(seed anatomy) and J.C. French, M. Chung & Y. Hur
(cpDNA molecules).
There are many centres of research on Araceae
systematics now active throughout the world, including those in Brazil (I.M. Andrade, C. Barros, E.
Gonçalves, A. Lins, M. Nadruz Coelho, M.L. Soares, F.
Ramalho, C. Sakuragui, J. Waechter). Calicut (M.
Sivadasan), Copenhagen (N. Jacobsen, G. Petersen),
Kew (S.J. Mayo, P.C. Boyce, G. Kite), Kunming (Li
Heng), Kyoto and Kagoshima (M. Hotta), Leiden (W.
Hetterscheid), Moscow (M. Serebryanyi), Munich (J.
Bogner), Rutgers University, New Jersey (J.C. French,
M. Chung, Y. Hur), St. Louis (T.B. Croat, M.H. Grayum,
G. Zhu), Sydney (A. Hay), Tokyo (J. Murata),
Washington DC. (D.H. Nicolson), and until recently, at
Yaoundé (C. Ntépé-Nyame†).
With this increase in taxonomic activity, new revisions and floristic studies are now in progress which
should eventually lead to a much more complete
knowledge of the family.
H I S TO RY
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1-22 Section A Acro 18/7/97 8:01 Page 6
2
C
V E G E TAT I V E M O R P H O L O G Y
Root
Roots in Araceae are always adventitious and dimorphic
roots are often found in climbing hemiepiphytes, e.g.
Monstera deliciosa, Philodendron bipinnatifidum. In
some genera, e.g. Arisarum, Arum, Biarum,
Cryptocoryne, specialized contractile roots occur which
prevent the stem from rising too near to the soil surface;
more details of root structure are given in Chapter 3.
Stem
Pinellia, and hypogeal stolons in Colocasia,
Cryptocoryne, some Spathiphyllum spp. and
Lasimorpha.
Shoot organization shows a range of interesting variation within the family and can be taxonomically useful
(Engler 1877, Blanc 1977a,b, 1978, 1980, Ray 1986,
1987a–c, 1988, 1990). In virtually all genera the mature
stem is a sympodium composed of sympodial units (articles) each of which has a more-or-less determinate
structure, beginning with a prophyll and ending with an
inflorescence or aborted inflorescence. Foliage leaves
and cataphylls (reduced sheath-like leaves) occur in a
sometimes very regular sequence within each unit.
Continued growth of the stem takes place in most genera by the development of a “continuation shoot” in the
axil of the leaf (foliage leaf or cataphyll) situated at the
second node below the spathe insertion. In the subfamily Orontioideae it arises at the first node below the
spathe. The production of more than one inflorescence
to form a floral sympodium commonly takes place by the
development of short units consisting of a prophyll, a
spathe and a spadix. The first unit arises in the axil of the
The stem varies from an aerial elongated axis with
extended internodes, as in the many climbing hemiepiphytes, to a hypogeal rhizome or subglobose tuber.
Climbing genera with long internodes are commonest
in the more primitive tribes, i.e. those with bisexual
flowers. Geophytes are found throughout the family
but are especially common in the most advanced subfamily, the Aroideae. Abbreviated aerial stems, resulting
in rosulate plant forms, are also commonly found, as
in many epiphytic species of
Philodendron and Anthurium. Some,
generally larger, species have an
Continuation shoot
arborescent habit, in which the main
Spathe
axis is a fleshy (Alocasia, Xanthosoma)
or fibrous (Philodendron) stem, or a
Spadix
pseudostem of petiole sheaths
Prophyll
(Arisaema, Typhonodorum). Shoot
Peduncle
types apparently specialized for vegeSympodial leaf
tative reproduction occur in various
forms. Flagelliform shoots, or “flagellae”, equivalent to aerial stolons, have
been observed in Amydrium, Cercestis,
Pedicellarum, Philodendron, Pothos,
Rhaphidophora, Rhodospatha, and
Syngonium among others. They consist
of branches (usually in the form of continuation shoots) in which the
internodes become very much longer
and more slender than in the flowering
zone of the stem, and the leaves often
Monopodial leaf
become reduced in size, sometimes to
small, scale-like cataphylls. Flagelliform
shoots grow rapidly, and thus
encounter new host trees on which
flowering stems later develop. Bulbils,
which appear to be dispersed by birds,
occur in Remusatia, while tubercles
occur in Amorphophallus bulbifer,
Dracontioides, Dracontium, and
Figure 5. Schematic diagram of a common form of shoot architecture in Araceae.
6
THE GENERA OF ARACEAE
1-22 Section A Acro 18/7/97 8:01 Page 7
leaf immediately below the spathe and succeeding ones
in the axils of the prophylls. These floral sympodia have
a range of structural variation which may be quite complex; extreme forms are found in Homalomena (Ray
1988). Anomalous shoot organization of an apparently
unique type occurs in Gymnostachys, while in most tribe
Potheae and Heteropsis the flowering axes occur as lateral short shoots on monopodial main vegetative axes of
apparently indeterminate growth.
Leaf
In virtually all genera the leaf is clearly differentiated into
an expanded blade, petiole and petiole sheath; exceptions are Gymnostachys and some Biarum species. The
sheath normally clasps the subtended internode, at least
basally, and has an annular insertion (except many
Potheae and most Heteropsis). The foliage leaves that
occur nearest the end of sympodial shoot articles (sympodial leaves) often have short or very reduced sheaths,
particularly when the article apex aborts and fails to
develop an inflorescence, e.g. in Philodendron.
The terminology adopted here to describe leaf shape
requires some explanation as it differs from traditional
practice. For descriptive purposes, the leaf is divided into
the anterior division, corresponding to that part of the
blade surrounding the midrib, and two posterior divisions, which, when present, are those portions of the
leaf blade which extend basally on each side of the
petiole insertion. In many genera, e.g. those comprising
the Monsteroideae, there are no posterior divisions and
the blade is composed entirely of the anterior division.
In other taxa, such as the Lasioideae, many species have
deeply sagittate leaves with very strongly developed
posterior divisions, sometimes exceeding the anterior
division in length. In strongly sagittate leaves, each posterior division usually has a well developed basal rib,
which performs the same mechanical support role as the
midrib does for the anterior division. In cordate and
cordate-sagittate leaves the basal ribs may be short or
even absent, with the individual primary lateral veins
arising independently at the base of the midrib. On the
other hand, pedately divided leaves, as seen for example in Philodendron goeldii or Sauromatum venosum,
have a central, undivided anterior division while the
posterior divisions are represented by the lateral series
of pedate segments on either side. Here the basal ribs
are represented by the “arms” on which the segments of
the posterior divisions are inserted and which arch back
from the midrib insertion at the apex of the petiole.
Leaf blade size and shape is exceedingly diverse.
Size may range from diminutive (e.g. Ambrosina) to
gigantic (e.g. Alocasia, Amorphophallus, Anchomanes,
Cyrtosperma, Xanthosoma ). Shape varies from linear
(Biarum, Jasarum) to dracontioid (tribe Thomsonieae,
Anchomanes,
Dracontium, Pseudohydrosme,
Pycnospatha, ), through elliptic, ovate, cordate, sagittate,
hastate, trifid or trisect, pedatifid, pinnatifid, pedatisect,
pinnatisect and radiatisect. Sometimes the posterior divisions of pedatifid and pedatisect leaves are twisted
spirally so that the leaf segments resemble a spiral staircase (Eminium, Helicodiceros). Bipinnatifid, tripinnatifid
and partially quadripinnatifid leaves also occur.
Dracontioid leaves may be viewed as elaborated forms
of sagittate, hastate, trisect or pedatisect leaves in which
the anterior and posterior divisions of the leaf blade
have become highly dissected during ontogeny by differential growth of the margin, necrosis of parts of the
blade, or a combination of both processes. The mature
leaf can be compared to an umbrella which has been
blown inside out by a gale — the spokes correspond to
a much-divided system of major leaf ribs and the canopy
is rent into numerous “tattered” lamina lobes which
adhere to the ribs and are more regularly shaped at the
tips of the major leaf veins. Gonatopus has a somewhat
similar leaf form while Zamioculcas and certain species
of Anaphyllum and Anaphyllopsis have completely pinnatisect leaves. The first foliage leaf of a seedling is
always entire (sagittate–hastate) in the genera
Anaphyllopsis, Anaphyllum, Anchomanes, Dracontium,
and Pycnospatha, but divided (dracontioid type) in the
genera Gonatopus and Amorphophallus.
Heteroblasty is a striking and sometimes taxonomically useful feature (e.g. Madison 1977a) of a number of
climbing genera (Cercestis, Monstera, Philodendron,
Pothos, Rhaphidophora, Rhodospatha, Syngonium). It
occurs both in ontogeny from seedling to the mature
plant and in association with the development of flagelliform shoots. A very striking form of heteroblasty is
shown in certain genera (e.g. Monstera, Pothos) where
the juvenile leaves have very short petioles and their
blades are held flat against the host tree in a regular, overlapping sequence giving the appearance of roof shingles
or tiles; these are consequently known as shingle plants.
Monstera dubia is a well known example which also has
beautifully variegated leaf blades in this growth phase.
Perforated (fenestrate) leaves are another peculiarity of Araceae in genera such as Dracontioides,
Monstera, Rhaphidophora, and in juvenile leaves of
Anchomanes and certain species of Cercestis. A number of genera have species with peltate leaves (tribe
Colocasieae, Anthurium, Caladium, Homalomena).
The midrib is almost always present, being absent
only in Gymnostachys and Pistia. The major veins
which compose the midrib and basal ribs and branch
laterally from them are termed primary lateral veins.
Secondary, tertiary and higher orders of lateral veins are
recognized by their relative thickness and/or their hierarchical level of branching. The primary lateral veins
may be arcuate-parallel (e.g. Ambrosina), pedate (e.g.
Sauromatum) or radiate (e.g. many Arisaema spp.) but
most commonly are pinnately arranged. Even in pedatifid (-sect) and radiatisect leaves, the primary lateral
veins of each segment are generally pinnate.
Except in deeply divided leaves, the primary lateral veins always run throughout the leaf blade,
ultimately joining together at the leaf apex (Ertl 1932).
VEGETATIVE MORPHOLOGY
7
1-22 Section A Acro 18/7/97 9:26 Page 8
The primary lateral veins generally run to the margin
first, where they form a marginal vein which then
runs to the leaf apex. In some species, most primary
lateral veins curve arcuately within the margin to fuse
together at the apex, and in these cases only the lowermost primaries run into the margin to form a
marginal vein. In other genera either one or several
of the primary lateral veins form a submarginal collective vein (brochidodromous pattern) which lies
parallel to the marginal veins.
The finer venation may be reticulated (e.g.
Anthurium) or may run essentially parallel to the pinnately arranged primary lateral veins (e.g.
Philodendron). This is often referred to as “parallel” or
“striate” venation in aroid literature. In this book we
refer to the latter type as parallel-pinnate, to distin-
guish it from true, grass-type parallel venation, which
in Araceae occurs only in Gymnostachys. A third type
of fine venation (“colocasioid venation”) has been recognized by previous authors for tribes Colocasieae and
Caladieae. In this pattern the finer veins branch almost
at right angles from the primary lateral veins and then
arch strongly towards the leaf margin, often fusing on
the way to form a more-or-less sinuose interprimary
collective vein and then finally joining into a submarginal collective vein. Intermediates occur between most
recognized types. Venation patterns and their development require new investigation, particularly because
of their great potential for facilitating identification of
species and genera. Ertl’s study (1932) is the only large
scale comparative survey yet made of this important
character field.
ANTERIOR DIVISION
Midrib
Primary lateral vein
Petiole insertion
Submarginal collective vein
POSTERIOR DIVISION
POSTERIOR
DIVISION
ANTERIOR
DIVISION
B
Basal ribs
Petiole
ANTERIOR
DIVISION
POSTERIOR
DIVISION
A
Petiole
POSTERIOR DIVISION
Basal ribs
Petiole
C
Figure 6. Leaf division types: A, no posterior division development; B, moderate posterior division development; C, extreme posterior
division development.
8
THE GENERA OF ARACEAE
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C
3
V E G E TAT I V E A N ATO M Y
By James C. French
The vegetative anatomy of the Araceae is among the
most diverse of any family of monocotyledons. Stem
vasculature is the most diverse of any monocotyledon
group and virtually every known type of secretory structure occurs, including resin canals, laticifers, extrafloral
nectaries, mucilage cavities and intravaginal squamules.
Root
The first root to emerge from the seed is a short-lived
extension of the radicle. Subsequent roots arise from
the stem and may form lateral roots. The stem is the
normal site of root origin in Araceae, a pattern referred
to by Troll (1949) as “secondary homorhizy” and typical of monocotyledons.
Anchor and feeder roots
Aerial roots of epiphytic and climbing Araceae are
often specialized into anchor roots (Haftwurzeln) that
serve to attach the plant to the substrate which provides support, and feeder roots (Nährwurzeln) which
extend to the soil and supply water and dissolved
nutrients (Went 1895).
A number of anatomical, morphological and physiological differences between anchor and feeder roots have
been described (Schimper 1888, Lierau 1888, Wettstein
1904, Gaulhofer 1907, Linsbauer 1907, Porsch 1911,
Solereder & Meyer 1928, Funke 1929, Goebel & Sandt
1930, Birdsey 1955, Guttenberg 1968, Madison 1977a).
Both anchor and feeder roots typically arise close to the
node, although the former may arise along the internode
as well in some species of e.g. Anthurium, Epipremnum,
Monstera, Rhaphidophora and Scindapsus (Madison
1977a, Croat & Baker 1978, Hotta 1971). According to
Troll (1941), the association between anchor and feeder
roots can be highly specific, as in the monophyllous
sympodium of Philodendron. In P. scandens a feeder
root develops near the insertion of the foliage leaf, while
anchor roots develop nearby at the insertion of the subadjacent prophyll. In Araceae with root dimorphism
anchor roots are more numerous than feeder roots at the
same node.
The morphology and physiology of anchor and
feeder roots are markedly different. The former are typically relatively narrow, agravitropic and appear to be
negatively phototropic, which tends to bring them into
contact with the substrate. Numerous root hairs are typically produced on the side adjacent to the substrate, but
may develop all over the root (Troll 1941). Anchor root
growth is relatively limited and often dependent upon
contact with a substrate. With no contact, growth ceases
precociously, whereas prolonged contact stimulates
elongation. Anchor roots never attain the enormous
lengths of feeder roots. In Monstera (Madison 1977a)
the stems not in contact with a substrate produce only
a tuft of dried anchor roots, while those in contact produce anchor roots 20–30cm in length. The latter may
surround tree trunks, for example. Root hairs serve to
attach the root to a substrate, often forming a pseudoparenchymatous layer (Went 1895). Some anchor roots
may lack root hairs and appear to be cemented by
dried mucilage, as in Syngonium.
Feeder roots are thicker than the associated anchor
roots and are capable of considerable elongation. In
some species of Monstera they may extend 30m to the
forest floor (Madison 1977a). Feeder roots are considered positively gravitropic, although their tips do not
hang vertically in some cases (Linsbauer 1907). Feeder
roots may hang freely in the air for their entire length
or they may adhere to a tree trunk, e.g. Syngonium
(Troll 1941) even though no root hairs are produced.
Mucilage may play a role in their adhesion as it is often
more abundant than on anchor roots (Went 1895).
Feeder roots do not generally branch before reaching
the soil unless injured. However, Philodendron
melanochrysum and some Syngonium species normally produce aerially branched feeder roots (Troll
1941). The lateral roots of decapitated feeder roots also
lack root hairs and show positive gravitropism. Once
the typically unbranched feeder roots of most species
enter the soil they branch profusely.
In Monstera (Madison 1977a), dimorphic roots do
not appear until plants have reached about a metre
above the ground and the stem is 7–10 mm thick. After
a prolonged period without contact, as in a pendent
shoot, only tufts of non-growing anchor roots are produced. Hinchee (1981) studied root development in
Monstera before and after entry into the soil. Unfortunately Hinchee used the term Haftwurzeln erroneously,
applying it to feeder roots prior to their entry into the
soil, and reserved the term Nährwurzeln for their subterranean branches. This misapplication of terminology
invalidates comparisons that are made with previous
studies of true anchor and feeder roots (Guttenberg
1968) since Hinchee did not study Haftwurzeln.
Some climbing Araceae, such as Scindapsus
pothoides (= S. hederaceus) do not show a clear distinction between anchor and feeder roots (Went 1895).
In these instances anchor roots develop all over the
stem, but are larger and longer at the nodes and may
reach to the soil. Internodal roots are also found in
V E G E TAT I V E A N ATO M Y
9
1-22 Section A Acro 18/7/97 8:01 Page 10
Anthurium sect. Polyphyllium (Croat & Baker 1978), as
in A. clidemioides. Some feeder roots of Araceae are
capable of contraction (Wettstein 1904, Rimbach 1922).
Anchor roots, on the contrary, do not appear to contract. Rimbach found that contraction was absent in
feeder roots of Monstera deliciosa but present in
Philodendron bipinnatifidum where he observed that
a feeder root contracted by about 20% over 5 months.
Root growth
The average length of the elongation zone of
Philodendron species has been observed as 20–50
mm, with the maximum found in P. selloum (= P.
bipinnatifidum), amounting to over 90 mm. Hinchee
(1981) reported that the elongation zone in Monstera
aerial (probably feeder) roots may be as long as 105
mm. Actual rates of growth for Philodendron aerial
roots were less than 10 mm/day for most species. The
large roots of P. selloum (= P. bipinnatifidum) grew
exceptionally fast, from 7–21.5 mm/day. Daily growth
rates in Monstera deliciosa ranged from 3–40 mm/day
for aerial roots. According to Hinchee (1981) aerial
roots of Monstera exhibit an exponential increase in
growth rate during aerial growth. Once roots enter
the soil their rate of growth declines and maintains
a relatively constant value.
Adventitious roots
Adventitious roots arise from the inner stem cortex at
some distance from the shoot apex, and they often
have a broad attachment to the vascular cylinder of the
stem, e.g. in some Pothoideae and Monsteroideae
(French & Tomlinson 1981a, b). The adventitious roots
of Pothos, Pothoidium and Heteropsis have a close spatial relationship to leaf traces. In Pothos and Pothoidium
each lateral leaf trace diverges from the central cylinder to the leaf through the region of the root trace
attachment. In Heteropsis only the mid-vein leaf trace
diverges through the region of root attachment (French
& Tomlinson 1981a).
The origin of lateral roots in Araceae is typical of
many monocotyledons and has been studied in
Anthurium, Colocasia, Monstera and Zantedeschia.
Pistia is atypical in several respects. Firstly, lateral roots
arise very close (110–350 µm) to the root cap and apex
junction (Charlton 1983). The lateral root primordia of
Pistia tend to arise regularly along the length of the
xylem strands in the central cylinder, but no evidence
was found for regular spacing between the rows of
root primordia (Charlton 1983). Secondly the roots of
Pistia are unusual in the Araceae in their development
of a persistent pocket or “Tasche”, which is a kind of
“substitute” root cap. This structure also occurs in some
other aquatic monocotyledons, e.g. Lemna, Spirodela,
Eichhornia (Guttenberg 1968).
10
THE GENERA OF ARACEAE
Nest roots
Another type of aerial root has been described in
Anthurium ellipticum and is characteristic of many
other species of Anthurium sect. Pachyneurium, the
“bird’s nest” or “litter basket” anthuriums. This is the socalled nest root (Schimper 1888, Bruhn 1910). These
exhibit negative gravitropism (Troll 1941) and branch
profusely forming an “impenetrable” nest. The development of these roots was studied by Bruhn (1910)
who found that their formation was typically inhibited
when the roots were surrounded by moist moss or
earth. Bruhn concluded that they resulted from damage to the root apex. However, more recent field
studies suggest that nest roots are mainly for feeding.
In these epiphytes the rosulate leaves form a “basket”
into which leaves, twigs and other detritus gather. The
nest roots seem to be especially adapted to exploit
this food resource, growing directly up into the mass
of detritus and ramifying within it (Croat 1991).
Contractile roots
These roots occur in numerous Araceae which possess
a tuberous habit, for example Typhonium (Banerji
1947), Arum (Rimbach 1897), other genera of subfamily Aroideae (Rimbach 1898), subfamily Orontioideae
(Lysichiton, Orontium, Symplocarpus), some genera
of subfamily Lasioideae (Hotta 1971), and some other
aquatic species, as in Cryptocoryne, but not Calla
(Dudley 1937).
Detailed studies of root contraction have been made
in two species of Arum. Rimbach (1897) followed the
life history of Arum maculatum in the field, presumably in Germany, from seed germination to adult plant
and studied in particular the phenology of shoot and
root growth. Lamant & Heller (1967) studied the mechanism of contraction in Arum italicum. They observed
that contraction was related to: 1) radial expansion of
cortical parenchyma, which results in longitudinal tension, and 2) release of such tension by the collapse of
proximal outer cortical tissues and shortening of the
stele. Similar mechanisms occur in other contractile
roots and were discussed in more detail by Ruzin
(1979) and Jernstedt (1984). Galil (1978) found active
lateral contractile roots in shallow, horizontally attenuated rhizomes of Arisarum, which pull the rhizome
laterally rather than downwards. A second type of rhizome, which grows vertically at deeper levels, lacks
contractile roots and is non-mobile.
Root epidermis
The epidermis of most aroid roots is composed of a
single layer of cells which nearly always includes both
ground cells and root hairs. More than one epidermal
layer has been reported for a number of genera,
1-22 Section A Acro 18/7/97 8:01 Page 11
including Aglaonema, Anthurium, Gonatopus and
Homalomena (Lierau 1888, Solereder & Meyer 1928),
but these results were largely based on studies of
mature roots only, which do not provide conclusive
evidence. Root hairs were reported to be absent from
subfamily Calloideae (sensu Krause 1908) but the
entire family is clearly not “without root hairs” as
described by Cronquist (1981). In fact two types of
root hair development have been described (Leavitt
1904). In Type I, any protodermal cell may form a
root hair, as in Aglaonema, Arisaema, Caladium,
Dieffenbachia and Zantedeschia. In Type II, root hairs
arise only from specialized trichoblasts, as in
Anthurium and Monstera. Root hairs are usually not
formed on feeder roots of hemiepiphytes until they
penetrate the soil (Solereder & Meyer 1928, Lierau
1888, Guttenberg 1968, Hinchee 1981). However,
anchor roots form abundant root hairs, in some cases
from every cell (Guttenberg 1968). In many species the
root hair tips of anchor roots are modified by branching or are flattened and become cemented to the
substrate and to each other, possibly by exudates from
the root (Richter 1901, Lierau 1888, Madison 1977a).
Mucilage has frequently been observed on roots of
climbing Araceae (Went 1895, Guttenberg 1968).
Unusual scales have been described on the roots of
Pothos and Monstera resulting in a striped appearance
(Richter 1901).
One of the most distinctive anatomical features of
the roots of some Anthurium species is the presence
of a true multiple epidermis which resembles the
velamen of Orchidaceae and some other monocotyledons (Guttenberg 1968) in having a thick
water-absorbing layer that is white when dry. Limited
developmental studies have shown that the protoderm of these species exhibits tangential cell divisions
resulting in multiple layers of epidermis (Guttenberg
1968). In some Anthurium species the velamen has
long been recognized (Leitgeb 1865, Tieghem 1867,
Lierau 1888, Schimper 1888). The multiple epidermis
of Anthurium gracile exhibits a white velamen when
dry (Croat 1984). Engler (1920b) noted that the multiple epidermis of some Anthurium species,
particularly in section Pachyneurium, contains dead
cells with fibrous thickenings and granular structures
on the innermost tangential wall layer. Densely cytoplasmic “passage cells” have also been observed,
which are similar to cells found in some Orchidaceae
(Deshpande 1956). Fibrous thickenings have been
observed in A. affine, A. crassinervium, A. maximum,
A. willdenowii, among others, according to Lierau
(1888), Leitgeb (1865), Schimper (1888) and Solereder
& Meyer (1928). Some Anthurium species exhibit a
smooth-walled multiple epidermis (A. huegelii (= A.
hookeri), A. cucullatum (= A. andicola); Schimper
1888, Leitgeb 1865).
Root cortex
In the roots of many Araceae an exodermis is present
beneath the epidermis, which becomes the outer protective layer if the latter is lost (French 1987b). The
exodermis or “Interkutis” is suberized and the outer walls
may become thickened as in some Anthurium species.
Patterns of cell shape are variable, with some roots having exclusively elongated exodermal cells, as in Calla.
Other roots have alternating long and short cells, as in
Monstera deliciosa (Sinnott & Bloch 1946, Hinchee 1981)
or Anthurium (Leitgeb 1865). Although an exodermis is
present in most Araceae examined so far (Olivier 1881,
Schimper 1888, Solereder & Meyer 1928, Hinchee 1981,
French 1987b), it is by no means universal. An exodermis is reportedly absent from Pistia (Guttenberg 1968).
Beneath the exodermis a specialized multilayered
sclerotic hypodermis develops in the roots of seven
genera: Anubias, Cercestis, Culcasia, Furtadoa,
Homalomena, Montrichardia and Philodendron
(Lierau 1888, Solereder & Meyer 1928, French 1987a).
The organization of the ground tissue of the cortex of
Araceae varies considerably among different genera. In
species with aerial roots the outer cortex contains
chloroplasts. Collenchyma has also been reported in
this region in feeder roots of both Monstera (Hinchee
1981) and Philodendron (Porsch 1911) as well as other
root climbers. The ground tissue of the cortex is usually composed of relatively thin-walled, unlignified
parenchyma cells. In many aquatic or semi-aquatic
genera and some others, large schizogenous intercellular spaces, or lacunae, are present. These occur in
Amorphophallus, Anchomanes, Calla, Colocasia,
Dracunculus, Philodendron and Syngonium (Lierau
1888). The feeder roots of Syngonium develop large
intercellular spaces, while the anchor roots do not
(Went 1895). Trichosclereids have been reported in
intercellular spaces only in Monstera deliciosa,
Rhaphidophora decursiva and Scindapsus pteropodus
(=Rhaphidophora pteropoda) (Lierau 1888, Solereder &
Meyer 1928) despite their common occurrence in other
organs. Thick-walled cells, some with pits, are mentioned by several authors (Lierau 1888) as occurring in
the cortex of some Monsteroideae, but have not been
described in detail.
A variety of secretory tissues occurs in the cortex.
Resin canals are present in the cortex of Philodendron,
Homalomena and Furtadoa (Trécul 1865, 1866, Lierau
1888, Porsch 1911, Engler 1912) and in Culcasia and
Cercestis (French 1987b). More details of organization
are given in the section on resin canals. Laticifers also
occur in the root cortex of a limited number of species,
including Syngonium (Weiss 1866). Numerous crystalcontaining and tanniniferous idioblasts also occur in the
root cortex (Solereder & Meyer 1928).
The inner cortex typically contains narrower cells
arranged in concentric rings adjacent to relatively smaller
intercellular spaces in Amorphophallus, Colocasia,
Dieffenbachia, Homalomena, Philodendron, Scindapsus,
V E G E TAT I V E A N ATO M Y
11
1-22 Section A Acro 18/7/97 8:01 Page 12
Syngonium and other genera (Solereder & Meyer 1928).
The inner cortical region of many Monsteroideae and
some Pothoideae contains a sheath of brachysclereids,
fibres or sclerotic parenchyma, one to several layers
thick (Tieghem 1867, Lierau 1888, Went 1895, Solereder
& Meyer 1928, Sinnott & Bloch 1946, Hinchee 1981).
This sheath may be in direct contact with the endodermis as in Spathiphyllum kochii (Lierau 1888) or separated
from it by one or more cell layers. The latter condition
occurs in Epipremnum pinnatum (Tieghem 1867), several species of Rhaphidophora (Solereder & Meyer
1928), Pothos celatocaulis (= R. korthalsii) (Lierau 1888)
and P. scandens (Went 1985).
An endodermis with a Casparian strip is probably
present in roots of all Araceae (Solereder & Meyer
1928). Particularly in older aerial roots, the walls of
the endodermis become thickened and suberized, thus
obscuring the Casparian strips. In most species suberization begins first in the endodermis adjacent to the
phloem and only later progresses to the region adjacent
to the xylem. This pattern is typical of monocotyledons.
Vascular cylinder of roots
The vascular cylinder of roots of Araceae is typically
cylindrical and exhibits an alternating, radial arrangement of xylem and phloem. However, lobing of the
cylinder occurs in some species of Philodendron and
in Cercestis. Some species of Epipremnum and
Philodendron have converging V-shaped xylem
strands with narrower phloem strands in their angles
and between them. Anomalous organization of vascular tissues occurs in some Monstereae (Monstera,
Rhaphidophora, Scindapsus), Anthurium and
Philodendron. In these genera the vascular region of
the central cylinder consists of interspersed strands of
phloem and xylem. The latter are generally one vessel in width while the phloem strands comprise several
wide sieve elements (Hinchee 1981). Ground tissue of
the central cylinder often becomes sclerotic in older
roots. A pericycle has been reported (Hinchee 1981)
and a pith region may be present or absent. Meyer
(1925) followed the course of the inner vascular tissue
in roots of Anthurium and Monstera and found that
phloem and xylem strands remained separate in
Anthurium wagenerianum. In Monstera deliciosa
connections were observed between vascular strands,
both in the periphery and the centre of the root.
Root apex
Relatively few studies of apical organization have been
made in Araceae. Guttenberg (1968) described an open
pattern of apical organization. Hinchee (1981) demonstrated the presence of a quiescent centre in both the
feeder root and its subterranean branches.
More attention has been given to the structure of
12
THE GENERA OF ARACEAE
the root caps of dimorphic aerial roots. Earlier workers (Haberlandt 1914) reported the presence of normal
“statolith” starch grains in the columellas of gravitropic
feeder roots of Monstera deliciosa (and other species),
which has been confirmed by Hinchee (1981). In
agravitropic clasping roots it is generally agreed that the
size of the columella is smaller than in feeder roots and
fewer “statocytes” are present (Haberlandt 1914).
Several reports contend that columella starch grains
are “sluggish or motionless” in clasping roots
(Gaulhofer 1907, Haberlandt 1914), however Linsbauer
(1907) found mobile grains.
Development of the mature cortex was studied in
Monstera deliciosa by Bloch (1946), Sinnott & Bloch
(1946) and Hinchee (1981). The exodermis has alternating short and long cells resulting from unequal
divisions that occur 2.5–3.5mm from the apex. Beneath
the exodermis certain cells in longitudinal files undergo
unequal divisions resulting in a smaller basal cell which
then develops into a trichosclereid (Bloch 1946). The trichosclereid initials develop adjacent to intercellular
spaces into which the cell arms elongate intrusively.
Bloch (1946) found trichosclereid initials only at the
distal ends of files, but Hinchee (1981) reports finding
small, densely cytoplasmic, putative trichosclereid initials elsewhere. Asymmetric cell divisions were also
associated with the formation of raphide cells by Kovacs
& Rakovan (1975), but were not observed by Hinchee
(1981). Sinnott & Bloch (1946) emphasized the role of
unequal cell division, internal environment and cell
position in the differentiation of cells of the exodermis
and trichosclereids. In contrast, the development of the
inner layer of brachysclereids adjacent to the endodermis is not dependent on unequal cell division. Similar
short sclereids develop at the surface in response to
wounding of the root, by redifferentiation of their
walled cortical cells, which Sinnott & Bloch (1946) interpreted as an effect of a changed environment.
Periderm formation
A cork cambium is generally formed in the cell layer
below the exodermis in aerial roots of Monstera (Richter
1901, Hinchee 1981), Anthurium and Rhaphidophora
(Olivier 1881), and replaces the exodermis as the outermost protective layer. In Monstera deliciosa the
periderm begins to develop about 60 mm from the root
apex in feeder roots and 10–15 mm from the apex of
subterranean lateral roots (Hinchee 1981). Following
cork formation, epidermal cells collapse in Monstera
and Philodendron (Engler 1912). Cork may consist of
alternating layers of thin-walled and sclerenchyma cells
in Monstera (Hinchee 1981). In Philodendron the phellogen arises under layers of the sclerotic hypodermis and
forms a wide layer of periderm in some species (Engler
1912). Lenticels also occur in the roots of Anthurium
and other species (Weisse 1897). The lenticels of
Monstera contain filling tissue as well as closing layers.
1-22 Section A Acro 18/7/97 8:01 Page 13
Stem
Stem anatomy and morphology are frequently correlated in Araceae, particularly with respect to the
overall organization of the vascular system (Engler
1920b, French & Tomlinson 1981a–d, 1983, 1984).
Conducting tissue tends to be highly condensed in
tuberous species and in rhizomes with short internodes, compared with scandent plants. Climbing
genera are largely concentrated in subfamilies
Pothoideae and Monster oideae, but climbing
hemiepiphytes occur in subfamily Aroideae as well,
including Cercestis and Culcasia (tribe Culcasieae),
Philodendron (tribe Philodendreae) and Syngonium
(tribe Caladieae).
Grayum (1984) pointed out that it is sometimes difficult to distinguish between rhizomes and tubers in the
Araceae. Tubers are common in subfamily Aroideae
(tribes Areae, Arisaemateae, Arisareae, Arophyteae,
Caladieae, Colocasieae, Nephthytideae, Spathicarpeae,
Thomsonieae, Zamioculcadeae, Zantedeschieae,
Zomicarpeae). Hotta (1971) drew a distinction between
two types of tuber in Araceae, the Amorphophallus
type which is also found in Zamioculcas and
Gonatopus, and the Arisaema type, which also occurs
in Remusatia. The principal difference between them
lies in the way new tubers form and the ease with
which they are separated. In Amorphophallus, successive tubers develop from each other without
separating, while in Arisaema new tubers are separated from the older tissue by cork layers.
Stem epidermis
The stem epidermis exhibits many of the same features as that of the leaf with regard to occurrence of
trichomes, which are discussed in the section on
leaves. Older stems of many Araceae develop a periderm in the outer cortex or epidermis which
ultimately leads to the death of the epidermis (French
& Tomlinson 1981a–d, 1983).
Stem cortex
The cortex is delimited from the central cylinder by
its less dense clustering of vascular bundles, and
sometimes by the presence of an endodermis. The
principal sources of histological variation in the cortex are: 1) width, 2) vascular organization, and 3)
various specializations of the ground tissue. In many
Monsteroideae, some Pothoideae and other genera
like Culcasia, Cercestis and Philodendron, an especially distinct inner cortical boundary is present
because the sclerotic sheaths of the peripheral vascular bundles of the central cylinder are fused
together. In many Monsteroideae the inner layers of
the cortex also become sclerotic. Some species, like
Calla palustris, have no endodermis and widely separated central cylinder bundles. Root traces are
typically inserted along the periphery of the central
cylinder and serve as useful markers.
The vascular bundles in the cortex generally
belong to two different systems: 1) leaf traces that
traverse the cortex but may remain there for a longitudinally short distance, never exceeding one
complete internode, and 2) cortical vascular bundles
that constitute a separate system, persisting in the
cortex over many internodes.
In all species in which leaf traces are followed
basipetally (using cinematographic techniques), they
appear to enter the cortex from the leaf at the node
and traverse it before entering the central cylinder,
where they ultimately attach to axial bundles. There
is considerable variation in the relative distance over
which leaf traces remain in the internode before
entering the central cylinder. In most species the
major leaf traces enter the central cylinder close to
the point of leaf insertion after traversing the cortex
at an acute angle, as in Anthurium polyschistum
(French & Tomlinson 1981a). The minor leaf traces
may remain in the inter-node for a variable distance,
in some cases extending to the base of the subjacent
internode. Fibre bundles enter the cortex from the
leaf in Homalomena and Pothos (and Acoraceae)
and end blindly in the inner cortex (Tieghem 1867,
Falkenberg 1876, French & Tomlinson 1981a,d) in a
manner similar to palms and some other monocotyledons (Zimmermann & Tomlinson 1967,
Zimmerman, Tomlinson & LeClaire 1974).
A separate cortical vascular system is present in a
few genera and tribes, including Anthurium, Caladium,
Chlorospatha, Dieffenbachia, Heteropsis, Monstereae,
Pothoidium, Pothos, Philodendron, Syngonium and
Xanthosoma (French & Tomlinson 1980, 1981a–d, 1983,
1984, Grayum 1984). In addition to the persistent cortical bundles there may also be a series of minor and
intermediate leaf traces. It is not uncommon for minor
leaf traces to fuse with the cortical system and remain
separate from the central cylinder.
Cortical vascular bundles show anatomical diversity
amongst the genera examined. However, they can usually be recognized in single sections by the relatively
small amount of vascular tissue as compared to that of
leaf traces. The latter tend to be wider and if they are
persistent they are located nearer to the central cylinder. In many Caladieae with a cortical vascular system,
the cortical bundles are narrow and form a highly anastomosing system, as in Chlorospatha longipoda and
Xanthosoma tarapotense. Laticifers are typically present
and are associated with the phloem in Caladium,
Dieffenbachia, Philodendron and Xanthosoma.
The ground tissue of the cortex generally consists
of unlignified parenchyma with small intercellular
spaces, except in aquatic genera such as Calla and
Montrichardia, where a more extensive system of
schizogenous intercellular spaces develops.
V E G E TAT I V E A N ATO M Y
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1-22 Section A Acro 18/7/97 8:01 Page 14
Trichosclereids typically develop in the intercellular
spaces of subfamily Monsteroideae, Pothos and
Pothoidium (French & Tomlinson 1981a). Chloroplasts
are present in the ground tissue beneath the epidermis. A continuous ring or separate strands of
collenchyma may develop in the peripheral cortex
of only certain genera, including Syngonium (Birdsey
1955), Dieffenbachia (Tieghem 1867), Aglaonema,
Asterostigma,
Homalomena,
Philodendron,
Schismatoglottis, Spathantheum and Zantedeschia
(Engler 1920b). A wide variety of secretory tissues is
present, including resin and mucilage canals and cavities, laticifers and a variety of idioblasts. Many of
these structures also occur in other parts of the plant
and are discussed later.
The inner boundary of the stem cortex is sometimes demarcated by an endodermis with casparian
strips, and has been described from Rhaphidophora
celatocaulis (= R. korthalsii) (Solereder & Meyer
1928), Scindapsus pictus and Anthurium (Solereder &
Meyer 1928) as well as various species of Amydrium,
Monstera, Orontium, Rhaphidophora, Spathiphyllum,
Symplocarpus, tribe Schismatoglottideae, tribe
Peltandreae and Pistia (French & Tomlinson 1981a–d,
1983). There is some positive correlation between
the aquatic and rhizomatous habits and the occurrence of an endodermis, but there are also aquatic
genera that lack an endodermis, including Calla,
Cryptocoryne and Lagenandra. Stem endodermis has
been sought in the majority of Araceae genera and
shown to be absent (French & Tomlinson 1980,
1981a–d, 1983, 1984).
When an endodermis is present it may have several patterns of distribution, including unusual types
(French & Tomlinson 1981a–d, 1983). It may encircle
the entire central cylinder, interrupted only where
leaf traces depart, as in Orontium and Symplocarpus.
In Scindapsus and Rhaphidophora the endodermis
may develop only on the ventral side of the central
cylinder, in association with a vascular plexus of root
traces to which the roots attach. An unusual pattern
is found in tribes Schismatoglottideae and
Peltandreae. The endodermis with casparian strips
has two different patterns in these tribes: 1) it surrounds only the individual peripheral axial bundles of
the central cylinder (i.e. no endodermis is present
around interior bundles or around the entire central
cylinder), or 2) it surrounds all of the axial bundles of
the central cylinder but does not surround the entire
central cylinder or individual leaf traces. The first pattern occurs in some species of Schismatoglottis,
Hottarum and Typhonodorum. The second is present
in some species of Aridarum, Bucephalandra,
Peltandra, Phymatarum, Piptospatha and Schismatoglottis. The occurrence of an endodermis around
individual vascular bundles is unusual in angiosperms
(cf. Gunnera) but does occur in some ferns and in
Equisetum (Esau 1965).
14
THE GENERA OF ARACEAE
Organization of stem central cylinder
The central cylinder contains ground tissue and vascular bundles that are generally dispersed throughout.
In many species, the bundles are somewhat more
closely spaced towards the periphery and have a
smaller diameter than those closer to the centre of the
axis. The ground tissue is rarely lignified except in
Pothos, Pothoidium, Heteropsis and in Philodendron
subgen. Pteromischum, where usually the peripheral
and sometimes the entire ground tissue is lignified. A
wide range of secretory elements and idioblastic cells
occurs both in the ground tissue and in association
with the vascular tissue.
The general principles of vascular organization in
Araceae follow those of palms and other monocotyledons (Zimmermann & Tomlinson 1967). According to
these concepts there are two kinds of vascular bundles
in the central cylinder: 1) leaf traces that ultimately
enter a leaf when followed distally, and 2) axial bundles that remain in the central cylinder. The leaf traces
have protoxylem, which easily distinguishes them from
axial bundles, which have only metaxylem. Leaf traces
of some genera such as Cercestis and Syngonium can
be distinguished from axial bundles by the presence of
associated laticifers (French & Tomlinson 1981c, 1983).
Leaf traces have a collateral organization throughout
the family.
Four general types of axial bundles can be recognized: simple collateral bundles, compound bundles,
intermediate forms between compound and
amphivasal bundles, and amphivasal bundles, including frequently branched forms that seldom have a
complete cylinder of xylem. There is a structural continuum between all four categories (Tieghem 1867,
French & Tomlinson 1981a–d, 1983, 1984). Compound
bundles in Araceae were first observed by Tieghem. He
correctly interpreted the presence of these in some
species of Philodendron and in Dieffenbachia (French
& Tomlinson 1981d, 1984), but did not investigate
Montrichardia, Rhodospatha and Stenospermation,
which also have compound bundles.
Tieghem thought that all Araceae with unisexual
flowers had compound bundles. However, in virtually
all cases, e.g. Syngonium (French & Tomlinson 1983),
these are not true compound bundles but various types
of amphivasal bundles that branch and anastomose
among themselves. The essential difference between
the two types hinges on whether the distinct vascular
components can be recognized, as in compound bundles, or whether the xylem elements tend to form a
cylinder surrounding a core of phloem, as in amphivasal
bundles. In most genera the distinction is clear.
However, in Philodendron a wide array of bundle organization is present from simple collateral to compound
and amphivasal (French & Tomlinson 1984), and
numerous intermediate types are also present. Axial
bundles in Dieffenbachia show a similar variation in
organization and cannot readily be categorized.
1-22 Section A Acro 18/7/97 8:01 Page 15
Simple collateral axial bundles occur infrequently in
Araceae and tend to be present in genera with bisexual flowers (Tieghem 1867), although there are
numerous exceptions. From the systematic and morphological viewpoints, the distribution of collateral
bundles is interesting. They occur in all genera with
bisexual perigoniate flowers except Gymnostachys,
tribe Spathiphylleae, and subfamilies Orontioideae and
Lasioideae. Most genera with collateral bundles have
elongated internodes and many are climbers. Most
genera with bisexual perigoniate flowers but lacking
collateral bundles, such as Spathiphyllum,
Holochlamys, subfamily Orontioideae, most Lasioideae
and Gymnostachys, have relatively congested internodes, suggesting a strong correlation between this type
of vascular bundle and habit. Except for Philodendron
and Syngonium, Araceae with unisexual flowers are
rarely scandent and amphivasal bundles predominate.
Exceptions include collateral bundles in the climbing
or prostrate plants of the genera Culcasia and Cercestis.
The presence of collateral bundles tends to be correlated with prominent sclerenchyma sheaths, which are
well developed in many species. Considerable sclerenchyma occurs in the rigid stems of Pothos,
Pothoidium, Heteropsis and Philodendron subgen.
Pteromischum. The habit of these genera is also distinctive in the Araceae because the climbing stems
give rise to lateral branches which arch outward and
hang down forming shrubby or tangled masses of
branches. It is possible that increased stem rigidity in
these genera is functionally correlated with their habit
(Grayum 1984).
The second major type of vascular bundle in Araceae
is the compound bundle, recognized by Tieghem (1867),
which typically consists of two to five or more simple
collateral bundles clustered together within a common
bundle sheath. Two major characters are used to identify the compound bundle. First, component vascular
bundles tend to remain clustered as they follow a common course through the stem, although the distance
over which the components remain together is variable.
Second, individual components consist of discrete collateral bundles with their phloem strands directed
towards the centre of the cluster. In some Araceae there
are compound bundles with discrete components that
remain together over relatively long distances, as in
Rhodospatha (except R. venosa), Montrichardia,
Philodendron (some sections only), Stenospermation
and Dieffenbachia (some species).
In other Araceae there are complexes of vascular
tissue that migrate together but have less discrete components, in that the phloem tends to form a solid core
rather than separate strands. Examples include
Zamioculcas, adult stems of Cercestis, many species of
Philodendron and some species of Dieffenbachia.
These examples lead to the conclusion that it is not
possible to precisely circumscribe compound bundles
from a structural viewpoint, since there is a continuous
intergradation with amphivasal bundles.
Typical amphivasal bundles with a core of phloem
that is irregular or circular in transverse section are
also present in Acorus and Araceae, as in many
Colocasieae and Caladieae. The phloem is surrounded by xylem that contains tracheary elements
having variable patterns of organization; they may be
relatively narrow and contiguous (Cryptocoryne) or
exist as individual elements, or clusters that have variable spacing (Philodendron).
Course of vascular bundles
The three-dimensional organization of stem vasculature
of Acorus and about sixty genera of Araceae has been
analyzed using cinematic techniques (French &
Tomlinson 1980, 1981a–d, 1983, 1984). These methods
are necessary to understand the complex organization
of stem vasculature in monocotyledons, which contains numerous vascular bundles in a dispersed
arrangement. A wide range of types of organization
was revealed and these can be grouped conveniently
into four patterns.
Pattern 1 is similar to that of some palms such as
Rhapis (Zimmermann & Tomlinson 1967), and involves
a continuing axial bundle apparently following a sigmoid curve through the axis, giving rise to branches
which become leaf traces as they bend towards the
periphery. Developmental studies in palms have shown
that the leaf trace actually branches to form the continuing axial bundle. The Rhapis-type pattern occurs in
Acorus, which has amphivasal bundles (Mangin 1880).
Mangin’s remarkable study is probably the earliest
accurate account of the “palm” pattern in monocotyledons and has unfortunately been long neglected.
In Acorus, axial bundles tend to become part of a
branched network of peripheral vascular bundles after
the departure of leaf traces. This pattern has also been
observed in palms such as Chamaedorea.
The palm type occurs in Anthurium polyschistum
and the rhizome of Spathiphyllum cannifolium, which
both have simple collateral bundles (French &
Tomlinson 1981a). Culcasia saxatilis and Philodendron
hederaceum also have this basic organization.
Pattern 2 is generally similar to the palm type
because at regular intervals a continuing axial bundle
branches from the leaf trace. The principal difference
is the occurrence of unpredictable branching and anastomosis of axial bundles between departures of leaf
traces. This pattern occurs widely in Araceae. It is
present in subfamilies Calloideae and Orontioideae,
most Lasioideae, and most Aroideae (French &
Tomlinson 1980, 1981a–d, 1983, 1984). Highly condensed pattern 2 vascular systems are typical of
species with tuberous stems and rhizomes, or erect
stems with condensed nodes, which are common in
subfamilies Lasioideae and Aroideae. Individual axial
bundles in pattern 2 typically have some variation of
the amphivasal pattern of organization.
V E G E TAT I V E A N ATO M Y
15
1-22 Section A Acro 18/7/97 8:01 Page 16
Pattern 3 exhibits a relatively distinct organization
and is restricted to a few genera of Araceae. It has not
been described in any other monocotyledon. The basic
feature of pattern 3 involves the formation of a series
of narrow “bridges”, or lateral branches from both leaf
traces and axial bundles basally, which then aggregate
to form a new axial bundle that distally departs as a leaf
trace into a leaf. The pattern is referred to as the “basal
aggregation” type because axial bundles appear to arise
by the aggregation of a series of bridges or branches.
Basal aggregation occurs in Anadendrum, Pothoidium,
Pothos and certain Monstereae, including Amydrium,
Epipremnum, Monstera, Rhaphidophora, and
Scindapsus.
Pattern 4 includes a relatively small number of genera with distinct compound vascular bundles, including
Dieffenbachia, Montrichardia, Rhodospatha (all but
R. venosa), Stenospermation, some Philodendron spp.,
and genera such as Cercestis and Zamioculcas, with
intermediate conditions.
In the compound bundles of Montrichardia,
Philodendron, Rhodospatha and Stenospermation, the
individual components are relatively distinct and can
remain independent over several millimetres. A predictable pattern of changes in course and number of
components in a bundle was not detected, in contrast
to the compound bundles of Cyclanthaceae (French,
Clancy & Tomlinson 1983) and Pandanaceae
(Zimmermann, Tomlinson & LeClaire 1974).
Components may fuse together laterally, separate from
the compound bundle or may split apart in various
patterns. New bundles may be added from surrounding compound or simple bundles. In these genera there
is an apparently random series of interchanges
between components both within one bundle and
between adjacent bundles. This unpredictable feature
also occurs in Dieffenbachia, in which sclerenchyma is
minimal and bundle components are not well separated in some species.
In Dieffenbachia and in some Philodendron
species there are closely spaced bifurcations of bundles and loose association of components, which
intergrade with amphivasal bundles. A similar situation
exists in Cercestis (adult stem) and in Zamioculcas.
occur in climbing Cyclanthaceae (French, Clancy &
Tomlinson 1983).
Three major patterns of bud trace insertion are recognizable in the Araceae. In the first pattern two clusters
of bud traces follow an arching course from the bud
into the central cylinder and through the subperipheral
or peripheral area. The second pattern also involves the
formation of distinct clusters, but these migrate around
the outside of the central cylinder in the inner cortex.
They subsequently enter the central cylinder with leaf
traces and often form a cluster around an individual
trace. The third pattern is largely inconspicuous and
nondescript. It involves the fusion of a few traces
directly with the surface bundles of the central cylinder
opposite the bud. This pattern can intergrade with the
first type and is typically associated with the rhizomatous or tuberous habit. The formation of extensive bud
trace systems (patterns 1 and 2) in climbing species of
Araceae appears to be an adaptation which ensures
adequate vascular connections with lateral branches
that have no other immediate source of nutrients.
Internode development
This has been studied in a small number of climbing species, using measurements of cell length, mitotic
index and marking studies of elongating internodes
(Fisher & French 1976, 1978, French & Fisher 1977b,
French 1977). The stems of these Araceae contain socalled uninterrupted meristems, in which an acropetal
wave of cell maturation proceeds through successive
internodes, involving an end to cell division, an abrupt
increase in cell length, and ultimately cessation of
growth. Marking experiments show that elongation
continues for a longer time and at a slightly higher
rate in the upper region of the internodes of
Anthurium, Epipremnum and Philodendron, leading to
differential growth of the upper region (French &
Fisher 1977b, French 1977).
Leaf
Epidermis
Bud traces
Both the organization of bud traces and their pattern
of insertion into the main axis vary considerably in
Araceae. There are systematic correlations as well as
associations with the basic biology of stem growth.
Unfortunately this subject has not received much
study in monocotyledons so there is minimal information for broad comparisons. While most Araceae
have one bud per node, some, like Xanthosoma and
Dracontium, develop multiple buds and others like
Remusatia produce bulbils (Engler 1920b, Möbius
1935). Some similar types of bud trace insertion also
16
THE GENERA OF ARACEAE
Trichomes and larger emergences such as prickles
are highly unusual in leaves or stems of Araceae
(Solereder & Meyer 1928, Grayum 1984) and detailed
anatomical descriptions are usually lacking. Unicellular
hairs occur in some species of Xanthosoma (e.g. X.
pubescens) and short 2-celled hairs are reported for
Anubias barteri (Solereder & Meyer 1928). Multicellular hairs occur in abundance on leaves and stems of
some neotropical Homalomena species (section
Curmeria), a few species of Schismatoglottis and in
Pistia. Trichomes are also reported for leaves of
Bognera (Madison 1980), Callopsis, and some species
1-22 Section A Acro 18/7/97 8:01 Page 17
of Stylochaeton (Bogner 1984c, Mayo 1985a) but
detailed anatomical details are not available. Large,
scale-like or filamentous emergences are present on
leaves of some species of Philodendron section
Philodendron (syn. sect. Polyspermium) (Krause 1913,
Engler 1920b). Scale-like emergences are found on
stems of Syngonium podophyllum var. peliocladum
(Birdsey 1955, Croat 1982). The petioles, leaf blades
and stems of some genera are armed with sharp prickles, as in Anchomanes, Cyrtosperma, Lasia,
Lasimorpha, Podolasia, Pseudohydrosme and occasionally Nephthytis (Grayum 1984). Some neotropical
species of Homalomena have numerous recurved
prickles on their petioles. Prickle-like emergences also
occur on the stem of Montrichardia (Engler 1911, 1912,
1920b).
The cuticle of Araceae varies considerably in thickness and morphology (Solereder & Meyer 1928), but no
systematic study has been made. Cuticular ridges occur
in a number of genera including Culcasia,
Dieffenbachia, Peltandra, Pothos, Spathiphyllum and
others (Dalitzsch 1886, Webber 1960, Pant & Kidwai
1966). One or both leaf surfaces may have ridges. Waxy
deposits on the epidermis have been reported from
Caladium, Colocasia, Lagenandra, Remusatia
(Gonatanthus) (Solereder & Meyer 1928), Syngonium
(Birdsey 1955), Carlephyton glaucophyllum and
Xanthosoma violaceum (Bogner pers. comm.). The
types of wax crystalloids in Araceae have a greater
similarity to those of dicotyledons than monocotyledons (Behnke & Barthlott 1983). Hydrophilic globules
occur on the upper epidermis of Orontium and lower
epidermis of Peltandra. Franke (1967) and MaierMaercker (1981) have studied transpiration through
the cell walls and cuticle of Zantedeschia.
The organization of stomatal guard and subsidiary
cells in the leaves of Araceae has been partially surveyed in mature leaves (Dalitzsch 1886, Solereder &
Meyer 1928, Webber 1960, Pant & Kidwai 1966, Bunting
1968, Grear 1973, Grau 1983). Not surprisingly, there is
great variability in the number of subsidiary cells between
taxa and among individuals. The range is from zero
(anomocytic) as in Orontium, to two (paracytic), or four
to eight (tetracytic) in Rhaphidophora (a more complete
list is given by Grayum 1984). The development of subsidiary cells in Araceae appears to follow the perigenous
pattern, that is, to have guard and subsidiary cells from
the same parent cell, which is typical of monocotyledons.
Very few aroid stomata have been examined developmentally, however, which prevents the application of
Tomlinson’s (1974) developmental system of classification. Araceae lack the “oblique” cell divisions found in
other monocotyledons such as palms (Tomlinson 1974).
In the leaves of most aroids the stomata are either
present only on the abaxial surface (hypostomatic) or
are largely concentrated there (see Grayum 1984 for
a complete list). Shaw (1993) has studied the distribution of stomata on the leaves of Monstera deliciosa.
In Pistia the leaves are largely epistomatic, i.e. stom-
ata are present on the adaxial surface only, while
Orontium is entirely epistomatic. The guard cells are
typically level with the other cells of the epidermis,
but they may also be sunken, as in Orontium,
Ariopsis and Pistia.
Ground epidermal cells tend to have a polygonal
outline, with 5–8 straight sides and the surface usually
lacks papillae or trichomes. Undulate cell walls occur in
one or both epidermal layers and over all or part of the
anticlinal walls in a few genera. Exceptionally wide
ground epidermal cells reaching 94 µm in width occur
in Zamioculcas, whereas in other Araceae they range
from 36–71 µm (Pant & Kidwai 1966). Epidermal cells
of some genera are papillate, giving the leaves a velvety
sheen (Dalitzsch 1886, Engler 1920b, Solereder & Meyer
1928, Birdsey 1955). The papillate epidermis of the
spathe of Arum *is highly unusual in having intercellular spaces between the epidermal cells. This feature is
part of a syndrome of adaptive characters linked to the
pollination mechanism and is correlated with the
absence of stomata in the spathe (Knoll 1923).
Leaf mesophyll
The mesophyll of Araceae is predominantly bifacial,
with a thicker spongy layer below the palisade (Dalitzsch 1886). Isobilateral leaves are rare and include
some species of Anthurium and Montrichardia in
which the spongy layer is virtually absent and the palisade is nearly uniform. In Typhonodorum two palisade
layers are separated by a region of aerenchyma. Acorus
calamus (Acoraceae) exhibits a band of 3–5 layers of
chlorophyllous isodiametric cells beneath the epidermis, and a central region of large air cavities, which
significantly vary in size in different populations
(Kaplan 1970, Röst 1979b).
The palisade parenchyma cells are generally short,
relatively wide and may have arms, as for example in
Gonatopus (Solereder & Meyer 1928). Long narrow
palisade cells are of more limited occurrence and have
been observed in some species of Anthurium
(Dalitzsch 1886, Solereder & Meyer 1928).
The spongy mesophyll consists of flattened cells
with arms that are arranged in tiers, as in Anthurium
and Anubias. The spongy mesophyll has a distinctive
chambered structure in leaves of many species of
Homalomena,
Philodendron,
Piptospatha,
Schismatoglottis and Typhonium (Engler 1920b, Solereder
& Meyer 1928, Bunting 1968). In Typhonodorum stellate
parenchyma occurs in the partitions of such chambers.
In some Araceae, a hypodermis is present, consisting of one to several layers of parenchyma cells lacking
chloroplasts, as in Anthurium and other genera
(Dalitzsch 1886, Solereder & Meyer 1928). In
Philodendron Engler (1912) reported a cell layer without chloroplasts containing a red pigment lying
adjacent to the lower epidermis. Williams (1994) made
a more recent study of some Philodendron species.
V E G E TAT I V E A N ATO M Y
17
1-22 Section A Acro 18/7/97 8:01 Page 18
Leaf vasculature
Early studies of leaf venation by Engler led him to
conclude that it was not a highly significant character
for the classification of Araceae (Engler 1920b).
Nevertheless, he used venation as a major character in
the definition of his subfamilies, especially his
Philodendroideae and Aroideae (Engler 1920b), with
parallel-pinnate and reticulate venation respectively.
Ertl (1932), based on a survey of over 40 genera,
developed an explanation for the apparently variable
nature of venation in Araceae based on differences in
spacing between the primary lateral veins. No detailed
study has been made since, and although Hotta (1971)
essentially endorsed Ertl’s conclusions, this hypothesis must be regarded as tentative. Ertl concluded that
overall leaf size and shape, that is, broad versus linear,
as well as degree of dissection, have an important
relationship to venation pattern. Although these morphological and developmental correlations are
important, systematic position is also significant. Some
groups, such as tribes Colocasieae and Caladieae,
have a characteristic venation pattern that is independent of leaf shape. In these tribes there is a tendency
for quaternary veins to arch over tertiary veins (Ertl
1932, Birdsey 1955).
Ertl identified two extremes of venation pattern,
Groups I and II, and an intermediate Group III. The
continuous intergradation between the extremes is
used as an argument for a single basic plan for araceous vasculature. Group I has basically parallel or
parallel-pinnate (striate) venation and contains
Gymnostachys, Calla, some Monsteroideae such as
Stenospermation and Spathiphyllum, and the tribes of
Aroideae grouped by Engler (1920b) into subfamily
Philodendroideae (Aglaonemateae, Anubiadeae,
Dieffenbachieae, Homalomeneae, Peltandreae,
Philodendreae, Schismatoglottideae and Zantedeschieae),
together with tribes Cryptocoryneae and Ambrosineae.
Group II has a reticulate pattern, superficially like
that of dicotyledons, and includes Anthurium, subfamily Lasioideae, and most other tribes of subfamily
Aroideae including Pistieae. Group III contains
Pothos, some Monsteroideae such as Monstera, and
tribes Caladieae and Colocasieae. Ertl’s work was a
pioneering study and there is a need for a new study
of leaf venation using modern terminology and a
broad taxonomic approach.
Araceae petioles contain a variety of arrangements
of vascular bundles but no detailed systematic comparison has been made. Transverse sections of
petioles are shown in works by Engler (1905, 1911,
1912, 1915, 1920a, b), Ertl (1932), Troll (1939) and
Birdsey (1955). The mechanical support tissue of the
petiole may be in the form of a continuous peripheral ring as in Aster ostigma, Homalomena,
Montrichardia, Philodendron, Spathantheum, or separate peripheral strands of collenchyma as in
Anchomanes,
Dieffenbachia,
Dracontium,
18
THE GENERA OF ARACEAE
Philodendron, Schismatoglottis, Zantedeschia and
most Caladieae and Colocasieae (Dalitzsch 1886,
Birdsey 1955). In some genera such as Amorphophallus and Pseudodracontium, the vascular bundles
have collenchymatous bundle sheaths (Dalitzsch
1886). In others, the support tissue is primarily bundle sheath sclerenchyma and may be fused together
to form a peripheral layer (Anthurium,
Rhaphidophora, Spathiphyllum). Fibre bundles may
be present, with or without phloem, as in
Anthurium. The vascular bundles may be rather distant from one another and have large sclerenchyma
sheaths, as in Cyrtosperma and Lasia. In Orontium
and Calla mechanical tissue is absent from the petiole (Solereder & Meyer 1928).
Leaf tubercles and regeneration
Tubercles regularly develop at the juncture of leaflet
and petiole in Pinellia ternata (Hansen 1881, Linsbauer
1934, Troll 1939), at the apical end of petiole in
Typhonium bulbiferum (Sriboonma et al. 1994) and at the
first and second order divisions of the leaf of
Amorphophallus bulbifer (Troll 1939). Tubercles in
Pinellia may also form spontaneously along the petiole
or can be induced in the basal part by cutting into segments (Linsbauer 1934). Tubercles may develop in
Typhonium violifolium at the leaf apex, the petiole apex
and at the apex of the sheath (Sriboonma et al. 1994).
Regeneration of tubers, leaves and roots from leaf
segments is well known in Zamioculcas zamiifolia
and Gonatopus boivinii (Engler 1881, Schubert 1913,
Cutter 1962). Isolated entire leaflets of Zamioculcas
and Gonatopus spontaneously develop a basal
swelling, followed by the formation of roots and up to
3 buds, over a 6–9 week period for Zamioculcas. Leaf
regeneration in Gonatopus is more rapid. The results
of experimental manipulation of isolated leaflets grown
in culture show that any part of the compound leaf is
capable of regeneration, and that new shoots arise in
association with the cut ends of the largest veins, preferentially at the proximal end. When midvein tissue is
present, regeneration at lateral veins is absent, even
though there is no vascular connection with the midvein. When only lateral veins are present, regeneration
proceeds at their proximal ends (Cutter 1962). Plantlets
may also regenerate from leaf blades in
Schismatoglottis (Bogner, pers. obs.).
Geniculi (pulvini)
A pulvinus (swelling) or geniculum (joint) occurs
at the distal end of the petiole in nearly all Pothoideae,
Monsteroideae and certain Aroideae (Anubias,
Bognera, tribes Culcasieae, Zamioculcadeae, rarely in
Philodendron and Homalomena). Details are given in
the generic and tribal descriptions in this volume. The
1-22 Section A Acro 18/7/97 8:01 Page 19
mechanical tissue in the geniculum consists of collenchyma in a peripheral ring or collenchymatous
bundle sheaths, whereas elsewhere in the petiole it is
formed by sclerenchyma (Dufour 1886, Dalitzsch
1886). The petiole of Gonatopus boivinii has a geniculum in the middle which can reorient the blade. Some
reorientation is also possible from a second geniculum
near the base of the leaf (Troll 1939).
Ligules
Ligules were regarded by Engler as a modified leaf
sheath with a free extension at its tip. They occur in
Calla, various Schismatoglottideae, Dieffenbachia and
some species of Philodendron. A membranous “stipule” has been reported in Pistia (Engler 1920a).
Leaf structure of Acorus (Acoraceae)
Much attention has been devoted to the leaf of
Acorus, especially to its early development. Kaplan
(1970) presented several conclusions based on a rigorous comparative developmental study of Acorus. He
concluded that its unifacial leaves are distinct from
those of the Araceae because of the intense adaxial
meristematic activity that begins during apical growth.
Adaxial growth leads to a “bulge” that arches over the
shoot apex. The leaf of Acorus is thus a foliar structure
and not a flattened petiole.
Earlier workers mistakenly interpreted young leaves
as having two successive apices, one that led to a
hyponastic arching primordium and a second that overtopped the original, a pattern referred to as sympodial
growth. Kaplan (1970) observed that continued adaxial meristematic activity and suppression of the
marginal meristems leads to the formation of the radially flattened leaf. A narrow secondary midrib does,
however, develop. Morphologically and developmentally the leaf of Acorus is similar to the phyllode of
Acacia, which also develops an active adaxial meristem. The phyllode theory of Arber, which attempted to
interpret leaves of Acorus as flattened petioles, is thus
based on an erroneous interpretation.
It is interesting that leaves of different populations
of Acorus calamus studied by Kaplan (1970) differ in
their degree of apical growth, which is correlated with
radial expansion. The Iowa population (probably a
diploid) exhibited more prolonged apical growth and
less radial growth than the Wisconsin population
(probably a triploid). One would predict that the
tetraploid should exhibit even shorter apical growth
and greater radial expansion. Vascular differentiation in
the leaf of Acorus begins first in the centre of the axis
and later is bidirectional, as is the activity of a plate
meristem at the leaf margins. Subsequent growth in
length is accomplished predominantly through the
activity of a basal intercalary meristem.
The leaf anatomy of Acorus has received much
attention (Dalitzsch 1886, Solereder & Meyer 1928, Ertl
1932, Kaplan 1970, 1973a). Röst (1979b) was particularly
interested in the biosystematics of Acorus calamus and
A. gramineus and he discriminated between the two
using a variety of leaf characters, including the organization of chlorenchyma, aerenchyma and sclerenchyma.
Three morphologically distinct varieties of A. calamus
are recognized (Röst 1979b). Each can be distinguished
by ploidy level and on the basis of one leaf characteristic, namely the number of air canals in a prescribed area
of a transverse section (0.62mm2) of the lamina above the
sheath (Röst 1979b). The diploid variety has relatively few
canals (less than 17), the tetraploid has numerous canals
(more than 77), and the triploid variety is intermediate
(26–51 canals). Using Röst’s criteria it appears that
Kaplan’s (1970) Iowa population is the native American
diploid (Acorus calamus var. americanus) and the
Wisconsin population is the triploid (A. calamus var.
calamus). No tetraploids were studied by Kaplan (1970).
The triploid is sterile, mainly Eurasian, and probably was
introduced to North America by European settlers.
Special Topics
Trichosclereids
These are filamentous, branched sclerenchyma cells
(sclereids) up to 7 mm long which develop in the
intercellular spaces of vegetative and floral tissues of all
genera of subfamily Monsteroideae except Anadendrum
and Heteropsis, and two genera of subfamily Pothoideae,
Pothos (Tieghem 1867, Engler 1920, Solereder & Meyer
1928, Nicolson 1959) and Pothoidium (French &
Tomlinson 1981a). Trichosclereids rarely develop in
roots. They played a significant role in Engler’s classification of the Araceae, which emphasized vegetative
anatomical features.
The term trichosclereid was first applied by Bloch
(1946) and Sinnott & Bloch (1946) in their classic
study of idioblast development in Monstera deliciosa.
A variety of other terms had been used previously
including “raphide”, which was in common use in the
early 19th century to refer to anything needle-shaped
(Nicolson 1959, 1960b). The term was confusing
because raphides of calcium oxalate, which are crystals, also occur in the same tissue. Schott correctly
illustrated trichosclereids in various monsteroid genera, but referred to them as “raphides” (Schott 1832,
Schott 1858). Hasskarl (1842) carried this confusion
one step further by naming a monsteroid genus
Rhaphidophora on the basis of correctly illustrated
trichosclereids.
Schleiden (1839) correctly identified “raphides” (=
trichosclereids) as “Bastzellen”, and more detailed
accounts by other anatomists followed (Sueur 1866,
Tieghem 1867, Wiesner 1875). Tieghem (1867) made
V E G E TAT I V E A N ATO M Y
19
1-22 Section A Acro 18/7/97 8:01 Page 20
a number of observations of trichosclereids as part of
a general survey of the anatomy of the Araceae, and
was the first to notice that they occurred primarily in
monsteroid taxa, an observation used by Engler in
defining subfamily Monsteroideae taxonomically
(Engler 1920b). However, Engler emphasized the
presence of trichosclereids to such an extent that he
placed several genera which lack these cells but otherwise display clear monsteroid affinities in his
subfamily Pothoideae. These genera, which included
Anadendrum, Epipremnopsis (= Amydrium) and
Heteropsis, are today widely recognized as belonging
to subfamily Monsteroideae (Nicolson 1984a, Bogner
& Nicolson 1991, this volume), and trichosclereids
are now known to occur in Amydrium.
As a result of various studies, a rather general
understanding of the morphology, occurrence and
development of trichosclereids has emerged (Nicolson
1960b). In the Araceae, trichosclereids have several
distinctive features although there is considerable
quantitative variation among species. They begin
development as small, nearly isodiametric cells which
form 1–4 hair-like outgrowths that elongate into the
surrounding tissue, forming an irregular network
within the intercellular spaces. Their branches grow
apically, are often of irregular shape and may themselves branch.
Trichosclereids that have two branches have a peglike central body which identifies the location of the
original cell and is the site of attachment in the tissue.
In contrast, other types of sclereid, such as libriform
fibres, may be long and filamentous but do not have
branches arising from a cell body. Trichosclereids may
also have four outgrowths resulting in an H-shape.
The number, diameter and length of the branches are
the primary sources of variation. In Spathiphyllum trichosclereids appear to be longer and narrower than
those from Rhaphidophora and other Monstereae
(Tieghem 1867, Nicolson 1960b). It has long been recognized that in tribe Spathiphylleae there are more
numerous trichosclereids in each intercellular space
than in tribe Monstereae. Estimates of over 50
(Solereder & Meyer 1928) and between 15–20
(Nicolson 1960b) have been made. This contrasts
greatly with the 1–4 trichosclereids in each intercellular space found in tribe Monstereae (Nicolson 1959). In
addition, some trichosclereids intergrade with astrosclereids in foliage leaves, e.g. in Monstera.
The distribution of trichosclereids in the plant body
follows a general pattern throughout subfamily
Monsteroideae (sensu Engler 1920b). They are usually
present in the stem, petiole, leaf blade and inflorescence, but have been reported in the roots in only
three species (Solereder & Meyer 1928). It is not
uncommon for trichosclereids to be absent from one
part of the plant body (Nicolson 1959, 1960b). In some
Epipremnum species and Monstera punctulata, trichosclereids are absent from the leaf blade (Nicolson
1959, Madison 1977a).
20
THE GENERA OF ARACEAE
Laticifers
Early studies (Hanstein 1864, Trécul 1865, 1866)
demonstrated the presence of articulated non-anastomosing laticifers in most subfamilies, including
Calloideae, Lasioideae, Orontioideae and Aroideae, and
articulated, anastomosing laticifers in tribes Caladieae
and Colocasieae (except Ariopsis). Both clear and milky
latex was described by early workers, who detected
abundant tannins in the latex. The clear, tannin-rich
latex of some Araceae has been compared with the
exudate produced by articulated cells in the phloem of
some Leguminosae (Trécul 1865, 1866, Esau 1974),
which may also have perforated end walls.
All early workers considered Araceae to have laticifers that produce latex. However, Solereder &
Meyer (1928) took a more neutral position, refraining
from the use of the term laticifers. They used the
terms “secretory files” or “secretory tubes” to describe
the non-anastomosing and anastomosing laticifers,
respectively.
Engler (1920b) emphasized the presence of anastomosing laticifers in defining his subfamily
Colocasioideae (equivalent to our tribes Caladieae and
Colocasieae combined). However, Weiss (1866) found
that non-anastomosing laticifers are present in roots of
Syngonium; he made no further observations on other
genera of Engler’s subfamily Colocasioideae. Engler
(1920b) also defined his subfamilies Pothoideae and
Monsteroideae in part because of their lack of laticifers.
Individual “secretory” cells, not arranged in files, are
present in these taxa, but their chemical and structural
similarity to laticifers remains unstudied.
Laticifers in Araceae typically occur in association
with vascular bundles, lying on the periphery of the
phloem in the leaf and stem. In stems, laticifers occur
only in leaf traces or cortical bundles, not in axial
bundles (French & Tomlinson 1981c–d, 1983). In
roots, laticifers also occur in association with phloem,
but may be present in the xylem, pericycle or ground
tissue (Weiss 1866, Lierau 1888). They are visible in
sections because of dark-staining contents and a relatively wide lumen compared to adjacent phloem
cells. Laticifers may occur in the root cortex in
Philodendron and various Caladieae and Colocasieae
(Weiss 1866, Porsch 1911).
The most complete study of the systematic occurrence of laticifers is by French (1988 and unpublished
observations), who examined leaves and inflorescences
of 75 genera. Anastomosing laticifers are limited to the
tribes Caladieae, Colocasieae and Zomicarpeae.
Articulated, non-anastomosing laticifers occur in Calla,
Orontium and almost all Aroideae (except tribes
Pistieae, Stylochaetoneae, Zamioculcadeae). Tribe
Cryptocoryneae have been previously reported as lacking laticifers, but recent unpublished work has
demonstrated their presence in the stems, roots and cataphylls of both Cryptocoryne and Lagenandra, though
not in the foliage leaves (Sivadasan, pers. comm.).
1-22 Section A Acro 18/7/97 8:01 Page 21
Limited cytological observations of laticifers were
made by Molisch (1899, 1901) and Southorn (1964).
No clear picture of latex cytology has yet emerged.
Schmid (1882) observed nuclei, small dense spheres
and larger unidentified elliptical particles approximately the size of a nucleus in laticifers of Caladium.
Molisch (1899, 1901) made the most extensive
cytological study, using fresh latex. He observed socalled “Blasenkerne”, which represent nuclei having
sac-like protrusions, in several genera, including
Aglaonema, Philodendron, and Xanthosoma. Molisch
also found what he called abundant leucoplasts in the
latex of Steudnera colocasiifolia, as well as biconvex
particles (7–16 µm in diameter) of unknown identity.
In other studies Molisch (1901) noted that in latex of
Amorphophallus konjac (syn. A. rivieri), large (16 µm)
membrane-bound six-sided crystalloids are found. In
the only recent study, Southorn (1964) reports the
presence of vacuoles containing particles in Brownian
motion in Dieffenbachia. Fox & French (1988) found
that abundant terpenoid particles were responsible
for the white appearance of the latex of tribe
Caladieae, analogous to the white latex of
Euphorbiaceae. The clear or cloudy latex of tribe
Colocasieae lacks the abundant terpenoid particles.
Larger latex particles were also found in the latex of
“colocasioids” (i.e. tribes Caladieae and Colocasieae
combined), as described by Molisch, and their occurrence was found to be systematically significant
(French & Fox, unpublished results).
Resin canals and cavities
The presence of resin canals in Araceae has been
documented from the mid-nineteenth century (Trécul
1865, 1866, Tieghem 1867). However, Solereder &
Meyer (1928) proposed the neutral term “secretion
spaces” to refer to these canals in Araceae because in
their opinion there was a lack of chemical evidence for
the presence of resin. Resin typically contains large
amounts of various terpenoids and other lipophilic
substances and is thus chemically distinct from
mucilage, which is hydrophilic (Fahn 1979). It is synthesized and accumulated by canals and cavities which
are of limited occurrence in Araceae (Trécul 1865,
1866, Tieghem 1867, 1872, 1885). Resin is generally
considered to be part of the plant’s chemical defence
against herbivores.
Resin canals are composed of a central cavity surrounded by 1–3 layers of synthetically active epithelial
parenchyma. A sclerotic or collenchymatic protective
sheath may surround the epithelium (Möbius 1885).
Secretory cavities differ from canals principally in their
shape which ranges from spherical to irregular. Both
canals and cavities are reportedly schizogenous in origin (Leblois 1887, Engler 1920b). Resin canals were
first reported in Araceae by Trécul (1865, 1866) who
found them in leaves, stems and roots of Philodendron
and Homalomena species. Additional reports of resin
canals and cavities in these two genera were made by
Tieghem (1867, 1872, 1885), Möbius (1885), Dalitzsch
(1886), Leblois (1887), Lierau (1888), Went (1895),
Porsch (1911), Engler (1920b) and Pohl (1932a, b).
The most complete study is a family-wide survey by
French (1987b), which included 91 genera and 250
species and showed that resin canals occur in the roots
of only five genera, Culcasia, Cercestis, Homalomena,
Furtadoa and Philodendron. In the leaf of Culcasia the
canals are easily visible with the unaided eye and
exhibit a variety of differences in their length and orientation depending on the species (Knecht 1983). They
are also visible without magnification in leaves of
Philodendron. Recent studies have also confirmed their
presence in the stems of Culcasia, Homalomena (cavities), Philodendron, and Cercestis (French &
Tomlinson 1981a, c–d, 1983).
Pohl (1932a, b) and Mayo (1986b, 1991) investigated
the resin canals that are present in the inflorescence of
Philodendron. The resin is released onto the spathe or
spadix surface and plays a role in the floral biology in
Philodendron by glueing the pollen onto the pollinator’s
body (Gottsberger & Amaral 1984, Grayum 1990, Mayo
1991). In species of Philodendron subgen. Meconostigma
(e.g. P. bipinnatifidum studied by Pohl 1931a, b as P. selloum), one end of the canal is close to the inner surface
of the spathe and releases resin shortly before spathe closure. In Philodendron subgen. Philodendron resin is
secreted onto the spadix surface from numerous resin
canals located just below the axial epidermis, around
the bases of the stamens and staminodes. In these
species, the pollen and resin are mixed even before
appearing at the spadix surface (Mayo 1986b).
Mucilage cells, canals, and cavities
Mucilage contains various hydrophilic substances
and can readily be distinguished from resin using
appropriate histochemical procedures. It may occur in
various idioblasts such as raphide tubes (Solereder &
Meyer 1928), together with calcium oxalate crystals,
or in large mucilage cells, as in Amorphophallus
(Abranowicz 1912, Wakabayashi 1957a, b). Mucilage
also occurs in canals and cavities which may form
schizogenously, as in Epipremnum pinnatum (Leblois
1887) or lysigenously as in Colocasia (Solereder &
Meyer 1928). Mucilage canals and cavities may have a
distinct epithelium of smaller, more densely stained
cells, and some epithelial cells may project into the
locule or grow into it like a tylose (Engler 1920b).
Mucilage canals are of relatively limited occurrence in Araceae. They occur in Aglaonema,
Alloschemone, Alocasia, Anthurium, Cercestis,
Colocasia, Epipremnum, Monstera, Philodendron,
Remusatia, Rhaphidophora, and Xanthosoma
(Solereder & Meyer 1928, French & Tomlinson
1981a–d, 1983, 1984, Boyce, pers. obs.).
V E G E TAT I V E A N ATO M Y
21
1-22 Section A Acro 18/7/97 8:01 Page 22
Extrafloral nectaries and punctations
Zimmermann (1932) exhaustively reviewed the
occurrence of extrafloral nectaries in angiosperms
and listed reports of possible extrafloral nectaries in
Arisaema (Knuth 1909), Colocasia (Solereder &
Meyer 1928) and Philodendron, but nectar secretion
is listed as very doubtful. Madison (1979a, b) reported
nectar production by a ring of extrafloral nectaries at
the base of the leaf lamina in Philodendron myrmecophilum (= P. megalophyllum), and sweet secretions
are produced also by the extrafloral nectaries of prophylls in many species of Philodendron, and on the
outside of the spathe in P. goeldii (Bogner, pers.
obs.). In a description of the leaf of Araceae, Engler
(1920b) made no specific mention of extrafloral nectaries, but “sessile superficial glands” were reported
in Alocasia by Gardiner (1883, 1889) and BelinDepoux (1978). The anatomy of the “glandular”
structures in Culcasia was described by Solereder
(1919) who considered them possibly to be extrafloral nectaries (Solereder & Meyer 1928).
Solereder (1919) and others (Tieghem 1867,
Bachmann 1880, Dalitzsch 1886, Gentner 1905, Engler
1920b) have described the mature structure of the
unusual “punctations” on the leaves of various species
of Anthurium. They are often referred to as glands or
glandular punctations and Dalitzsch (1886) reported
seeing secretions released internally, but this has not
been confirmed. Each mature punctation consists of
three regions: 1) a basal region of 1–3 curved layers of
prismatic cells in files embedded in mesophyll, 2) a
central region of large, radially elongated cells lacking
dense contents, and 3) an outer cluster of compact cells
with dark brown or black contents beneath a stomate.
No secretion has been observed to exude from the surface punctations and the chemical identity of the dark
contents is unknown. Solereder (1919) pointed out the
similarity of these structures to the cork warts of some
dicotyledons, also mentioned by Bachmann (1880).
Hydathodes
Hydathodes occur in the leaf tips of many Araceae,
and have attracted considerable attention because of
the high rate of guttation in some species. Guttation
has been studied frequently in Colocasia, in which
rates of over 100 ml/day/leaf are not unusual (Molisch
1903). The hydathodes of Araceae are often localized
in the leaf tip, the “Vorläuferspitze” (precursor tip),
which contains numerous stomata on both surfaces
(Müller 1919); hydathodes may also be found elsewhere on leaves. The stomata may be relatively
normal in size and appearance, or may be larger than
surrounding stomata. The hydathode also contains
underlying ground and vascular tissue with numerous tracheids (epithem). However, Gardiner (1883)
did not regard the epithem of Calla and Zantedeschia
22
THE GENERA OF ARACEAE
as specialized or conspicuous, compared with
dicotyledons. The leaf apex and hydathodes have
been described in various species of Araceae by
Müller (1919), who recognized three types of hydathodes: the Philodendron type, with normal or slightly
larger stomata; the Alocasia type, with large stomata,
and finally the Colocasia type with gigantic macroscopic stomata through which guttation occurs.
The Philodendron type occurs in all subfamilies; the
Alocasia type is more restricted, and the Colocasia type
was found only in Ariopsis, Colocasia and Steudnera.
More complete lists have been given by Müller (1919)
and Grayum (1984). In Lasia hydathodes are present on
leaf emergences. Further details of hydathode structure
have been given by Ducharte (1859), Dalitzsch (1886),
Minden (1899) and Gentner (1905).
Intravaginal squamules
These are glandular, flattened, non-vascularized,
multicellular scales of uncertain function, ranging from
approximately 1 mm to over 25 mm in length. They
occur in the leaf axils of Acorus (Acoraceae),
Philodendron, Cryptocoryne and Lagenandra (Irmisch
1858, Engler 1912, 1920a, b, Lawalrée 1945, Ritterbusch
1971, Blanc 1978). Velenovsky (1907) reported squamules in many Araceae, which must be an error.
Similar structures also occur in Spirodela (Lemnaceae)
and in all Alismatiflorae except Scheuchzeria, where
they are replaced by hairs (Tomlinson 1982). In section,
squamules of Araceae and Alismatiflorae often have a
mucilaginous and glandular appearance (Kaplan 1973a
Tomlinson 1982). Kaplan (1973a) reported that in
Acorus, two squamules arise from the protoderm of the
axillary meristem and expand rapidly before the prophyll is initiated.
Mineral crystals and crystal idioblasts
A wide range of calcium oxalate crystals and crystalcontaining idioblasts is present in Araceae, although few
detailed studies have been made of their development,
distribution or biological significance (see Seubert 1993
for a recent study in Araceae). Mineral crystals have been
viewed both as waste products and as agents of plant
protection against herbivores (Esau 1965, Madison
1979a). Calcium oxalate crystals occur most commonly
as raphides and druses, less commonly as crystal sand,
“ styloids” or prisms Histochemical tests by Sunell &
Healey (1981) confirmed that the raphides of Colocasia
esculenta contain calcium oxalate. X-ray diffraction studies of raphides of Monstera deliciosa (Al-Rais, Myers &
Watson 1971), Xanthosoma sagittifolium (Cody & Horner
1983) and Colocasia esculenta (Sunell & Healey 1981)
demonstrated monoclinic calcium oxalate monohydrate.
Comparable studies have not been made on the other
types of presumed calcium oxalate crystals in Araceae.
1-22 Section A Acro 18/7/97 8:01 Page 23
No silica or calcium carbonate crystal inclusions have
been demonstrated. Unidentified inclusions (probably
not calcium oxalate) are present in the parenchyma of
tubers of Amorphophallus konjac (syn. A. rivieri)
(Abranowicz 1912).
The structure of raphides in Araceae is apparently
unusual in angiosperms (Cody & Horner 1983) because
they consist of twinned crystals, H-shaped in transverse section and are often barbed laterally (Sakai &
Hanson 1974). Similar shaped raphides occur in some
Lemnaceae. The systematic significance of these findings is unclear because there have been very few
general surveys of raphide structure in angiosperms
using the scanning electron microscope, which is necessary for more rigorous comparative studies.
Raphide-containing idioblasts are variable in length,
wall specialization and manner of raphide release. There
are two general types in Araceae: 1) thin-walled raphide
idioblasts, and 2) thick-walled idioblasts called biforines.
Thin-walled raphide idioblasts range in shape from isodiametric to very elongated (3–5 mm long in Monstera
deliciosa, Kovacs & Rakovan 1975). The elongated forms
have been referred to as “Raphidenschläuche” (Solereder
& Meyer 1928) and may contain many bundles of
raphides oriented at various angles and embedded in
mucilage. They are of common occurrence in Araceae
and have been reported by many authors (e.g. Dalitzsch
1886, Porsch 1911, Solereder & Meyer 1928, Hinchee
1981). The elongated type may intergrade with cells that
are much shorter at maturity and tend to grow rapidly
by apical intrusive growth, allowing them to exceed the
length of surrounding cells. There are reports of raphide
idioblasts anastomosing during development in
Anthurium scandens, A. scherzerianum and A. triphyllum (Samuels 1923) and in other genera, such as
Monstera and Dieffenbachia (Solereder & Meyer 1928).
Samuels challenged the idea that the long tubes in many
Araceae are single cells, proposing instead that they
form by the anastomosis of cells in files. No subsequent
authors have addressed this issue and Samuels’ interesting findings are unconfirmed. Raphides are reportedly
absent from Acorus (Acoraceae).
The second type of raphide idioblast is the biforine,
a term coined by Turpin (1836) to refer to spindleshaped or cylindrical cells with thick, unlignified walls
(Middendorf 1983). No specific function for these cells
has been demonstrated, but some authors have
described a “blowgun” release of raphides (Middendorf
1983). One or both ends of the cell may be blunt,
pointed or papillose, and with much thinner walls. The
thinnest part of the end wall in Colocasia esculenta is 0.1
µm thick (Sakai & Hanson 1974). The variable orientation of fibrillar material causes the cell wall to appear
layered, except in Alocasia (Sakai & Hanson 1974). The
dimensions of some biforine cells are 50 x 150 µm in
Colocasia esculenta (Sakai & Hanson 1974) and 40 x 90
µm in Alocasia. Biforines like those of Colocasia esculenta may have one end embedded in tissue and the rest
of the cell projecting into an intercellular space.
Alternatively both ends may project into separate spaces
with the middle of the cell loosely held by mesophyll
cells or vascular tissue (Sunell & Healey 1981).
The presence of mucilage in biforines has been
recognized since Turpin’s study (1836) and its swelling
is generally considered to be the motive force for the
expulsion of the contents of the biforine (Sakai &
Hanson 1974). In some species raphides are expelled
individually (Colocasia) by piercing and subsequent
rupturing of the thin papillae. In others expulsion
occurs after the papillae are ruptured by other means
(Sakai & Hanson 1974), as in Dieffenbachia. By contrast, in Alocasia the cell wall of the biforine breaks at
the base of the cell and the entire mass of crystals and
mucilage is ejected, followed by swelling and individual dispersal of the raphide crystals.
The occurrence of biforines in Araceae has been
summarized by Solereder & Meyer (1928), by Nicolson
(1959) who added many new observations, and by
Grayum (1984). No detailed family-wide survey has yet
been made, but existing data (De Bary 1884, Dalitzch
1886, Solereder & Meyer 1928, Grayum 1984) suggest
that biforines are characteristic of genera with unisexual
flowers and generally absent in bisexually-flowered genera. Among the latter, biforines have so far been observed
only in Anthurium, Orontium and Symplocarpus.
Calcium oxalate is also the major component of
druses, which have a wide systematic occurrence in the
family. Druses vary considerably in size, sometimes
reaching 90 µm in Zamioculcas (Solereder & Meyer
1928). They also vary in morphology and include atypical forms in leaves of Anthurium, Dieffenbachia, Pistia
and other genera (Solereder & Meyer 1928) and may
occur in small rounded epidermal cells in Anthurium,
Culcasia, Pothos, Schismatoglottis and many other genera. Prisms are of limited occurrence in Araceae, and
have been reported only in subfamilies Pothoideae and
Monsteroideae (Solereder & Meyer 1928, Nicolson
1959, Seubert 1993).
Developmental studies of raphide crystals and crystal-containing idioblasts have been made by Samuels
(1923), Becker & Ziegenspeck (1931), Rambour (1965),
Mollenhauer & Larson (1966), Rakovan, Kovacs &
Szujko-Lacza (1973), Kovacs & Rakovan (1975), and
Hinchee (1981). According to Kovacs & Rakovan
(1975), raphide idioblasts in Monstera arise by unequal
cell division. The smaller cell develops into the raphide
idioblast which has densely staining cytoplasm and a
larger nucleus than the surrounding cells. Hinchee
(1981), however, did not observe asymmetric divisions
giving rise to raphide idioblasts in Monstera. Kovacs &
Rakovan (1975) noted that raphides develop as soon as
the young idioblast cells are the same size as surrounding cells, before the phase of rapid elongation.
Seubert (1993) has recently carried out a survey of
crystal types occurring in the seeds of Araceae as part
of a comprehensive study of Araceae seed anatomy.
Her illustrations reveal a fascinating diversity of novel
crystal forms.
V E G E TAT I V E A N ATO M Y
23
1-22 Section A Acro 18/7/97 8:01 Page 24
Occurrence of vessels
Vessels with scalariform or reticulate perforation
plates have long been recognized in the roots of some
Araceae, such as Monstera deliciosa, and
Philodendron and Alocasia species (Solereder &
Meyer 1928, Kundu 1942), while other genera like
Caladium and Pistia have been considered vesselless (Solereder & Meyer 1928). Solereder & Meyer
were apparently the first to identify vessels in the
stems of Araceae, in Pothos scandens and P. rumphii.
In Culcasia scandens they found no vessels but tracheids with wide lumens. Later Cheadle (1942)
examined 7 genera and 8 species and found vessels in
the roots only, with scalariform perforation plates in all
species. Subsequently Hotta (1971) reported vessels in
stems of a few species, but in the roots of nearly all
those he examined except Arisaema, Homalomena,
Pothos and Rhaphidophora. Hotta’s sample was not
very broad taxonomically, but represents the most
extensive to date. Vessels occur in stems of several
species of Pothos, Epipremnum, Rhaphidophora and
Scindapsus. Hotta (1971) emphasized the difficulty
encountered in recognizing vessel members in
Araceae, principally because of the similarity between
scalariform pitting and scalariform perforations on the
long, oblique end walls of tracheids. He also referred
to some tracheids as “vesselform” tracheids because of
their similarity to vessels.
Phloem cytology
The phloem of Araceae has been examined using
light microscopy in studies by Shah & James (1971) as
well as in investigations by Lesage (1891). Recent
ultrastructural studies have been made by Behnke
(1969, 1981), Bonzi & Fabbri (1975, 1978) and
24
THE GENERA OF ARACEAE
Parthasarathy (1980). Behnke’s work on sieve element
plastids is of considerable interest. In an extensive
survey of the Araceae, Behnke (1995) confirmed the
widespread occurrence of the typically monocot plastid type P2 in the family. The Araceae have a relatively
rich array of sieve element plastid ultrastructure, with
type P2c found in 14 species and P2cfs in one species.
A P2 subtype with both cuneate protein and starch
grains was found in 110 of the 126 species surveyed.
Unexpectedly Pistia was found to have S type plastids
thus completely different from all other monocotyledons. The S type has heretofore been found only in
dicotyledons. Conversely only two dicotyledons have
been found with P2c plastids, Asarum and Saruma.
The phylogenetic significance of these findings is discussed at length by Behnke (1995).
Starch grains
Starch grain morphology in Araceae has been
examined by Reichert (1913), Czaja (1969, 1978a, b)
and Seubert (1993). Reichert reported that starch grains
in Arum, Arisaema, Dracunculus and Zantedeschia
all belonged to the same type, while in Dieffenbachia
a remarkably different kind is present. Despite gross
structural differences all five genera have starch with
similar physical and chemical properties. Reichert
(1913) also studied starch grains in Alocasia,
Amorphophallus, Peltandra and Colocasia. Those of
Peltandra were found to resemble the Dieffenbachia
type, while grains in Amorphophallus and Colocasia
were of the Arum type. Grains of Alocasia were “peculiar” and not assigned to either type. More recently,
Seubert (1993) has surveyed starch grain morphology
in Araceae seeds. Using Czaja’s terminology (Czaja
1969), she recognized 11 different types in a survey of
over 70 genera.
C
1-22 Section A Acro 18/7/97 8:02 Page 25
C
4
INFLORESCENCE AND FLORAL MORPHOLOGY
The inflorescence of the Araceae is composed of an
unbranched spike bearing flowers, the spadix, subtended by a bract called the spathe. The flowers are
usually numerous, very small, sessile in all genera
except Pedicellarum, and lack floral bracts. They are
generally spirally arranged and usually tightly packed,
although in some species of Pothos ser. Goniuri,
Pedicellarum, Amorphophallus (male and female flowers), tribe Dieffenbachieae (female flowers) and most
species of Arisaema and Arisarum (male flowers), they
may be somewhat distant from one another.
The spathe is, strictly speaking, the last leaf of a
flowering article. It is usually a specialized attractive
organ although in a few genera (Gymnostachys,
Orontium) is inconspicuous. The internode between
spathe and spadix (spadix stipe) is usually very short or
absent, while the peduncle – the internode between
spathe and last foliage leaf or cataphyll – is much
longer. In some primitive genera, however, this arrangement is reversed (Gymnostachys, subfamily
Orontioideae, some Pothos species). It seems likely that
an important stage in aroid evolution involved the combined development of a relatively long peduncle and
short stipe, modified attractive spathe and continuation
shoot development at the second node below the
spathe. Gymnostachys and subfamilies Orontioideae
and Pothoideae seem to represent earlier, less uniform
phases of organization. The typical araceous pattern
has given rise to a wide range of variant forms in different genera, which can be seen to represent an
evolutionary trend of increasing integration towards a
synflorescence or pseudanth. The major phyletic modifications are: 1) loss of perigone in the flowers; 2)
specialization of flowers on the spadix into a lower
female zone, upper male zone and, often, one or several zones of sterile flowers, entirely naked axial zones
and smooth or staminodial terminal appendices; 3) differentiation of the spathe into a lower, convolute tube
and an upper, expanded blade.
Spathe and spadix modifications are closely related
so that the spathe may be seen evolutionarily as
becoming increasingly integrated into the inflorescence itself, until in extreme cases, such as tribe
Cryptocoryneae, Ambrosina, Pistia and Pinellia, fusion
and still more elaborate modifications have brought
about division of the spathe into separate chambers.
Spathe blade
Spadix
Male zone
Flowers
Sterile zone
Stipe
Spathe constriction
Spathe
Female zone
Spathe tube
Stipe
Peduncle
Peduncle
Figure 7. Inflorescence types: A, bisexual flowered spadix with a simple, undifferentiated spathe; B, unisexual flowered spadix with a
spathe divided into a limb (blade) and convolute lower tube.
INFLORESCENCE AND FLORAL MORPHOLOGY
25
1-22 Section A Acro 18/7/97 8:02 Page 26
Other notable specializations of the inflorescence
include the wide range of odours found in different
genera, colour patterns, especially on the spathe, and
the relative persistence of different regions of the
spathe. In Philodendron, for example, the entire
spathe persists until fruit, but in tribes Colocasieae,
Caladieae, Peltandreae and Schismatoglottideae the
spathe blade withers or drops off immediately following anthesis while the spathe tube persists. In
many Monstereae the entire spathe withers or drops
off soon after flowering, a behaviour which is correlated in this tribe with the presence of numerous
protective trichosclereids in the style tissue.
Terminal appendices of the spadix are found in tribes
Areae, Arisaemateae, Colocasieae, Schismatoglottideae,
Thomsonieae and Zomicarpeae, sporadically elsewhere
in the family. The function of the appendix, where
investigated, is to produce odours to attract pollinators (osmophore, Vogel 1963, 1990). The appendix is
either clearly composed of staminodes (e.g.
Pseudodracontium) or is partially to entirely smooth
with no vestiges of floral organs (e.g. Arum).
Flowers in Araceae may be 2- or 3-merous. In
perigoniate flowers the tepals, when free, are organized in two whorls. The tepals are usually
more-or-less fleshy and fornicate apically (except subfamily Pothoideae) and in some genera or sections
(Anadendrum, Holochlamys, Pedicellarum,
Spathiphyllum sect. Massowia, Stylochaeton) they are
fused into a cup-like structure. Stamens in perigoniate
flowers and in the naked bisexual flowers of most
Monsteroideae have essentially the orthodox structure
of distinct (usually flattened) filament, basifixed anther
and slender, inconspicuous connective. In the unisexual flowers of many tribes of subfamily Aroideae,
however, filaments are typically very short or lacking,
and there is a thick, fleshy connective which probably
acts as an osmophore (Aglaonemateae, Culcasieae,
Homalomeneae, Montrichardieae, Nephthytideae,
Philodendreae, Zantedeschieae). Stamens of tribes
Anubiadeae, Caladieae, Colocasieae, Dieffenbachieae,
and Peltandreae are essentially similar but are always
fused into synandria. In tribe Arophyteae the stamens
may be fused or not and exhibit a diversity of structure. Large connectives also occur in tribe
Spathicarpeae but their different morphology suggests
that they are not homologous with those of the other
26
THE GENERA OF ARACEAE
tribes of subfamily Aroideae mentioned above. Anthers
are almost always extrorse (introrse in Zamioculcas,
latrorse in Pedicellarum). Theca dehiscence may be by
a longitudinal or rarely transversal slit (most genera
with bisexual flowers and some unisexual-flowered
genera: Anubias, some Areae, Arisaema, Arisarum,
Stylochaeton) or by apical or subapical pores or short
slits. In many genera of subfamily Aroideae dehiscence
of each theca is by a subapical stomial pore and this
morphology is frequently correlated with the extrusion
of pollen in strands. Similar structures occur in
Amorphophallus and Dracunculus.
The gynoecium usually varies between 1- and 3locular, and when unilocular often shows traces of 2or 3-merous origin through the presence of a severallobed stigma (e.g. Typhonodorum) or more than one
placenta (e.g. Schismatoglottis). Gynoecia with more
than 3 locules are less common but are found in tribe
Spathicarpeae (1–8 locular) and in Philodendron (2–47
locular). Placentation varies from axile to parietal,
basal, apical or basal and apical (the latter in
Dracunculus, Helicodiceros, Heteroaridarum and
Theriophonum), with many intermediates. Ovules may
be anatropous, campylotropous, orthotropous or intermediate between these types. Funicle trichomes are
usually present (French 1987c) and secrete a clear,
mucilaginous substance which in many genera (e.g.
tribe Monstereae, Philodendron) entirely fills the ovary
locules; this secretion appears to play a role in pollen
tube growth (Buzgó 1994). The style may be narrowed
and elongated (e.g. Dracontium) but in most genera
is relatively inconspicuous externally. However, there
is very often a thick stylar region between the ovary
locules and stigma (e.g. Philodendron, Mayo 1989b).
In tribe Monstereae this stylar region is especially well
developed and densely filled with trichosclereids. Here
the style seems to substitute functionally for a perianth
in protecting the sexual organs of the flower. Stigmas
are always wet in Araceae and in some genera
(Anthurium, Arum, several Lasioideae) produce conspicuous nectar droplets at anthesis. In
Amorphophallus, Dieffenbachia and some
Spathicarpeae, the lobing of the stigma can be very
pronounced, or the stigma relatively massive. In subfamily Monsteroideae stigmas vary from subcapitate
to conspicuously elongated, either transversely (e.g.
Anadendrum) or longitudinally.
C
1-22 Section A Acro 18/7/97 8:02 Page 27
C
5
I N F L O R E S C E N C E A N D F L O R A L A N ATO M Y
Inflorescence and flower anatomy of Araceae
received little attention after the completion of Engler’s
last monograph (Engler 1920b) until very recently.
Knoll (1926) made a detailed study of inflorescence
anatomy in Arum with particular reference to structures and adaptations concerned with pollinator
behaviour. Pohl (1932a, b) and Mayo (1986b, 1989b)
studied inflorescence and floral anatomy in Philodendron and demonstrated the existence of spathe
tissues adapted for opening and closing movements,
resin secretion of various types from resin canals in the
spathe and spadix and a wide variety of gynoecial
and androecial structures. Eyde, Nicolson & Sherwin
(1967) made the first general survey with a study of the
flowers of 18 genera (including Acorus), which concentrated more on those with bisexual or
bisexual-tepalate flowers. They established that in floral anatomy, as in other characters (Grayum 1987),
Acorus differs markedly from the Araceae and confirmed the absence of floral bracts subtending the
flowers. Barabé and coworkers (Barabé1982, 1987;
Barabé & Chrétien 1985, 1986a, b; Barabé, Chrétien &
Forget 1986; Barabé & Forget 1987, 1988a, b, 1993;
Barabé, Forget & Chrétien 1986, 1987; Barabé &
Labrecque 1983, 1984, 1985; Barabé, Labrecque &
Chrétien 1984) have made a series of detailed floral
anatomical studies of different genera with particular
emphasis on floral vasculature. One aim of their studies has been to establish whether unilocular gynoecia
in Araceae are always pseudomonomerous (see also
Eckardt 1937) or if truly 1-carpellate gynoecia occur;
thus far no examples of the latter have emerged.
French (1985a,b, 1986 a,b, c, 1987c) has made familywide surveys of endothecial thickenings, stamen and
ovule vasculature and ovular trichomes. These have
further confirmed the distinctness of Acorus and
revealed some taxonomically useful character variation
within the family. Carvell (1989a, b) has made a
detailed survey of floral anatomy in the bisexual and
bisexual-tepalate flowered genera.
Vogel (1963, 1978) made many fascinating observations, including histological studies, of the terminal
appendix in various genera (Alocasia, Arisaema, Arum
and others) and the spathe limb of Cryptocoryne, in
relation to their biological function as osmophores.
Eyde et al. (1967), Vogel (1963, 1990), Mayo (1986b,
1989b) and Chauhan (unpublished results) demonstrated the existence of papillate and sculptured cell
surfaces in the epidermis of the spathe, androecia and
gynoecia of Amorphophallus, Homalomena, and
Philodendron species; this feature is probably very
widespread in the family. Ittenbach (1993) has made a
very interesting study of the anatomy and micromorphology of some African Amorphophallus species.
I N F L O R E S C E N C E A N D F L O R A L A N ATO M Y
27
1-22 Section A Acro 18/7/97 8:02 Page 28
6
C
FRUITS AND SEEDS
The fruits of Araceae are typically juicy berries,
although rarely drier and leathery. The infructescence
is usually cylindric or sometimes globose. The berries
are most commonly red or orange (see family description) and are almost always free. Exceptions are
Syngonium, in which the berries form an indehiscent
syncarp, and Cryptocoryne which has an apically
dehiscent syncarp. In Lagenandra the berry actively
opens at the base to release the seeds, but aroid berries
are otherwise indehiscent.
The various mechanisms observed for protection of
the developing fruits and seeds have been discussed by
Madison (1979a). In the Monstereae, which have bisexual but non-perigoniate flowers, the thick stylar region
is filled with trichosclereids which protect the developing seeds. At maturity the stylar region is shed to
reveal the seeds. In perigoniate genera like Anthurium
the perigone clearly plays a protective role and keeps
pace during growth of the developing berry. The latter only becomes fully exposed at maturity by extrusion
from the flower. In Lysichiton, also perigoniate, the
stylar region and tepal apices protect the young berry,
eventually breaking off to reveal the ripe seeds (Hultén
& St. John 1931).
In many unisexual-flowered genera the protective
function is assumed by the persistent spathe or spathe
tube. Spathe growth continues around the developing
fruits until maturity when the spathe may split open
(Alocasia, Dieffenbachia) or absciss at the base
(Philodendron), exposing the infructescence of white
or coloured berries. In other monoecious genera, however, the spathe is marcescent and plays no role in
fruit protection. In such cases (e.g. Arum) protection
may possibly be through the presence of toxic chemical compounds in the berries.
The seeds are often embedded in mucilaginous
pulp (secreted by the ovular and placental trichomes).
In Anthurium the inner layer of the pericarp may
also be mucilaginous and in other genera the outer
integument becomes mucilaginous. This makes the
seeds sticky and aids the dispersal of epiphytic and
28
THE GENERA OF ARACEAE
hemiepiphytic species to new sites (e.g. neighbouring
trees) by birds or mammals.
The amount of endosperm in the seed varies considerably within the family and has long been regarded
as a useful taxonomic character at tribal level. However,
a thorough comparative anatomical study has been
lacking until very recently (Seubert 1993). Among a
wealth of other interesting new observations, Seubert’s
study shows that endosperm may be present in mature
seeds of some groups e.g. subfamily Lasioideae, as
only a very thin layer. Many intermediate conditions
exist between the presence of copious endosperm and
absence of endosperm. Absence of endosperm is often
correlated with the presence of a well-developed
plumule and the largest seeds of Araceae are of this
type, e.g. Orontium, Typhonodorum.
The seeds are usually straight, but in Lasioideae
and Monstereae they are often curved, sometimes
strongly so. In a few genera the plumule is also highly
developed (Cryptocoryne, Gonatopus, Nephthytis,
Orontium, Typhonodorum). In Cryptocoryne ciliata,
which grows in freshwater tidal zones, between 20
and 40 cataphylls are formed in the embryo, and these
may serve to fix the seed to the substrate, preventing
it from being swept away with the ebb and flow of
tides. Seeds with a well developed plumule usually
lack endosperm and have only a very thin, papery
testa or none at all (Nephthytis). Such large embryos
generally contain chlorophyll at maturity and are only
viable for a short time.
The testa may be smooth, rough, verrucose or costate,
thin or thick and in subfamily Lasioideae is often very
hard and thick with prominent sculpturing. In tribes
Ambrosineae, Areae, Arisaemateae and Arisareae, most
genera have a prominent fleshy strophiole (aril), and in
tribe Colocasieae smaller but distinct strophioles also
occur. Arillate seeds have been observed in Philodendron
subgen. Meconostigma (Mayo 1986b, 1991). In
Zomicarpa the swollen funicle remains connected to the
mature seed (Peyritsch 1879, Bogner, pers. obs.). In Pistia
a double operculum is formed by both integuments.
1-22 Section A Acro 18/7/97 8:02 Page 29
C
7
SEEDLING MORPHOLOGY
Four different types of seedling can be recognized in
the Araceae (Tillich 1985, 1995, Seubert 1993).
In Type 1, the seeds have copious endosperm, the
cotyledonar hyperphyll functions as a haustorium, the
cotyledonar sheath is condensed and short, the
hypocotyl and primary root are well developed and
first leaf is either a cataphyll or a foliage leaf. This type
is quite common in the family, e.g. Arisaema, Arum,
Calla, Gymnostachys, Pinellia, Zantedeschia.
Type 2 is similar to Type 1, but the cotyledonar
sheath is broadened and blade-like, green and assimilatory, whereas the cotyledonar hyperphyll is a minute
haustorium, e.g. Colocasia, Philodendron, Xanthosoma.
Type 3, which occurs only in Pistia and is very similar to the seedling morphology of Lemna (Lemnaceae),
differs from Types 1 and 2 in that the primary root and
hypocotyl are undeveloped.
In Type 4 the seeds have little or no endosperm.
The cotyledonar hyperphyll functions as a storage
organ and perhaps has a very limited haustorial role
when some endosperm is present. The cotyledonar
sheath, hypocotyl and primary root tend to be reduced
or often completely absent.
In Acorus (Acoraceae) the seedling bears no similarity to any form found in the Araceae. The cotyledonar
hyperphyll is subdivided into a long, cylindrical, assimilatory portion and a small haustorial tip. The first
plumular leaves are unifacial and ensiform and the
primary root is well developed. Tillich (1985, 1995)
has pointed out the resemblance between the seedling
of Acorus and those of the Juncaceae, Melanthiaceae,
and Typhaceae.
In Type 2 and in Acorus, the root collar bears conspicuous, long and densely disposed rhizoids. In Type
1 rhizoids are found only sporadically (e.g. in
Cryptocoryne cognata but not in C. ciliata).
SEEDLING MORPHOLOGY
29
1-22 Section A Acro 18/7/97 8:02 Page 30
8
C
E M B RYO L O G Y
The embryology of Araceae has not been studied on
a broad comparative scale, but excellent reviews have
been published by Grayum (1984, 1991b), on which
this chapter is based. Thorough treatments of all
embryological aspects of a single taxon have been
published for Peltandra virginica (Goldberg 1941),
Theriophonum minutum (Parameswaran 1959) and
Synandrospadix vermitoxicus (Cocucci 1966); other
genera are known less completely. Jüssen (1928) made
the most important single contribution to date, but
generalizations about the family’s embryology are still
based on rather fragmentary coverage.
Acorus (Acoraceae) has a secretory anther tapetum,
thus differing from the Araceae, which have the
periplasmodial type (sensu Clausen 1927). Pollen
mother cell division is probably always of the successive type in Araceae.
The nucellar epidermis of virtually all Araceae divides
to form a nucellar cap, usually 2–3 cell layers thick (1 in
Pistia), and for this reason Araceae have been treated as
30
THE GENERA OF ARACEAE
crassinucellate. However, in a strict sense most Araceae
so far investigated have tenuinucellate ovules, except
Symplocarpus and Calla. An endothelium, derived from
the inner surface of the inner integument, is reported
from most genera investigated. The seed of Acorus has
a perisperm derived from the nucellus in addition to the
endosperm, and in this differs from all Araceae.
Linear megaspore tetrads are the commonest type,
but T-shaped tetrads are also found, sometimes both
types occurring in the same species. The mature
embryo sac is usually of the 8-nucleate type (10–12
nucleate in Nephthytis). Embryogeny is clearly understood in only nine genera. Onagrad and asterad
embryogeny are known in monoecious genera and
caryophyllad and solanad types are known in bisexual
genera. Cellular and free-nuclear types of endosperm
development both occur but after a review of the available facts, Grayum (1984, 1991b) concluded that
endosperm development in Araceae is best interpreted
as a form of the helobial type.
1-22 Section A Acro 18/7/97 8:02 Page 31
C
9
C Y TO L O G Y
This chapter is based on Petersen’s (1989, 1993) recent
comprehensive review of aroid cytology. The 2n chromosome numbers given in Table 1 and in the generic
descriptions are also from her results, supplemented by
unpublished data from Dr. Marcelo Guerra (pers.
comm.). Reliable diploid (2n) numbers and intraspecific
aneuploid derivatives are given, with dubious numbers placed in brackets. The chromosome numbers in
Araceae vary greatly between genera, from 2n=14
(Ulearum) to 2n=168 (Arisaema). Within a single genus
the diploid number may be highly variable, as in
Cryptocoryne (2n=20 to 2n=132), or in Arisaema
(2n=20 to 2n=168). Some genera, on the other hand,
have very stable diploid numbers. Anthurium, the
largest genus of the family, is surprisingly uniform cytologically, with the great majority of species having a
diploid number of 2n=30.
The distribution and variation of chromosome numbers among the genera suggests that chromosome
number has increased in some phyletic lines to a high
level of polyploidy and in others has been greatly
reduced. The most advanced tribes, such as Areae,
Arisaemateae and Cryptocoryneae, tend to have the
highest numbers. In the more primitive genera chromosome number tends to be both less variable and less
extreme, being neither very high nor very low.
Examples of this type are Pothos (2n=24, 36) and
Spathiphyllum (2n=30, 60).
Petersen (1989) considered that no modern Araceae
species constitutes a true primary diploid. In the morphologically most primitive genera the lowest diploid
number is 2n=24. In contrast, the highly derived
Ulearum sagittatum has the lowest diploid number
known in the family (2n=14), evidently the result of
phyletic reduction.
A primary basic number of x=7 has been proposed
by Jones (1957), Larsen (1969) and Marchant (1973).
Petersen (1989) considered that the basic numbers
x=14 or x=12 must have been the starting points for
the derivation of all the modern chromosome numbers in the Araceae. It is possible, however, that these
basic numbers may represent secondary basic numbers which arose by chromosome doubling from
hypothetical basic numbers x=7 or x=6. Petersen
regarded the widely occurring number x=14 as of
ancient origin. She also considered that the number
x=12 might be primitive since the diploid number
2n=24 occurs in tribe Potheae.
Reduction in diploid number occurs in various morphologically advanced genera. A good example is tribe
Areae in which the commonest diploid numbers are
2n=26 and 2n=28 but the genera Biarum and
Typhonium both include species with diploid numbers as low as 2n=16.
Aneuploid changes at the diploid level followed by
polyploidy or aneuploidy at the polyploid level have
taken place in some taxa, e.g. Cryptocoryne ciliata
(2n=22, 33), Cryptocoryne cordata (2n=34, 68, 85, 102).
The size and shape of the chromosomes are also
quite variable. Chromosome length varies from 1–17
µm, depending on the genus. The chromosomes have
been observed to differ greatly in size and shape within
a single genome in certain cases, e.g. the New and
Old World species of Homalomena. Homalomena
speariae (New World) has 42 chromosomes, of which
40 are small (1–2 µm) and one pair is nearly three
times longer (ca. 5 µm). In Old World species there is
no large pair of chromosomes. Chauhan and Brandham
(1985), in a study of Amorphophallus cytology, showed
some appreciable size differences within the karyotypes of certain species.
Ramalho (1994) has made a recent study of Araceae
chromosomes in Pernambuco, Brazil.
C Y TO L O G Y
31
1-22 Section A Acro 18/7/97 8:02 Page 32
Table 1. List of diploid (2n) and assumed basic (x) chromosome numbers in the genera of Araceae.
Chromosome numbers arranged in euploid series are separated by a semicolon; dubious numbers are in
brackets (data from G. Petersen, pers. comm., updated from Petersen 1989 and Guerra, pers. comm.).
2n
x
22, 44; 24, 36, 48
11, 12
I. Subfamily Gymnostachydoideae
1. Gymnostachys
48
12
II. Subfamily Orontioideae
2. Orontium
3. Lysichiton
4. Symplocarpus
26 (24, 28)
28
30, 60 (28)
13
14
15
24, 36
no data
24
12
20, 40; 24, 48, 84; 28, 56; 30, 60, 90
10, 12, 14, 15
30, 60
60
15
15
60
15
28
14
60
60, 120 (42, 54, 56)
60 (56, 84)
60 (42, 56, 58, 64, 70, 112)
60 (24, 48, 56, 58, 70)
84
28, 56
28
15
15
15
15
15
14
14
14
26
26
26
26
26
26
26
26
26
52
13
13
13
13
13
13
13
13
13
13
Family Acoraceae
1. Acorus
Family Araceae
III. Subfamily Pothoideae
Tribe Potheae
5. Pothos
6. Pedicellarum
7. Pothoidium
Tribe Anthurieae
8. Anthurium
IV. Subfamily Monsteroideae
Tribe Spathiphylleae
9. Spathiphyllum
10. Holochlamys
Tribe Anadendreae
11. Anadendrum
Tribe Heteropsideae
12. Heteropsis
Tribe Monstereae
13. Amydrium
14. Rhaphidophora
15. Epipremnum
16. Scindapsus
17. Monstera
18. Alloschemone
19. Rhodospatha
20. Stenospermation
V. Subfamily Lasioideae
21. Dracontium
22. Dracontioides
23. Anaphyllopsis
24. Pycnospatha
25. Anaphyllum
26. Cyrtosperma
27. Lasimorpha
28. Podolasia
29. Lasia
30. Urospatha
32
THE GENERA OF ARACEAE
12
1-22 Section A Acro 18/7/97 8:02 Page 33
VI. Subfamily Calloideae
31. Calla
VII. Subfamily Aroideae
Tribe Zamioculcadeae
32. Zamioculcas
33. Gonatopus
Tribe Stylochaetoneae
34. Stylochaeton
Tribe Dieffenbachieae
35. Dieffenbachia
36. Bognera
Tribe Spathicarpeae
37. Mangonia
38. Taccarum
39. Asterostigma
40. Gorgonidium
41. Synandrospadix
42. Gearum
43. Spathantheum
44. Spathicarpa
Tribe Philodendreae
45. Philodendron
Tribe Homalomeneae
46. Furtadoa
47. Homalomena
Tribe Anubiadeae
48. Anubias
Tribe Schismatoglottideae
49. Schismatoglottis
50. Piptospatha
51. Hottarum
52. Bucephalandra
53. Phymatarum
54. Aridarum
55. Heteroaridarum
Tribe Cryptocoryneae
56. Lagenandra
57. Cryptocoryne
Tribe Zomicarpeae
58. Zomicarpa
59. Zomicarpella
60. Ulearum
61. Filarum
Tribe Caladieae
62. Scaphispatha
63. Caladium
64. Jasarum
65. Xanthosoma
66. Chlorospatha
67. Syngonium
68. Hapaline
Tribe Nephthytideae
69. Nephthytis
70. Anchomanes
71. Pseudohydrosme
36, 54, 72
18
34
34, 68
17
17
28, 56
14
34, 68
34
17
17
no data
34
34
34
34
no data
34
34
17
17
17
17
17
17
28; 30; 32; 34; 36; 48 (26)
15, 16, 17, 18
40
38; 40, 80; 42
20
19, 20, 21
48, 72
24
26, 39, 52
26
26
c. 26
26
24
no data
13
13
13
c. 13
13
12
36, 72
20; 22, 33, 66, 88, 132; 28, 42; 30; 34, 68,
85, 102; 36, 54, 72, 90
18
10, 11, 14, 15, 17, 18
20
26
14
28
10
13
7
7
28
22; 26; 28; 30; 32
22
22; 26, 39, 52
26
28 (24, 26)
26; 28
14
13, 14, 15, 16
11
11, 13
13
14
13, 14
36; 40, 60
40
c. 40
18, 20
20
c. 20
C Y TO L O G Y
33
1-22 Section A Acro 18/7/97 8:02 Page 34
Tribe Aglaonemateae
72. Aglaonema
73. Aglaodorum
Tribe Culcasieae
74. Culcasia
75. Cercestis
Tribe Montrichardieae
76. Montrichardia
Tribe Zantedeschieae
77. Zantedeschia
Tribe Callopsideae
78. Callopsis
Tribe Thomsonieae
79. Amorphophallus
80. Pseudodracontium
Tribe Arophyteae
81. Arophyton
82. Carlephyton
83. Colletogyne
Tribe Peltandreae
84. Peltandra
85. Typhonodorum
Tribe Arisareae
86. Arisarum
Tribe Ambrosineae
87. Ambrosina
Tribe Areae
88. Arum
89. Eminium
90. Dracunculus
91. Helicodiceros
92. Theriophonum
93. Typhonium
94. Sauromatum
95. Lazarum
96. Biarum
Tribe Arisaemateae
97. Pinellia
98. Arisaema
Tribe Colocasieae
99. Ariopsis
100. Protarum
101. Steudnera
102. Remusatia
103. Colocasia
104. Alocasia
Tribe Pistieae
105. Pistia
40, 60, 80, 100, 120 (70, 110)
40
20
20
42, 84
42
21
21
48
24
32
16
36
18
26, 39; 28
26
13, 14
13
38, 76; 54 (40)
54, 108
54
19, 27
27
27
56, 112
112
14
14
28, 42, 56
14
22
11
28, 42, 56, 70, 84
24; 28
28
56
16 (14, 18)
16; 18, 36, 54; 20; 26, 52, 65; >100 (14)
26, 52, 104
c. 78
16; 20; 22; 24; 26; 32; 36; 74; 96; 98*
14
14
14
14
8
8, 9, 10, 13
13
c. 13
?
26, 52
20; 22, 24, 48, 72; 26, 39, 52; 28, 42, 56,
70, 112, 140, 168 (64)
13
28,
28
28,
28,
28,
28,
14
14
14
14
14
14
28
84 (80, 86)
42,
42,
42,
42,
56
56
56
56, 70, 84
10, 11, 12, 13, 14
14
* No attempt has been made in this case to arrange the numbers into euploid series in this genus.
34
THE GENERA OF ARACEAE
C
1-22 Section A Acro 18/7/97 8:02 Page 35
C
10 PA L Y N O L O G Y
Thanikaimoni (1969) and Grayum (1984, 1985, 1992a)
have given detailed comparative surveys of aroid pollen
structure. These studies showed that palynological characters are important for the suprageneric taxonomy.
Aperture type is the feature of most general value.
Bisexual-flowered genera have monosulcate, extensive-sulcate, meridionosulcate (zonate), diaperturate
or forate grains, but monoecious genera have inaperturate grains. The only exceptions seem to be tribe
Spathiphylleae (bisexual, inaperturate), Anadendrum
(bisexual, inaperturate), and tribe Zamioculcadeae
(monoecious, extended-monosulcate to zonate).
Ornamentation may be smooth (psilate), scabrate,
foveolate, reticulate, spinulose, spinulose-reticulate,
spinulose-pilate to papillate, spinose, fossulate, rarely
gemmate, verrucate, retiverrucate, areolate, rugulate
to tuberculate, striate, striate-verrucate, striate-reticulate, striate to plicate or baculate. Spiny pollen grains
are common in Araceae, and have been considered
(Grayum 1984) as an adaptation for aiding attachment
to insect vectors which have hairy bodies. In many
other genera, smooth pollen grains are extruded in
strands composed of many grains glued together by
pollenkitt. These strands also adhere to insect bodies,
sometimes through the aid of sticky secretions within
the inflorescence (e.g. Philodendron). On the basis of
existing observations, smooth pollen is almost always
associated with beetle pollination and spinose pollen
with fly pollination (Grayum 1984, 1985, 1990). Beetles
(Phaeochrous camerunensis, Scarabaeidae-Rutelinae)
and blowflies (Calliphoridae) were both observed as
pollinators in Amorphophallus maculatus which has
almost smooth pollen grains (Bogner 1976a).
The shape is globose to ellipsoid, boat-shaped or
hamburger-shaped (the latter in Gonatopus). The polarity is heteropolar to isopolar or apolar. Usually the
pollen grains are found in monads, only two genera
(Xanthosoma, Chlorospatha) shed the pollen grains in
tetrads, arranged either tetragonally or serially
(Chlorospatha longipoda).
Grain size (measurements given here and in the
generic descriptions are mostly taken from Grayum,
1984, 1992a) varies considerably, from small (12 µm in
Homalomena versteegii) to very large (114 (120) µm in
Pseudohydrosme gabunensis) but the majority of the
genera (68%) are medium-sized (between 25–50 µm
diam., mean 37 µm).
In 73% of species examined the pollen contains
starch although this may vary within a single genus; in
Schismatoglottis some species have starchy pollen and
others do not. Nine out of ten genera with monosulcate
pollen grains were found to be starchless which suggests
that this is the primitive type in Araceae.
PALYNOLOGY
35
1-22 Section A Acro 18/7/97 8:02 Page 36
11 P H Y TO C H E M I S T RY A N D C H E M OTA X O N O M Y
C
by Robert Hegnauer
Several recent reviews have dealt with chemical aspects
of the biology of Araceae (Hegnauer 1963, 1986;
Dahlgren & Clifford 1982; Dahlgren et al. 1985; Bown
1988). Many references to the chemical characters and
the ethnobotany of the family are available in the two
treatments by Hegnauer and in chapters 9 and 10 of
Bown’s book. The present review supplies only the
most essential bibliography, and for additional references the reader should refer to these three sources.
1. Phytochemistry
Mineral deposits and primary metabolites
Oxalic Acid
Aroids produce large amounts of oxalic acid, most
of it being deposited as crystals of calcium oxalate.
Raphide bundles (see also chapter 3), i.e. agglomerations of large, needle-like crystals lying parallel to one
another, are the typical crystal form of the family. These
raphide bundles usually occur singly, embedded in
mucilage within large idioblasts (see section on
Irritants in Araceae). Other types of calcium oxalate
crystals are found in aroids, such as druses, and in
Acorus (Acoraceae), a genus lacking raphides, cells
containing a solitary crystal are situated in rows accompanying fibres. For more detailed studies of calcium
oxalate crystals in Araceae, see Seubert (1993).
According to Molisch (1918), who investigated
Amorphophallus rivieri (= A. konjac), Caladium
nymphaeifolium (probably a variety of Colocasia esculenta), Monstera deliciosa and Sauromatum guttatum
(= S. venosum), aroids also tend to accumulate moderate to large amounts of soluble oxalates in leaves. In
this respect they are similar to Lemnaceae, Helobiae (=
Alismatiflorae) such as Stratiotes aloides and Vallisneria
spiralis, and Zingiberales (Canna, Musa, Maranta).
Silica, aluminium and heavy metals are not known to
be accumulated significantly by members of the family. Tubers of Eminium spiculatum and Arisarum
vulgare were found not to contain soluble oxalic acid;
tartaric and citric acid were detected in both species
(Ahmed et al. 1968).
Carbohydrates
The carbohydrates stored by Araceae have been
investigated many times. Pollard (1982) studied the
36
THE GENERA OF ARACEAE
distribution of kestose- and isokestose-types of sucrose
fructosides in the basal parts of fresh monocotyledonous stems; no such oligofructans (oligofructosans)
were present in Acoraceae (Acorus gramineus) or
Araceae (Arisaema atrorubens (= A. triphyllum),
Dieffenbachia picta (= D. maculata) and Peltandra
virginica were investigated), Lemnaceae, Alismataceae,
Dioscoreaceae, Sparganiaceae and Arecaceae (see e.g.
Dahlgren et al. 1985: 277).
Sakai & Hayashi (1973) studied the distribution of
starchy and sugary leaves in monocots. Japanese
Acoraceae and Araceae belong to those taxa which
temporarily store sugars and non-starchy polysaccharides, but little if any starch, in the leaves. Acorus
gramineus, Amorphophallus konjac, eight species of
Arisaema, Calla palustris, Colocasia esculenta,
Lysichiton camtschatcensis and Pinellia ternata were
investigated. Starch was seen occasionally only in
Acorus gramineus and in two species of Arisaema.
Araceae, which have “sugary leaves” thus differ from
the starchy leaved families Alismataceae,
Dioscoreaceae and Tricyrtidaceae, but resemble most
Japanese members of the Liliiflorae (sensu Dahlgren &
Clifford 1982).
Mucilages
Vegetative parts of the Araceae mainly store starch
(Czaja 1969, 1978a, b; for economically important
Araceae see also Brücher 1977, Mansfeld 1986, Palmer
1989, and for taro – Colocasia esculenta – p. 54 and
table 4.28 in Sunell & Arditti 1983). In some taxa starch
is accompanied by mucilages in considerable amounts,
which usually consist mainly of glucomannans
(Hegnauer 1963, 1986). Ohtsuki (1967) showed that
subterranean parts of most Acoraceae and Araceae
contain much starch but only negligible amounts of
glucomannans (Acorus calamus, Arisaema atrorubens
(= A. triphyllum), A. japonicum (= A. serratum), A. serratum, A. thunbergii, Lysichiton camtschatcensis,
Pinellia ternata, P. tripartita, Amorphophallus campanulatus (= A. paeoniifolius) and A. kiusianus were
investigated). In certain other species of
Amorphophallus starch is partly (A. bulbifer) or largely
(A. konjac, A. oncophyllus, A. variabilis) replaced by
glucomannans, which are located in giant idioblasts. A
procedure to isolate starch-free glucomannans from
tubers of Amorphophallus rivieri (= A. konjac) was
described by Wootton et al. (1993); this glucomannan
had a Gluc : Man ratio of 58 : 42.
Literature concerning mucilages of Araceae is partly
contradictory (Ahmed et al. 1968; Sunell & Arditti 1983:
1-22 Section A Acro 18/7/97 8:02 Page 37
54–55). This is not surprising since mucilages are complex mixtures of heteropolysaccharides and very
difficult to obtain in pure form. Crude mucilages are
always mixed with variable amounts of proteins and
pectic and other substances (see section on Pectins). If
large amounts of mucilage are present in large
idioblasts it is relatively easy to obtain a fairly pure
mucilage, as is the case with the glucomannans of
some species of Amorphophallus. If the major storage
compound is starch, however, the water-soluble “polysaccharides” will always be of different origin, either as
pectic substances, true mucilages such as those contained in raphide idioblasts, some cell wall
hemicelluloses or non-mucilaginous substances like
proteins. According to Amin (1955) and others (see
Sunell & Arditti 1983), mucilages purified from taro
tubers (in several cultivars) are essentially branched
arabino-galactans with an approximate gal:arab ratio of
8:1 to 11:1; this is perhaps the mucilage of the raphide
idioblasts. The mucilages isolated in 3–4% yields from
tubers of Eminium spiculatum and Arisarum vulgare
by Ahmed et al. (1968) were mixtures of pectic substances, hemicelluloses and true mucilages.
Starch grain morphology
Czaja (1969, 1978a, b) investigated rhizomes,
tubers, corms, stems and seeds of many araceous taxa
for the presence and structure of starch grains and
observed two main types: large grains of the so-called
envelope-layer type (Hüllen-Lage-Stärkekörner) and
small granules which are aggregated in compound
grains. Two main subtypes of compound grains were
distinguished by Czaja: highly compound grains
(hochzusammengesetzte Stärkekörner, Czaja 1969:
37–38), composed of 400 and more small granules,
and compound grains (höher zusammengesetzte
Stärkekörner, Czaja 1969: 34–37) with usually up to 10
granules having a diameter of more than 6µm; these
latter granules usually belong to the envelope type
(Hüllen-Stärkekörner). Highly compound grains were
observed by Czaja (1978a) in all araceous seeds; 54
species from 17 genera were investigated. Rhizomes,
tubers and stems are less homogenous (90 species
from nearly 40 genera were investigated). Some store
large grains and some store compound grains. Czaja’s
statements (1969: 36–38, 1978a: 60) concerning the
two subtypes of compound grains mentioned above
are sometimes discordant (e.g. Anthurium, Colocasia,
Pinellia). On consulting the author’s table 1 (description of starch grains) and the figures of starches of
Amorphophallus campanulatus (= A. paeoniifolius),
A. oncophyllus and A. variabilis given in Ohtsuki’s
(1967) paper, it becomes clear that Czaja’s two subtypes of compound starch grains often merge into
one another. The highly compound type in pure form
is probably less frequent in vegetative parts of
Araceae than is suggested by Czaja’s list (1978a,b). For
other detailed studies of starch types in Araceae, see
Seubert (1993).
Pectins
The following remarks concern the occurrence of
pectins in non-lignified cell walls. Jarvis et al. (1988)
showed that dicots and part of the monocots have primary walls with more than 150 mg of galacturonans
per gramme of cell wall preparations (high contents).
Grasses and other Commeliniflorae had low (< 50
mg/g) galacturonan contents. Alocasia and Lemna
(Ariflorae) and all investigated Alismatiflorae and
Liliiflorae belonged to the high-content group; some
monocot taxa had intermediate (50–150 mg/g) galacturonan contents (see section on Mucilages).
Secondary metabolites
Saponins, phenolic compounds including
flavonoids, cyanogenic glucosides, the widespread
occurrence of constituents which cause skin irritation
and painfully acrid sensations on mucous membranes
(mouth, throat, eyes) and calcium oxalate raphides
may be considered the key chemical characters of the
family (Hegnauer 1963, 1986; Bown 1988).
Saponins
Saponins are by no means ubiquitous but were
shown to be probably present in a number of taxa.
Hegnauer (1963) stressed the lack of chemical knowledge about araceous saponins; the occurrence of
steroidal sapogenins was and still remains uncertain
(Hegnauer 1986). Nevertheless, the occurrence of
steroidal saponins was mentioned for Montrichardia
and Pinellia (Dahlgren & Clifford 1982) and for Arales
without indicating genera (Dahlgren et al. 1985). This
discrepancy is most probably caused by the fact that
Altman (1954 in Hegnauer 1963) reported
Montrichardia arborescens to be a rich source of
steroidal sapogenins. His analytical method, however,
was unreliable. Haemolytic and foam-producing substances, generally believed to be saponins, were shown
to be present in many species (Clark & Waters 1934,
Fontan-Candela 1957, Hegnauer 1963, Schroeter et al.
1966), but authors screening for steroidal saponins
(Villar Palasi 1948, Anzaldo et al. 1957, Wall et al.
1954–1961) never obtained indications for this type of
saponin nor could they detect or isolate steroidal
sapogenins after hydrolysis (Marker et al. 1947, Wall et
al. 1954–1961). According to Villar Palasi (1948),
saponins are probably present in some parts of Alocasia
odora and Arum italicum, according to Anzaldo et al.
(1957) in Acorus calamus (Acoraceae), Amorphophallus
campanulatus (= A. paeoniifolius) and Colocasia esculenta, and according to Wall et al. (1954–1961) in Acorus
calamus (Acoraceae), several taxa of Colocasia, a
species of Philodendron and Symplocarpus foetidus
(confirmed by Segelman & Farnsworth 1969). All these
researchers failed to detect saponin-like substances in
P H Y TO C H E M I S T RY A N D C H E M OTA X O N O M Y
37
1-22 Section A Acro 18/7/97 8:02 Page 38
the investigated plant parts of Arisaema triphyllum,
Arisarum vulgare, Amorphophallus bulbifer, several
taxa of Colocasia, Dieffenbachia cordata, Dracunculus
canariensis, Monstera deliciosa, Montrichardia
arborescens, Orontium aquaticum, Peltandra virginica,
Pistia stratiotes and Zantedeschia aethiopica. No
appreciable amounts of saponins were present in
Anchomanes difformis or Cyrtosperma senegalense (=
Lasimorpha senegalensis) (Delaude-Hulst 1974), or
Typhonium brownii (Simes et al. 1959). Summarizing,
it may be stated that saponin-like substances occur
occasionally in Araceae but that the chemistry of the
saponins is still totally unknown.
Phenolic compounds
Phenolic compounds occur in large amounts and are
structurally and biosynthetically diverse. Bate-Smith
(1968) investigated hydrolysed leaf extracts of 24 araceous plants. Ten of them contained procyanidins
(formerly leucocyanidins), seven contained quercetin,
six kaempferol, ten caffeic acid, seventeen p-coumaric
acid, twelve sinapic acid and eleven contained ferulic
acid; in the case of Orontium aquaticum the presence
of scopoletin was indicated. A much more comprehensive survey of proanthocyanidins, cinnamic acids,
anthocyanins and flavonoids of Araceae was published
by Williams et al. (1981). According to these investigators, procyanidins occur in leaves of nearly half the
investigated taxa and C-glycoflavones are the characteristic leaf flavonoids of the family. In some taxa they are
accompanied or even replaced by O-glycosides of
flavonols or flavones. Sulphates (esters of sulphuric acid)
of vitexin, isovitexin, vitexin 7-glucoside, chrysoeriolgalactoside and quercetin occur sporadically
(Philodendron ornatum, Culcasia saxatilis, Scindapsus
pictus). As yet not fully characterized sulphates of esters
of caffeic acid (sulphated caffeoyl glucoses?) are much
more common, being mainly present in subfamilies
Monsteroideae (67%), Philodendroideae (23%) and
Pothoideae (20%); non-sulphated caffeic acid derivatives
with a free carboxylic group are common in subfamilies
Colocasioideae (80%), Lasioideae (38%) and Pothoideae
(20%) (subfamily circumscriptions in Williams et al. 1981
follow Bogner 1979a). The results of this investigation
have been summarized twice by the authors (Harborne
1982; Williams & Harborne 1988). It is highly probable
that the two types of acidic caffeic acid derivatives
detected by Williams et al. (1981) are involved in the irritating properties distinguishing most aroids (see Irritants
in Araceae). Ellis et al. (1983) showed that the chemistry
of the proanthocyanidins of the fruits of Zantedeschia
aethiopica (two types investigated) and Z. rehmannii
varies with the taxon. They contain afzelechin, catechin
and (or) gallocatechin and their epimers as building
blocks and consist either of pure procyanidins, mixtures
of propelargonidins and procyanidins or mixtures of
prodelphinidins and procyanidins. Since p-coumaric acid
38
THE GENERA OF ARACEAE
and ferulic acid are common in the family it is worth
mentioning that they never seem to be bound to the
cell wall polysaccharides. Harris & Hartley (1980) showed
that p-coumaric, ferulic and diferulic acids occur combined with non-lignified cell walls in all investigated
members of Commelinidae (sensu Cronquist 1981) and
in Arecaceae, Philydraceae, Pontederiaceae and
Haemodoraceae in the strict sense. Araceae (Arum
italicum, Pistia stratiotes and Sauromatum venosum have
been investigated) and Acoraceae (Acorus calamus), like
Alismatidae and typical Liliidae, lack this character.
Acorus calamus has p-hydroxybenzoic acid combined
with non-lignified cell walls; this feature occurs erratically
in vascular plants. Phenolic amines are dealt with in the
section on Biogenic amines and alkaloids.
Recapitulating, it may be said that proanthocyanidins and C-glycoflavones and derivatives of caffeic acid
belong to the main phenolics of the family, but that glycoflavones may be replaced in certain taxa or
populations by flavonol glycosides (Stylochaeton; rutin
in middle European Arum maculatum; kaempferol
3,7-bisglycoside in Gymnostachys anceps) or flavoneO-glycosides (tribe Areae sensu Bogner 1979a) as main
leaf flavonoids (Williams et al. 1981, Hegnauer 1986,
Williams & Harborne 1988). Leaves of Eminium spiculatum yielded the C-glycoflavones vitexin, isovitexin
and its 7-glucoside (= saponarin), iso-orientin and its
7-galactoside, vicenin-1, the flavone-O-glycosides luteolin 3’-glucoside, luteolin 7-glucoside and chrysoeriol
7-glucoside and the flavanone glycoside eriodictyol 7glucoside (Shammas & Couladi 1988).
A second lignanoid compound (see also acoradin,
in Essential oils), a 1-ethyl-2-methyl-3-aryl-indane
derivative, was isolated from rhizomes of Acorus calamus (Saxena 1986); it seems to arise by spontaneous
dimerisation of asarone (Al-Farhan et al. 1992). A series
of glucosylated lignans was recently isolated from subterranean parts of Arum italicum, together with ferulic
acid and glycosides of coniferyl alcohol and 4coumaryl alcohol (Della Greca et al. 1993). Whole
plants yielded traces of 8-O-3’ and 8-O-4’ neolignans
(Della Greca et al. 1994; see also Gellerstedt et al.
1995). Inflorescences of Zantedeschia aethiopica
yielded the C-glycoflavones swertisin and swertiajaponin (Sivakumar & Nair 1992).
Cyanogenic glucosides
Cyanogenic glucosides have been known since the
work of Jorissen, Greshoff and Treub (see Hegnauer
1963, 1977, 1986) to be rather common in the family.
The distribution and chemistry of cyanogenesis (the
ability to release HCN after injury) in aroids have been
thoroughly discussed by Hegnauer (1963, 1973, 1977,
1986). Additional observations have been published
by McBarron (1972: one of three tested samples of
Gymnostachys anceps was weakly and two were
strongly cyanogenic), Kaplan et al. (1983: two out of
1-22 Section A Acro 18/7/97 8:02 Page 39
O Gluc
NH 2
HOOC
HOOC
COOH
HO
CN
II
1
I
C
CO2
O Gluc
OH
NH 2
COOH
COOH
HO
VII
OH
+ 12_ O2
O
V
2
N
O
OH
IV
CH3 COOH
VI
O
HO
NH 2
NH 2
HO
III
HO
IX
RO
3
RO
4
1
COOH
HO
CO2
VIII
CHO
OH
1
XII
8’
HO
Y
3
14’
5
1’
XIV
COOH
17’
Me
11’
HO
Y
XI
B- ring
OH
R
O
8
7
1
B
O
A
PA L
Gluc
6
A-ring
OH
O
XV
NH 2
s everal ty pes
of amid es
COOH
CH3 COOH
or
CH2
HOOC
COOH
XIII
X
Figure 8. Some general lines of secondary metabolism of Araceae and some of their key chemical characters
I-IX = Tyrosine and some of its metabolites: I = Tyrosine; II = cyanogenic glucoside Triglochinin; III = oxoaporphine Liriodenine; IV and V =
Homogentisic acid and its 2-glucoside which are responsible for the so-called egumi-taste according to Hasegawa et al. (1959); VI = Acetic acid
generated by total catabolism of tyrosine; VII = Tyramine; VIII = DOPA; IX = Dopamine, one of the possible causes of melanogenesis in dying
parts of araceous plants; X-XII = presumably metabolites of phenylalanine:– X = Phenylalanine; XI = p-Coumaric (Y = H), Caffeic (Y = H, OH),
Ferulic (Y = H, OMe) and Sinapic (Y = OMe) acids; XII = 3,4-Dihydroxybenzaldehyde (R=H) and its diglucoside, 3,4-Diglucosyloxybenzaldehyde
(R = Glucosyl), which are responsible, at least partially, for “Hange” and “Taro” acridity according to Suzuki et al. (1975); XIII and XIV = pure
Acetogenins:– XIII = Acetic or Malonic acids (activated forms); XIV = main allergen of Philodendron, 5-Heptadec-8’,11’,14’-trienylresorcinol; XV
= the 6-C-glucoflavones Isovitexin (= Saponaretin: R = H) and Saponarin (R = Glucosyl); flavonoids are of mixed biogenetic origin.
1 and 2 = enzymes of tyrosine catabolism; 2 = “Homogentisicase” of Hasegawa et al. (1959).
PAL = Phenylalanine lyase
➤ = alternative pathways indicated.
P H Y TO C H E M I S T RY A N D C H E M OTA X O N O M Y
39
1-22 Section A Acro 18/7/97 8:02 Page 40
four tested samples of an Anthurium species and four
out of six samples of Philodendron corcovadense were
cyanogenic) and Gibbs (1974: cyanogenesis was
demonstrated for Anthurium aemulum, A. scandens,
Calla palustris). I could not confirm the latter for a
Dutch sample of this species, Schismatoglottis sp. (“S.
ruttenii”), Xanthosoma lindenii (= Caladium lindenii)
or Zantedeschia rehmannii. In the case of Gibbs
(1974), only personal observations are taken into consideration because of his rather uncritical evaluation of
results published by other investigators; he accepted
without comment many highly doubtful cases of
cyanogenesis reported in the literature.
Triglochinin, a seco-derivative of dhurrin or taxiphyllin, is the cyanogenic glucoside occurring in all
Araceae so far investigated for cyanogenesis. It is
accompanied by a substrate-specific enzyme (“triglochininase”) which rapidly splits the glucoside after
injury. Cyanogenesis is therefore often extremely rapid
in Araceae and in many instances the HCN is totally
lost during the drying of plant parts. Triglochinin and
the corresponding enzyme were shown to be the
cause of cyanogenesis in Alocasia macrorrhizos (tribe
Colocasieae), Arum maculatum (tribe Areae), Pinellia
tripartita (tribe Arisaemateae), Lasia spinosa (subfamily Lasioideae) and Dieffenbachia picta (= D.
maculata, tribe Dieffenbachieae) by Nahrstedt and his
group (see Hegnauer 1986).
Polyhydroxy alkaloids or alkaloidal
glycosidase inhibitors (AGIs)
This class of biologically active secondary metabolites has been shown in recent years to comprise the
toxic principles of Locoweeds (Astragalus, Oxytropis),
Darling Peas (Swainsona) and Moreton Bay Chestnut
or Black Bean (Castanospermum australe), all belonging to the Leguminosae. The same and similar
compounds occur also in some fungi, a fern, several
Euphorbiaceae, Moraceae and Polygonaceae, but had
not been reported previously from monocotyledonous
plants. A research group at Kew (Sharp et al. 1993) has
been screening Araceae for this type of metabolite. So
far about 70 species from 47 genera have been investigated, and appreciable amounts of AGIs were
detected in leaves of several genera of subfamily
Aroideae:
Anchomanes,
Nephthytis
and
Pseudohydrosme (tribe Nephthytideae) and Aglaonema
and Aglaodorum (tribe Aglaonemateae). Trace amounts
of AGIs were present in species of Amorphophallus
(tribe Thomsonieae). Accumulation of AGIs thus
appears to support the present circumscription of
Nephthytideae and Aglaonemateae. The major araceous
AGIs were identified as DMDP, a 2,5-dihydroxymethyl3,4-dihydroxypyrrolidine, an N-analogon of
fructofuranose and two piperidine derivatives, HNJ
(2,6-dihydroxymethyl-3,4,5-trihydroxypiperidine) and
DMJ (= deoxymannojirimycine). Several minor com-
40
THE GENERA OF ARACEAE
pounds still await definitive identification. It is rather
unexpected that no new AGIs were detected in
Araceae; their three main polyhydroxy alkaloids had
formerly been isolated from other taxa, e.g.
Leguminosae and Euphorbiaceae. Obviously the synthesis of such sugar- and/or pipecolic acid-related
compounds is a common feature of a large number of
plants and microorganisms, but their accumulation is of
much more restricted occurrence.
Irritants in Araceae
Peckolt (1893; see Hegnauer 1963) reported long
ago that several types of irritants must occur in Brazilian
Araceae. A comprehensive summary of irritant aroids
and their irritating properties is given by Mitchell &
Rook (1979); see also Hegnauer (1963, 1986), and Bown
(1988). Brazilian scientists have paid much attention to
the irritating and toxic properties of Araceae. Lethal
intoxications of children from eating the spathe and
spadix of cultivated Zantedeschia aethiopica have been
reported (Ladeira et al. 1975). Working with juices
expressed from different parts of Dieffenbachia picta (=
D. maculata) it could be demonstrated that stems and
petioles are much more aggressive than leaf blades and
the centrifugation of the stem and petiole juices resulted
in an inoffensive supernatant and a highly offensive
precipitate. Moreover, it was shown that the toxic principle(s) of this species is (are) not of proteinaceous
nature and neither stable to prolonged heating nor to
vacuum drying (Ladeira et al. 1975; see also Carneiro
1985). Later these observations were confirmed and
raphides present in the precipitates were investigated;
they lost their irritating and toxic properties on washing
with ether, but not on washing with water (Jesus Neves
et al. 1988). Dieffenbachia maculata contains an
inhibitor of human salivary amylase and several other
types of amylases (Padmanabhan & Shastri 1990). It is,
however, improbable that such inhibitors are involved
in Dieffenbachia toxicity.
Contact dermatitis
Contact dermatitis is caused by some species of
Philodendron. Their main allergens have been isolated and identified as alkenylresorcinols with one,
two or three double bonds; they are accompanied by
corresponding tridecyl-, pentadecyl- and heptadecylresorcinols. Philodendron scandens subsp.
oxycardium is the most noxious taxon investigated
hitherto and may contain much 5-pentadecatrienylresorcinol. Philodendron angustisectum, P. erubescens
and P. radiatum are also suspected of being able to
cause contact dermatitis because mono- and di-unsaturated alkenylresorcinols have been detected in them.
On the other hand, no alkyl- nor alkenylresorcinols
were observed in P. bipennifolium, P. fenzlii, P. sagittifolium, P. squamiferum or P. tuxtlanum (Reffstrup et
al. 1982, Reffstrup & Boll 1985).
1-22 Section A Acro 18/7/97 8:02 Page 41
Non-allergenic skin irritations
Non-allergenic skin irritations can occur in persons
handling large quantities of horticultural Araceae. They
may be caused by the combination of raphides and
papain-like proteolytic enzymes like the so-called
dumbcain described for taxa of Dieffenbachia. This
type of skin lesion is best known from workers in the
pineapple industry (Ananas comosus, Bromeliaceae).
metabolite of tyrosine, and its 2-glucoside were shown
to be responsible for this taste sensation. It should not
be forgotten, however, that large amounts of soluble
oxalates as well as certain proanthocyanidins can also
produce taste sensations of a tart to slightly bitter,
astringent or acrid nature. Moreover, egumi-taste gradually passes into taro acridity (Hasegawa et al. 1959).
Irritation of mucous membranes
Painful irritations of mucous membranes are caused
by many araceous plants. Long ago, Chauliaguet (1897;
see Hegnauer 1963) showed that raphides alone are
harmless. Notwithstanding this fact, raphides are still
believed to be the main irritating factor of Araceae by
many modern authors who are not familiar with the
pertinent literature. Raphides, however, are only the
vehicles of irritating substances. The construction and
contents of araceous raphide idioblasts (Wiley 1903;
Safford 1905; Middendorf 1983; Tang & Sakai 1983)
and the structure of the individual needles (Sakai et al.
1972; Tang & Sakai 1983) suggest that they are adapted
to transport acrid, pain-producing and otherwise irritating substances. According to Suzuki (1969, 1975),
3,4-dihydroxybenzaldehyde (protocatechualdehyde)
and its 3,4-bisglucoside are acrid constituents of tubers
of Pinellia ternata and Colocasia antiquorum (= C.
esculenta). Presumably the sulphated and acidic derivatives of caffeic acid mentioned earlier also take part
in araceous acridity.
It is still uncertain whether specific pain-producing
substances are also involved in painful irritations of
mucous membranes caused by Araceae. Pain-producing
oligopeptides like moroidin of Laportea moroides in the
Urticaceae (Leung et al. 1986) may be part of the “dart”
poison of some Araceae. Saponins may also be involved
in the acridity of aroid species which produce and store
these substances; it is known that several saponins (formerly called sapotoxins) are highly irritating to mucous
membranes. According to Tang & Sakai (1983), Suzuki’s
(1969, 1975) diglucosyloxybenzaldehyde was a misidentification; they assumed that in fact the isolated
compound was 5-(hydroxymethyl)-furfural, a decomposition product of some hexoses under acidic
conditions. Notwithstanding the fact that the reports of
Suzuki (1969) and Suzuki et al. (1975) contain inaccuracies, it is clear that Tang & Sakai failed to read carefully
Suzuki’s (1969) paper and it is highly improbable that
their acrid bisglucoside C19H26O13, was a derivative of 5(hydroxymethyl)-furfural.
Biogenic amines and alkaloids
Egumi taste
Another effect of Araceae on mucous membranes
was described by Hasegawa et al. (1959) for dried
tubers of Pinellia ternata (“Hange”). They have a
harsh, somewhat bitter and astringent taste similar to
the so-called egumi-taste of edible shoots of some cultivars of Phyllostachys edulis (Gramineae subfamily
Bambusoideae). In both cases homogentisic acid, a
Biogenic amines and alkaloids occur in many
Araceae. True alkaloids seem to be rare but perhaps
rather significant from the taxonomic standpoint
because they indicate biochemical relationships with
Magnoliidae. The aporphine-type alkaloids liriodenine
and lysicamine were isolated from roots of Lysichiton
camtschatcensis. Tubers of Pinellia ternata yielded
ephedrine. A tertiary base, C20H35O2N, was isolated
from tubers of Eminium spiculatum (Ahmed et al.
1968). Traces of volatile biogenic amines, but no coniine, were shown to be present in tubers and leaves of
Arisarum vulgare, Arum maculatum (here also traces
of nicotine were present) and Eminium spiculatum.
Just before and during flowering, spadices and
spathes of a number of Araceae produce large amounts
of volatile amines and indoles, giving them a putrescent
odour attractive to their pollinators. The composition of
these “perfumes”, which may even contain skatol, is
taxon-dependent (Hegnauer 1986; Bown 1988). The
temperature of the upper part of the spadix rises
considerably just before anthesis; this increases volatilization of amines. The substance triggering heat production
in the spadix is known as “calorigen” and was shown
recently to be salicylic acid in Sauromatum guttatum (=
S. venosum) by Raskin et al. (1987). Spathes and male
and female flowers of many Araceae also produce large
amounts of non-volatile amides of p-coumaric and ferulic acids with putrescine, spermidine, tyramine and, in
Zantedeschia aethiopica, spermine. Large amounts of
free tyramine and (or) dopamine were present in these
parts of Monstera deliciosa, Philodendron andreanum
(= P. melanochrysum), P. erubescens, P. martianum, P.
scandens, P. selloum (= P. bipinnatifidum), P. tripartitum, Remusatia vivipara, Rhaphidophora decursiva and
Zantedeschia aethiopica, but not in Arisarum vulgare,
Arum maculatum, A. italicum, or Dracunculus vulgaris.
Up to 4 mg dopamine/g fr. wt were observed in one
month-old ovaries of Monstera deliciosa (Ponchet et al.
1982). The tendency for spathes and other plant parts to
turn black (melanogenesis) in a number of Araceae may
be due to the simultaneous presence of dopamine and
phenol oxidases.
The starch-rich tubers of North African and
Mediterranean Arisarum vulgare are known in
Morocco as “Irni” or “Erni”. This name is used, however, for several taxa of subfamily Aroideae with
starch-rich edible tubers which also contain toxins, and
are suitable as food only after adequate treatments
P H Y TO C H E M I S T RY A N D C H E M OTA X O N O M Y
41
1-22 Section A Acro 18/7/97 8:02 Page 42
such as heating and drying or repeated cooking etc.
(Bellakhdar 1978). A pyrrolidine alkaloid called irniine,
C20H33N, was isolated from tubers of Arisarum vulgare
and shown to be one of the toxic principles of this
species (Melhaoui et al. 1992).
Miscellaneous compounds
Essential oils
Acorus (Acoraceae), with two species, A. calamus
and A. gramineus, is a highly aromatic taxon. The roots,
rhizomes and leaves produce large amounts of essential oils, which are stored in idioblasts similar to the oil
cells of woody polycarps (Magnolianae sensu Takhtajan
1959), aromatic Gramineae and Zingiberaceae. Both
species of Acorus comprise several chemodemes with
respect to the composition of essential oils. Best known
are the taxa which produce the biologically active
phenylpropanoid cis-asarone (= ß-asarone), which has
insecticidal and antifeedant properties (Koul et al. 1990).
This compound occurs together with the less toxic
trans-asarone, mainly in triploid European A. calamus
and in much larger quantities in Indian tetraploids
(Hegnauer 1963, 1986; Röst 1979b). Rhizomes of Indian
A. calamus also contain the dimethylbutanoid lignan
acoradin (a dimer of cis-asarone, see Saxena &
Mukherjee 1985), as well as asar(yl)aldehyde, acoramone, and galangin; for mono- and sesquiterpenoid
constituents of Acorus oils, the reader is referred to
Röst (1979b), Röst & Bos (1979) and Hegnauer (1986).
Stereoisomers of acoradin are andamanicin from Piper
sumatranum var. andamanicum, heterotropan from
Asarum taxa and magnosalin from Magnolia taxa
(Malhotra et al. 1990). A chemotype of Acorus
gramineus cultivated in Italy accumulates a number of
phenylpropanoids, including ß-asarone and its epoxide,
which suppress growth of several microalgae (Della
Greca et al. 1989).
Another aromatic genus of Araceae is Homalomena
(Wealth of India 1959; Bown 1988: 223). H. aromatica
yielded 1.2% essential oil containing mainly monoterpenoids (Hegnauer 1986). Rhizomes of Homalomena
aromatica contain an essential oil with up to 80% of
linalool and several sesquiterpenoids of which the
homalomenols C and D are new compounds with the
rather rare carbon skeleton of mintsulphide and the
aphanomols (Sung et al. 1992). Rhizomes of
Homalomena occulta, a Chinese medicinal crude drug,
yielded 0.79% of essential oil with much linalool and
lesser amounts of other monoterpenoids and sesquiterpenoids (Zhou et al. 1991). Pistia stratiotes produces
similar allelochemicals, one of which was shown to be
asarone (Aliotta et al. 1991). Peltandra virginica is pollinated by the chloropid fly Elachiptera formosa, which
also breeds in the inflorescences of this plant. This
peculiar symbiosis between a plant species and its pollinating insect seems to depend, at least in part, on
42
THE GENERA OF ARACEAE
odoriferous compounds, which are synthesized by
spathes and spadices of Peltandra and which function as a lure for the pollinator (Patt et al. 1992).
Notwithstanding the toxicity of asarone to many
insects, it seems to have become, together with other
volatile phenylpropanoids, asarylaldehyde and the
sesquiterpenoid acarogermacrone, a trigger for certain
behavioural activities of fruit flies of the genera Ceratitis
and Dacus (Jacobson et al. 1976). Larvae of fruit flies
are often serious orchard pests and substances attracting males and (or) females may become useful as lures
for capturing adults of pest-causing insects. An example of such a use is Spathiphyllum cannifolium, which
is planted in Northern Thailand around orchards. Its
flowering inflorescences do not emanate foetid amines,
but a mixture of benzyl acetate, methyleugenol,
methylchavicol, p-methoxybenzaldehyde, propyltetradecanate and yet other compounds, which are highly
attractive to several species of fruit flies; Lewis et al.
(1988) report the same attraction for the fruit fly Dacus
musae in Northern Queensland.
Another fascinating observation was published by
Seidel et al. (1990) as follows. Anthurium gracile, A.
ernestii and Philodendron megalophyllum belong to
the so-called ant garden plants found in lowland
Amazonian Peru. Workers of the ant Camponotus
femoratus collect seeds of these and some other, taxonomically unrelated plants and store them in brood
chambers where they later germinate. Volatile aromatic
compounds may be cues which initiate collection of
the seeds of these epiphytic plants by ants. In the case
of the aroid species, 6-methyl methyl salicylate, benzothiazole and vanillin were detected in seed coats
and adhering fruit parts.
Phytosterols and triterpenes
Sitosterol-type phytosterins are ubiquitous in vascular plants. ß-sitosterol palmitate was isolated from
tubers of Amorphophallus campanulatus (= A.
paeoniifolius) together with other phytosterols, triacontane, lupeol and betulinic acid by Chawla &
Chibber (1976). New di- and trioxigenated sterols
have been isolated from tubers of Colocasia esculenta (Ali 1991) and from Pistia stratiotes (Aliotta et
al. 1991; Monaco & Previtera 1991).
As far as I am aware, there exist only a few other
reports concerning the occurrence of triterpenes in
Araceae. Taraxerol acetate was isolated together with
phytosterins, lignoceric acid, hentriacontane, hentriacontanol and hentriacontanone from rhizomatous
stems of Alocasia fornicata (Sharma et al. 1972).
Air-dried aerial parts of Xanthosoma robustum collected in Oaxaca, Mexico, yielded four antibacterial
hydroperoxy derivatives of 4,14-dimethyl-cholesta-8en-3ß-ol and of cycloartenol (Kato et al. 1996).
1-22 Section A Acro 18/7/97 8:02 Page 43
Epicuticular waxes
Behnke & Barthlott (1983), Fröhlich & Barthlott
(1988) and Barthlott (1990) showed that the presence and architecture of epicuticular waxes is a
character useful for the classification of monocotyledons. Their so-called Strelitzia-type and
Convallaria-type seem to be restricted to monocots
and to characterize major taxa, i.e. either parts of the
Zingiberiflorae, Commeliniflorae, Areciflorae and
Bromeliiflorae, or parts of the Liliiflorae. The
Ariflorae, like the Alismatiflorae, Triuridiflorae and
Dioscoreales (Liliiflorae), lack these characteristic
types of epicuticular waxes (compare Dahlgren et
al. 1985: 65, 96, 98–99).
2. Chemotaxonomy
It is advisable not to put too much weight on
chemical characters with regard to estimating phylogenetic relationships of the Araceae as long as the
chemical structures of araceous saponins remain
unknown. As stated here and in an earlier publication
(Hegnauer 1986), there are similarities between the
primary and secondary metabolism of the Araceae
and a rather large number of other monocotyledonous taxa. The most striking chemical attributes of the
family are metabolites derived from tyrosine (triglochinin and tyramine, dopamine and their amides;
egumi-taste principles (Hasegawa et al. 1959) and the
presumably related, acrid constituents). However, the
participation of tyrosine in the production of secondary metabolites such as the cyanogenic glucosides
dhurrin, taxiphyllin and triglochinin (Hegnauer 1973,
1977, 1986: 356–357) and the amaryllidaceous and
colchicinoid types of alkaloids (Hegnauer 1986: 316,
576), is widely scattered in monocotyledons.
Ultimately, one point cannot be overemphasized.
Use of chemical characters for taxonomic purposes
can only be meaningful if all available facts are
checked and evaluated carefully. Authors who neglect
to exploit information made readily available in handbooks (Wehmer 1929, 1931, 1935; Hegnauer 1963, 1986
(for monocotyledons)) do not do a good job as far as
the chemotaxonomic part of their work is concerned.
Furthermore, the need to consult as many original
papers as possible can be illustrated by two curious
examples. First, the cause of the painful acridity of
most araceous plants is still ascribed solely to the presence of raphides by many authors. Secondly, the
summary in Hegnauer (1986), based on the original
paper, of the results of the phenolic research carried
out by Williams et al. (1981) is actually more accurate
than a summary later given by the authors themselves
(Williams & Harborne 1988).
P H Y TO C H E M I S T RY A N D C H E M OTA X O N O M Y
C
43
1-22 Section A Acro 18/7/97 8:02 Page 44
12 E C O L O G Y A N D L I F E F O R M S
C
Croat (1990, 1992a) has published a more detailed
review of araceous life forms and ecology.
The growth of Araceae is dependent on abundant
available water and prevailing atmospheric humidity.
Structurally and physiologically they are not well
adapted for growth in arid or cold conditions, and hence
do not occur in the most extreme environments.
Araceae are most diverse and abundant in the
humid tropics and it is there that the richest variety of
their life forms is found. Relatively few genera inhabit
temperate regions of the world and these are either
geophytes (e.g. Arisaema, Arum, Pinellia) or helophytes (Calla, Lysichiton, Orontium, Peltandra,
Symplocarpus, ).
The very few genera found at high altitudes exist
in a warm temperate climatic regime and are also
geophytic. Gorgonidium has been found at around
3000m in the Andes, while Arisaema occurs at up to
3000m in Africa (A. ruwenzoricum in the Ruwenzori)
and 4400–4500m in the Himalaya (A. flavum, A.
jacquemontii, A. lobatum).
Taxonomic considerations
From the taxonomic and evolutionary viewpoints
there are some generalizations that can be made concerning life forms. Hemiepiphytes are commonest in
the more primitive tribes and subfamilies. Most genera
of subfamilies Pothoideae and Monsteroideae are
hemiepiphytes and among more advanced genera this
life form occurs only in tribe Culcasieae, Philodendron
and Syngonium, all belonging to subfamily Aroideae.
These latter genera show marked structural adaptations in their habit and in these features must be
considered derived. Aquatic, subaquatic and helophytic
genera are scattered throughout the family from very
primitive groups such as subfamily Orontioideae to
very advanced ones such as tribe Cryptocoryneae and
Pistia in subfamily Aroideae.
The least specialized mesophytic habit is shown by
some rainforest terrestrial herbs. In these the stem is
aerial and erect or decumbent, with short but distinct
green internodes. This habit type has been judged
primitive in the family by some previous authors (e.g.
Grayum 1990), but in fact is found predominantly in
more advanced genera. Typical examples are
Aglaonema (tribe Aglaonemateae), Dieffenbachia (tribe
Dieffenbachieae), Homalomena (tribe Homalomeneae)
and Schismatoglottis (tribe Schismatoglottideae), all of
subfamily Aroideae. Among primitive groups only tribe
Spathiphylleae and terrestrial Anthurium species have
44
THE GENERA OF ARACEAE
this habit. Many other genera, however, seem to represent relatively small adaptive shifts from a mesophytic
norm. Within subfamily Lasioideae for example, Lasia,
Podolasia and many species of Cyrtosperma have
habits which are intermediate between the helophytic/mesophytic and geophytic/mesophytic
categories. Nephthytis, in which the rhizomes normally
grow superficially, has a considerably more mesophytic habit than the strongly tuberous stems of the
other two genera of tribe Nephthytideae. Culcasia has
many terrestrial species, spanning the hemiepiphytic/mesophytic categories, and Philodendron is
similar. Anubias is predominantly helophytic but
Dieffenbachia and Spathiphyllum, while typical of
wetter habitats, also occur on drier ground within a
humid tropical habitat. In the predominantly geophytic
tribes Caladieae and Colocasieae, the genera Alocasia,
Colocasia and Xanthosoma have mesophytic species
with decumbent to erect, arborescent stems, while
Steudnera and Chlorospatha are exclusively of this
type. The most primitive Araceae, subfamilies
Gymnostachydoideae and Orontioideae, are geophytes, rhizomatous helophytes or aquatics, and
largely extratropical. While their habits are doubtless
a prerequisite for survival in a more demanding climate, and therefore could have evolved from a
mesophytic common ancestor, it is nevetherless
equally possible that the mesophytic habit has evolved
various times within the more advanced subfamilies
from geophytic or helophytic ancestors.
The geophytic habit is strongly represented in the
relatively primitive subfamily Lasioideae and particularly
common in the most advanced subfamily Aroideae.
The rheophytic habit is characteristic of tribe
Schismatoglottideae, the genera being almost exclusively rheophytic except for Schismatoglottis, which
consists mainly of terrestrial mesophytic herbs.
Hemiepiphytes
Humid tropical forests are the characteristic habitat of hemiepiphytic genera. The species vary
considerably in size, from shortly climbing plants
found on the major branches or trunks of trees (some
Anthurium species) to huge plants with attached
stems growing high into the forest canopy and producing enormously long, pendent flowering stems
(e.g. Philodendron scandens). Hemiepiphytes can be
divided into primary and secondary hemiepiphytes.
Primary hemiepiphytes begin growth above ground
level but produce feeder roots which eventually grow
1-22 Section A Acro 18/7/97 8:02 Page 45
down to the forest floor. Secondary hemiepiphytes
germinate on the forest floor, grow up tree boles,
become detached from the ground by rotting of the
juvenile stem but then become reconnected later by
feeder roots which grow down from the upper internodes. Hemiepiphytic aroids typically have anchor
roots as well, and are thus often called “root climbers”.
Flagelliform shoots, heteroblastic leaf development
and shingle plants (see chapter 2) are characteristic features of hemiepiphytic Araceae, though not present in all
species of each genus. Highly developed heteroblasty
coupled with skototropism, a specific growth strategy
for seeking host tree boles, has been described in
Monstera (Madison 1977a, Strong & Ray 1975). In certain
species the seedling is a very slender, non-photosynthetic plant with long internodes and minute scale leaves.
Having germinated on the forest floor it seeks the defined
area of shadow represented by the nearest tree bole.
Once the tree has been reached the plant transforms
itself into the shingle form and later, higher up, into a
mature flowering plant. Vegetative reproduction may
then take place by the production of flagelliform shoots.
Seed size is almost certainly an important element in the
growth strategies adopted by hemiepiphytes. In Monstera
seeds are relatively large and lack endosperm, which
probably increases the efficiency and duration of the
seedling’s nutrient supply until it has reached a suitable
habitat for photosynthesis. Other hemiepiphytes which
produce flagelliform shoots have numerous very small
seeds and endosperm (e.g. Philodendron fragrantissimum, Rhodospatha latifolia) and probably have a
different kind of seedling development. More observations are needed, especially in tropical Asia. To date the
most important ecological observations of hemiepiphytic
aroids have been made in tropical America (Blanc 1977a,
b, 1978, 1980; Madison 1977a, Ray 1986, 1987a–c, 1988,
1990) and tropical Africa (Knecht 1983).
Cercestis (e.g. C. mirabilis) and Philodendron (e.g. P.
linnaei), among other genera, have species with another
growth strategy aptly termed “rhythmic growth” by Blanc
(e.g. 1977a). The mature flowering region of the stem is
short with abbreviated internodes and more-or-less rosulate foliage leaves. The continuation shoot climbs
upwards and is slender and flagelliform with cataphylls
instead of foliage leaves. After an interval it produces
another rosulate-leaved mature zone. The repetition of
this pattern produces a series of connected rosulate
plants one above the other on a single tree trunk.
Epiphytes
True epiphytes, which never become connected to
the ground by feeder roots, are found in Anthurium,
Arophyton, Philodendron, Remusatia, Scindapsus and
Stenospermation. The seeds presumably germinate
directly on the host tree after dispersal by birds or
other animals. Many species of Anthurium sect.
Pachyneurium (e.g. A. hookeri) and some
Philodendron species (e.g. P. insigne) are litter basket
epiphytes. The large leaves form an inverted cone in
which leaf litter and other debris accumulate and into
which the roots grow and ramify in a dense mass.
Remusatia vivipara, which has a tuberous stem, is a
widespread epiphyte, due to the dispersal of hooked
bulbils which are probably transported by birds and
primates high in the forest canopy. Arophyton buchetii
appears to occur only as an epiphyte in leaf litter accumulated within large Pandanus crowns.
Lithophytes
Many hemiepiphytes, epiphytes and geophytes are
also found as lithophytes in suitable conditions. Certain
groups, such as the Anthurium coriaceum complex in
eastern Brazil, are characteristically lithophytic. Different
species of this complex grow in humid coastal forests
(e.g. A. coriaceum) where they are common on exposed
areas of outcropping rocks, and in the semi-arid interior
(A. erskinei), where they survive exposure during the
prolonged dry season. Vining hemiepiphytes frequently
grow on rocks in forest regions wherever shade and
humidity are sufficient, the rock surface providing much
the same conditions for attachment as tree boles.
A number of geophytes are characteristically found
growing in the eroded, litter- or humus-filled cavities
of limestone outcrops; examples are Amorphophallus
albispathus, Colocasia gigantea, and Typhonium albispathum in S.E. Asia and Amorphophallus hildebrandtii
Carlephyton and Colletogyne in Madagascar.
Rheophytes are also typically lithophytic.
Geophytes
This category includes all genera with tuberous,
rhizomatous, subterranean or partly subterranean
stems. Geophytic aroids characteristically have periodic dormant periods when no leaves are present
and these normally correspond to the dry season (or
winter) of their habitat. However, rainforest geophytes
exhibit growth periodicity and dormancy even in nonseasonal climates, e.g. Amorphophallus maculatus,
A. titanum, Asterostigma riedelianum, Dracontium
prancei, Zomicarpella amazonica.
Several genera occur in more than one kind of climatic regime. In Stylochaeton, the rainforest species S.
zenkeri is evergreen with unthickened roots and the
inflorescence appears with the leaves. Other species,
such as S. natalensis, grow in areas with a strongly
marked dry season during which they are dormant.
This species has thick, fleshy roots and usually flowers before the leaves or just as they emerge. The
genera Amorphophallus and Dracontium are similarly
diverse ecologically, with species in rainforest or in
seasonal evergreen forest, deciduous forest, savannas
or grasslands (A. abyssinicus, D. margaretae).
ECOLOGY AND LIFE FORMS
45
1-22 Section A Acro 18/7/97 8:02 Page 46
Geophytes from deciduous forests, savannas or
strongly seasonal grasslands flower without the leaves
at the end of the dry season, mostly after the first rains
fall. Leaf and fruit development take place during the
rainy season. Variations occur in this basic phenological pattern. Biarum davisii (Crete and Turkey) flowers
in the autumn (± November) after the rainy season
has started, whereas B. ditschianum (Turkey) flowers
at the end of the rainy season (± May) and the fruit
development then takes place over a year (Bogner &
Boyce 1989). The Mediterranean species of Arum (e.g.
A. dioscoridis, A. italicum) grow during the relatively
warm winter rainy season, whereas the more northerly
A. maculatum grows from spring to summer and is
dormant during the cold winter (Boyce 1993a).
No Araceae occur in true deserts except Eminium
spiculatum subsp. negevense, from the Negev desert
(Koach 1988). Some species, however, grow in very dry
areas, e.g. Arum and Eminium in central Asia, Arum and
Biarum in North Africa and Asia Minor, Arisaema and
Sauromatum venosum in the Arabian Peninsula and
East Africa and a few Stylochaeton species of the Sahel
zone of Africa. All these regions normally have some
rain each year during which the plants grow vegetatively, or they may occur in places with a ground water
supply. Zamioculcas zamiifolia is a succulent plant
which stores water in its thick petioles and is sometimes found in very dry habitats, but it is more common
in evergreen seasonal forests and savannas.
Rheophytes
Rheophytes are flood-resistant plants, usually of tropical rainforests, growing in or along swift-running streams
or rivers up to the flood level. They are characterized by
narrow, leathery leaves and a firmly attached, usually
epilithic stem. In addition to tribe Schismatoglottideae, in
which the majority of genera have this habit, rheophytes are also found in Homalomena, Anubias and
Holochlamys, and rarely in Anthurium.
Submerged or periodically submerged aquatics
Jasarum steyermarkii and many Cryptocoryne species
are permanently submerged plants (hydrophytes, sensu
Cook 1990). Either the inflorescence as a whole
(Jasarum) or its upper portion (Cryptocoryne) is held
above the water surface while all other parts are completely submerged. Cryptocoryne is the largest genus of
aquatic aroids and merits more detailed consideration.
There are a number of species which are usually submerged but which are emergent at times of exceptionally
low water (C. affinis, C. aponogetifolia, C. purpurea).
The submerged leaves of such species are relatively
large, whereas the emergent leaves are quite small, indicating that such conditions are unfavourable to their
growth. The submerged and emergent leaves of the same
46
THE GENERA OF ARACEAE
species generally look very different in shape, size, colour
and structure. Submerged leaves are softer and emergent
ones more coriaceous. Many species occur in the freshwater tidal zone where there is a daily cycle of exposure
and submersion. Some species are found only in freshwater, like C. ferruginea, C. lingua and C. pontederiifolia,
while others can grow both in fresh and brackish water
(C. ciliata). A few species are helophytes, preferring
swampy conditions and growing during the dry season
completely emergent in normal soil, like C. spiralis, a
weed of rice fields in India. Usually Cryptocoryne species
flower at low water level when the plants become emergent. Cryptocoryne consobrina occupies a somewhat
more specialized niche. The leaves are present only during the monsoon season when the streams are in flood.
Flowering occurs after the monsoon rains when the
streams have dried up and the leaves are shrivelled.
During the dry season the plants are completely dormant
with the rhizomes buried in the soil. C. nevillii flowers
at the beginning of the monsoon season before the
leaves appear or as they emerge.
Helophytes
About 38 genera are helophytic or have at least
some helophytic species, i.e. plants which grow in
swampy habitats or along river and stream margins.
Four of these genera (Gearum, Mangonia,
Scaphispatha, Spathicarpa) are geophytes which habitually or frequently grow in seasonally flooded sites,
Nineteen genera are strictly helophytes or are aquatics
with some helophytic species (e.g. Cryptocoryne).
This life form is thus widespread throughout the
family in many different taxonomic groups, and in both
temperate and tropical genera. There is little constancy
in habit type. The stem may by tuberous (e.g. Caladium,
Typhonium), rhizomatous (Typhonodorum), rhizomatous and arborescent (Montrichardia), semi-prostrate
to aerial (Lasia), erect and arborescent (Philodendron)
or merely shortly erect and aerial (Homalomena).
The helophytic life form may be considered relatively
unspecialized in the majority of genera which exhibit it.
Tuberous or rhizomatous stems may be associated with
seasonally flooded habitats and a marked dry season.
Rhizomes may, on the other hand, be adaptations for colonizing muddy riverine margins as in the case of the
strict helophytes Typhonodorum and Montrichardia.
Genera such as Dieffenbachia, Homalomena and
Spathiphyllum exhibit no special adaptations in their
helophytic species, which appear to take advantage of
wetter habitats for more vigorous growth rather than
because of a strict requirement for a flooded substrate.
Free-floating aquatics
The only free-floating species of Araceae is the
pantropical Pistia stratiotes.
C
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C
13 P O L L I N AT I O N B I O L O G Y
Recent reviews of pollination biology and flowering
phenomena have been given by Grayum (1984, 1986b,
1990) and Meeuse & Raskin (1988). Few thorough
studies have yet been made of araceous pollination
biology, though this is clearly a field of the utmost
interest; most of the unusual and important taxonomic
characters of aroid inflorescences and flowers are
probably linked in one way or another to floral biological adaptations. Detailed studies of tropical genera
have mostly been published only in recent years:
Williams & Dressler (1976) for Spathiphyllum, Ramirez
& Gomez (1978) for Monstera, Silva (1981) for Pistia,
Shaw & Cantrell (1983) for Alocasia macrorrhizos,
Gottsberger & Amaral (1984) for Philodendron and
Young (1986) for Dieffenbachia. For temperate genera
there are the classic studies of Arum by Knoll (1926)
and Prime (1960), Vogel’s observations of fungus gnat
pollination in Arisaema and Arisarum (Vogel 1978)
and various studies of Arisaema (e.g. Barnes 1934,
Bierzychudek 1982). Only Young (1986) and
Bierzychudek (1982) have studied pollination biology
in relation to entire populations of plants of the same
species. There is a large literature which reports less
critical studies or observations of insect visits to
Araceae inflorescences. The phenology and behaviour of the spathe, spadix and flowers during anthesis
are also subjects which in general have not been studied critically. Notable exceptions are the studies of
Knoll (1926, Arum), Croat (1980, Anthurium), Gottsberger & Amaral (1984, Philodendron) and Meeuse &
Raskin (1988, Sauromatum).
Araceae inflorescences are almost always insect
pollinated, although “wind tunnel” pollination has been
proposed for Pinellia (Uhlarz 1985). The pollinators of
Acorus (Acoraceae) are still unknown. Pollinators so far
reported for Araceae (see Table 2) include trigonid
bees, euglossine bees, beetles, flies, possibly thrips
and very doubtfully mites.
Some species of drosophilid flies are known to
breed on the inflorescences of Alocasia, Colocasia
and Homalomena (Okada 1986). They also exhibit
specialization in their behaviour even on the spadix of
a single species: stamenicolous species lay their eggs
in the male zone while pistilicolous species lay their
eggs in the female. Furthermore, several different pairs
of fly species, one stamenicolous and the other pistilicolous, are known to breed in association on one
aroid species (synhospitality).
The trap mechanisms of genera with unisexual
flowers and relatively complex spathes (e.g. Arum,
Arisaema, Arisarum, Philodendron) have attracted
most attention in pollination studies. Much less is
known about pollination mechanisms in genera with
bisexual flowers and simpler or spreading spathes
(e.g. Anthurium, tribe Monstereae, many Lasioideae).
While “trap” seems an accurate description in Arum,
Arisaema and Cryptocoryne, it is less clear in other
genera (e.g. Amorphophallus, Philodendron) whether
the pollinators are unable or merely unwilling to leave
the inflorescence, once they have entered it, kept
there perhaps by possible attractants such as stigma
secretions, food bodies or sites for reproduction.
Odour is evidently a prime factor in attracting
pollinators and while Araceae are famous for foul
inflorescence odours, which have been compared to
dog faeces, horse dung, rotten fish, old socks, sulphurous gas, dead cow, mushrooms, cheese, etc.,
many others are not foul-smelling. Floral odours in
Philodendron, Spathiphyllum and Xanthosoma are
heavy and spicy and in Anthurium range from spicy
to the smell of decaying fruit. At least two species of
Amorphophallus are known to have a pleasant floral
odour (A. galbra, A. manta). The wide range of
odours must be correlated with different kinds of
pollinator but though some studies of odour chemistry have been made (e.g. Meeuse 1966b, 1978,
1985), this fascinating field is largely unworked from
a comparative standpoint.
The colour of the spathe, and to a lesser extent of
the spadix, varies considerably within the family,
ranging from inconspicuous greens (e.g. Anthurium,
Nephthytis) to elaborate patterns (e.g. Colletogyne,
Sauromatum) or striking “flags” (e.g. Anthurium
andraeanum). In fly pollinated species the spathe
colours and patterns are known to be important in
attracting pollinators (myriophile colours).
Differentiated colour zones are frequent: in
Philodendron many species have purple zones inside
the spathe tube, while the blade is white or pale
green. In Arisaema and Arisarum, the reverse situation is found, with white spathe tubes and dark
purple blades which are often striped. The foul
odours of such species as Amorphophallus konjac
are very often associated with flesh-coloured or livid
spathes, resembling carrion. By contrast,
Zantedeschia aethiopica and many Spathiphyllum
species have pure white spathes and perfumed
inflorescences from which euglossine bees collect
fragrances. This also occurs with naturalized
Zantedeschia in tropical America (G. Gerlach pers.
comm.). Trigonid bees collect pollen which also
attracts certain beetles, e.g. Nitidulidae, that eat the
fertile male flowers of Aridarum nicolsonii (Bogner,
pers. obs.)
POLLINATION BIOLOGY
47
1-22 Section A Acro 18/7/97 8:02 Page 48
Inflorescence heating (thermogenesis) in connection with flowering has been studied more, particularly
in Arum (Rees et al. 1976, 1977), Sauromatum
(Meeuse 1966a–b, 1975, 1978, 1985, Meeuse & Raskin
1988) and Philodendron (review by Mayo 1991).
Thermogenesis in other genera has also been studied
(e.g. Symplocarpus), but the only general comparative
surveys are by Leick (1914, 1916, 1921 and, briefly, by
Engler (1920b). While thermogenesis is very common
in Araceae it is by no means universal. Its function is
generally agreed to be to volatilize odour compounds,
and, more speculatively, thus to give precision both to
the duration of the period of pollinator attraction
(length of heating period), type of odour compound
utilized (molecular weight) and distance over which
pollinators can be attracted (maximum temperature).
In other genera, however, odours are produced apparently without heating.
Odour production and thermogenesis (when present) occur mainly in terminal appendices or in the
male zones of the spadix in those genera that lack
appendices (e.g. Philodendr on, Xanthosoma).
Table 2. Pollinators of Araceae. Data mainly from Grayum (1984, 1990).
48
euglossine bees
Anthurium, Spathiphyllum, Xanthosoma
trigonid bees
Monstera, Spathiphyllum, Amorphophallus
beetles: Asilidae
Amorphophallus
beetles: Cetoniidae
Amorphophallus
beetles: Curculionidae
Anthurium, ?Pistia
beetles: Dermestidae
Dracunculus
beetles: Nitidulidae
Alocasia, Amorphophallus, Anchomanes, Anubias, Aridarum, Cercestis,
Culcasia, Cyrtosperma, Nephthytis, Typhonium, Urospatha, Xanthosoma
beetles: Ptiliidae
Typhonium
beetles: Scaphidiidae
Pseudohydrosme
beetles: Scarabaeidae
Alocasia, Amorphophallus, Anubias, Caladium, Dieffenbachia, neotropical
Homalomena, Philodendron, Syngonium, Xanthosoma
beetles: Scydmaenidae
Typhonium, Zantedeschia
beetles: Silphidae
Amorphophallus
beetles: Staphylinidae
Alocasia, Amorphophallus, Anthurium, Chlorospatha, Dracunculus,
Lysichiton, Piptospatha, Pseudohydrosme, Typhonium
flies: Anthomyiidae
Alocasia
flies: Calliphoridae
Amorphophallus, Dracunculus, Helicodiceros
flies: Centropogonidae
Arum, Cryptocoryne
flies: Chloropidae
Peltandra
flies: Chorideae
Pseudohydrosme
flies: Drosophilidae
Alocasia, Colocasia, Culcasia, Homalomena, Nephthytis, Schismatoglottis
flies: Ephydridae
Cryptocoryne
flies: Neurochaetidae
Alocasia
flies: Phoridae
Cryptocoryne
flies: Psychodidae
Arum
flies: Sciaridae
Arisaema, Arum
flies: Simuliidae
Arum
flies: Sphaeroceridae
Arum, Pseudohydrosme
flies: Syrphidae
Peltandra
flies: Mycetophilidae
Arisaema, Arisarum
mites
Ambrosina (reported in literature but very doubtful as pollinators: fruit-set
is extremely rare and possibly the pollinators are extinct).
thrips (Heterothrips arisaemae)
Arisaema (reported in literature but doubtful)
THE GENERA OF ARACEAE
1-22 Section A Acro 18/7/97 8:02 Page 49
Unpleasant odours from the spathe have been
observed in Dracontium and in the spathe blade of
Lagenandra (Bogner pers. obs.) and Cryptocoryne
(Vogel 1963, 1990, Bogner pers. obs.). In the spathe
tube “kettle” of Lagenandra a different, fruity odour
is produced which emanates mainly from the anthers
and occasionally also from the so-called “olfactory
bodies” above the female flowers (Buzgó pers. obs.).
These structures are present only in Lagenandra and
Cryptocoryne and their function is still unclear. The
thickened connectives of stamens or synandria commonly found in several tribes of subfamily Aroideae
(e.g. Philodendreae, Homalomeneae, Anubiadeae,
Caladieae, Colocasieae) probably represent adaptations for osmophore function (see Vogel 1963, 1990
for an important survey of osmophores). In taxa with
well-developed terminal appendices (e.g. tribes
Thomsonieae, Areae, Arisaemateae) thickened connectives are usually absent. Odour production in
genera with bisexual flowers is much less well understood. In Spathiphyllum the stigma plays this role
(Vogel 1963, 1990, Williams & Dressler 1976) and in
Anthurium it is probable that the thickened tepal
apices are involved.
Araceae are always protogynous and the female
(stigma receptivity) and male (anther dehiscence)
phases usually do not overlap, so that obligate out-
crossing seems to be the general rule. Some cases of
self-pollination or apomixis are known or suspected
(Amorphophallus bulbifer, Anthurium bakeri, Pinellia,
some Arum).
Manipulation of pollinator behaviour within the
inflorescence may be the basis for many of the specialized features of the spadix, particularly in
unisexual-flowered genera. Spathe constrictions may
act as “skid zones” (Arum) or as “brooms” to eject
pollinators from the female chamber after pollination (Philodendron). The various types of hairs,
scales and warts found on the inner base surface of
the spathe (e.g. Amorphophallus) or the wide range
of staminodial or pistillodial structures on the spadix
(e.g. tribe Areae, Bucephalandra) have less obvious
functions. In Arum the filamentous pistillodes and
staminodes are thought to exclude inappropriately
large insect visitors while in Dieffenbachia the protein-rich staminodes have been shown to be food
bodies for scarab beetles (Young 1986). It is conceivable that at least some of these structures are
also osmophores which create odour gradients within
the inflorescence itself. Certain structures, like the
filamentous projections on the spadix appendix and
spathe of Helicodiceros, mimic characteristics of animal corpses normally used by the pollinating insects
for egg deposition or breeding.
POLLINATION BIOLOGY
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49
1-22 Section A Acro 18/7/97 8:02 Page 50
14 D I S P E R S A L
C
The seeds of most Araceae do not remain viable for
long. Those lacking endosperm and with large
embryos cannot withstand dessication and the genera
with fleshy testas are similarly vulnerable. In certain
species, however, the seeds can withstand dessication
for longer periods, e.g. Philodendron bipinnatifidum,
which can remain viable for over 12 months (Mayo,
pers.obs.). Seeds with a leathery testa, such as in Arum
and Arisaema, also have longer viability. One consequence of short viability is that Araceae seeds are
unlikely to survive long distance dispersal by natural
vectors. This makes it unlikely that generic disjunctions
over major ocean basins have resulted from long distance dispersal. Islands located far from continental
areas tend to be very poor in native Araceae or lack
them altogether, e.g. most islands of the Pacific. In
Sauromatum venosum and Remusatia vivipara, however, long distance dispersal may well be the cause of
their widely scattered Old World distribution patterns.
Little is known of the viability of Sauromatum seeds,
but its purple berries are very probably dispersed by
birds, since in upland forests it often occurs as epiphyte. Remusatia vivipara, also epiphytic in upland
forests, is almost certainly distributed mainly by means
of its peculiar bulbils, which are burr-like with
recurved scales.
Another important generalization that can be made
is that animal dispersal, and more specifically, ornithochory (bird dispersal), must be the dominant mode,
due to the universality of berried fruits in Araceae.
Reliable data on dispersal is very scarce, a recent
exception being that of Barbara and David Snow
(1988) for bird dispersal by blackbirds (Turdus merula)
and robins (Erithacus rubecula) of Arum maculatum
in England. Peckover (1985) observed in Papua New
Guinea that captured birds of paradise (magnificent
riflebird: Ptiloris magnificus) fed on fruits of
Amorphophallus paeoniifolius and regurgitated seeds
about four hours later. Glossy-mantled manucode bird
of paradise (Manucodia atra) was also observed on an
infructescence of Amorphophallus paeoniifolius and
was presumed to be feeding rather than merely perching. If a similar delay between feeding and
regurgitation also occurs in the wild a wider dispersal
could thereby be achieved. Indigenous people (the
local Batak population) have observed hornbills
(Bucerotidae) eating berries of Amorphophallus
titanum, and the bulbul bird (Pycnonotus zeylanicus)
feeding on the berries of A. brooksii in Sumatra
(Hetterscheid, pers. comm.). T. Lamb (pers. obs.) has
added support to this evidence by his own observations of bulbul birds eating berries of A. lambii in
50
THE GENERA OF ARACEAE
Sabah. Shaw et al. (1985) reported Lewin’s honeyeater
birds (Meliphaga lewinii) and regant bowerbird
(Sericulus chrysocephalus) eating the ripe berries of
Alocasia brisbanensis (as “A. macrorrhiza”) in eastern Australia. It is not known if the seeds are
regurgitated, destroyed in the gizzard or stomach, or
voided intact in the faeces. Circumstantial evidence for
other genera points to birds (Anthurium) and mammals, including primates (Anchomanes, Philodendron)
and bats (?Philodendron), as the commonest vectors.
The tawny-capped euphonia (Euphonia anneae) was
reported to feed heavily on fruits of Anthurium
(Loiselle & Blake 1990). Wheelright et al. (1983)
observed three different birds (resplendent quetzal:
Pharomachrus mocinno, long-tailed manakin:
Chiroxiphia linearis, common bush tanager:
Chlorospingus ophthalmicus) feeding on three unidentified species of Anthurium. A fecal sample of the
wood thrush (Hylocichla mustelina) was observed containing seeds of an unidentified species of
Dieffenbachia by Blake & Loiselle (1992).
The common palm civet (Paradoxurus hermaphroditus) is reported to disperse the seeds of Colocasia
esculenta in Indonesia (Hambali 1980). Marks were
left on the peduncle by the claws and teeth of this
mammal and germinating seeds of two cultivars of C.
esculenta were seen in its excreta. This is the only
report seen that records the passage of viable aroid
seeds through the digestive system of an animal.
Hambali (1980) confirmed an earlier report by
Leeuwen (1932) that seeds of Colocasia gigantea were
dispersed by the common palm civet, and Hambali
(1980) also stated that ripe fruits of Homalomena pendula are usually eaten by the same animal. The fruits
of all three aroid species are odoriferous, which may
attract the civet (Hambali 1980).
Presentation of the fruits for dispersal is normally
a rather sudden event. In Philodendron and
Dieffenbachia the spathe falls off or splits at maturity
to reveal the infructescence, whereas in genera with
non-persistent spathes the berries remain inconspicuous during maturation and take on their bright
colours in a final rapid flush. In Anthurium the berries
are extruded from the perigone at maturity and in
most species dangle by tiny threads of tepal epidermis. This mode of presentation has also been
observed in Cyrtosperma by Hay (1988). The bright
colours, sticky gelatinous mesocarp and mode of presentation in such species strongly suggests bird
dispersal. In other, terrestrial or rupicolous species,
e.g. Anthurium erskinei, the inconspicuous greenish
berries merely fall into a heap onto the ground, sug-
1-22 Section A Acro 18/7/97 8:02 Page 51
gesting some other kind of vector. Genera of subfamily Monsteroideae display the seeds by
simultaneous abscission of the stylar region of each
flower. The resulting compound mature fruit has the
seeds embedded in sticky, often sweet and mucilaginous material. T. Croat (pers. comm.) has suggested
that these fruits may be dispersed by monkeys.
Philodendron subgen. Meconostigma has fruits with
a similarly sweet, pineapple to mango flavour and
some of its Brazilian vernacular names suggest
mammal dispersal agents (“monkey’s banana” or
“bat’s banana”). Black spider monkeys (Ateles paniscus) have been observed eating the infructescences
of Philododendron goeldii (Bogner, pers. obs.). In
Anthurium, Dieffenbachia, Nephthytis and other
genera, the berries are often sufficiently distant
from one another within the infructescence to be dispersed individually. Mature berries in Arum and
Nephthytis have been observed to remain for a relatively long time awaiting dispersal. In contrast the
dense infructescences of Caladium, Colocasia,
Philodendron, Syngonium, may disappear very soon
after exposure.
Dispersal by ants (myrmecochory) has been
observed in Biarum, in which the strophiole of the
seed is probably implicated. In the tropics it is likely
that ant dispersal is involved in the occurrence of certain aroids in Amazonian root gardens (e.g.
Philodendron megalophyllum (syn. P. myrmecophilum),
Anthurium ernestii, A. gracile; see Ule 1905).
Anthurium gracile is a characteristic plant of ant-gardens (Benzing in Huxley & Cutler 1991). T. Croat (pers.
comm.) has observed ants dispersing seeds of
Philodendron megalophyllum.
Dispersal by water (hydrochory) is very probable in
the helophytic genera Montrichardia and
Typhonodorum, which have very large berries and
floating seeds. Lagenandra, Cryptocoryne and Pistia
are certainly water-dispersed and have much smaller
fruits and floating seeds.
DISPERSAL
C
51
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15 G E O G R A P H Y
C
Reviews of araceous geography have been published
recently by Croat (1979), Grayum (1990), Hay (1992b)
and Mayo (1993). Individual generic distributions are
given in the maps, generic treatments and country
lists (Appendix).
The genera of Araceae are concentrated in the
tropics of America, Southeast Asia and the Malay
Archipelago (we include under this designation
Malaysia, Indonesia, the Philippines, Papua New
Guinea, Singapore and Brunei). Continental tropical
Africa is the next richest region, followed in order of
decreasing diversity by temperate Eurasia, southern
Africa, Madagascar and the Seychelles, and North
America (including northern Mexico). Australia has
two endemic genera (Gymnostachys, Lazarum). The
other native Australasian genera (in northern
Australia) are essentially extensions of the tropical
Asian and Malay Archipelago flora.
The vast majority of genera are endemic to the
major regions (as given above), but some extend further. Pistia is pantropical and Calla is circumboreal
in the northern hemisphere, reaching as far as the
subarctic zone in northern Scandinavia. Arisaema is
the most widespread genus of more than one species.
It is most diverse in south-west China, and extends
west as far as Tanzania and Burundi, and east to
eastern North America and northern Mexico.
Amorphophallus, Remusatia, Rhaphidophora and
Sauromatum are shared between tropical and subtropical Africa and Asia and the Malay Archipelago.
Amorphophallus and Remusatia also occur in
Madagascar and northern Australia. Pothos is found
in Madagascar as well as in tropical Asia, Malay
Archipelago, northern Australia and the western
Pacific. Lysichiton and Symplocarpus occur in northeastern Asia as well as in temperate North America,
52
THE GENERA OF ARACEAE
Lysichiton reaching subarctic latitudes in Alaska. An
unusual pattern is shown by the close taxonomic
relationship of Peltandra (eastern North America)
and Typhonodorum (Madagascar).
Certainly the most interesting feature of araceous
geography is the occurrence of three genera
(Homalomena, Schismatoglottis and Spathiphyllum)
with ranges disjunct between the Malay Archipelago or
Melanesia and tropical America. These are all rainforest herbs for which long-distance dispersal by water or
suitably far-ranging animal vectors is probably impossible. It is also difficult to imagine these genera being
rafted by the southern Gondwanic route (Chile,
Antarctica, Australia, New Zealand) or via the Bering
Straits because of their intolerance of even subtropical
conditions, much less temperate climate. Their patterns of diversity are dissimilar. While Homalomena
and Schismatoglottis are most diverse in southeast Asia
and Malesia, Spathiphyllum is richest in tropical
America. No really plausible historical explanation has
yet been proposed for these disjunctions, nor for those
of other taxa with this kind of range, such as Sloanea
(Elaeocarpaceae) and Heliconia (Heliconiaceae).
Nevertheless, it is tempting to speculate that these patterns are the relicts of a once-continuous distribution
in Gondwanaland during the Cretaceous period.
A number of species which are important as food
(Colocasia esculenta, Cyrtosperma merkusii,
Xanthosoma sagittifolium complex) or ornamental
plants (Alocasia macrorrhizos, Epipremnum pinnatum
‘Aureum’, Monstera spp., Philodendron spp., Syngonium
spp., Zantedeschia aethiopica) have been widely dispersed throughout the tropics by man and have become
naturalized as well. Some Typhonium species (Nicolson
& Sivadasan 1981) have become widely dispersed and
weedy in many parts of the tropics.
1-22 Section A Acro 18/7/97 8:02 Page 53
C
16 U S E S
Bown (1988) gives an excellent general account of
useful aroids to which the reader is referred for
greater detail.
Food plants
The most important food aroids are from tribes
Colocasieae and Caladieae, i.e. Colocasia and
Xanthosoma. The great majority of Araceae are poisonous when fresh and in almost all cases, edible
species must be cooked or processed in some way
before they can be used as food.
Recent technical reviews of edible aroids, especially
taro, are given by Wang (1983) and Chandra (1984).
Colocasia esculenta, the taro plant, originated in tropical Asia and has been cultivated there for more than
2000 years. Its original geographical range is obscure,
but Assam and Burma are likely possibilities. Today it
is an important root crop in most humid tropical countries, especially in the Caribbean, Africa, Madagascar,
Asia and the Pacific Islands. The tuberous stem is a rich
starch source (13% to 29% by weight, depending on the
cultivar), and the leaves of certain cultivars are widely
eaten as a spinach. Taro tubers are also richer in protein than most other major starch crops and provide
very nutritious food (Chandra 1984). When fresh, all
parts of the plant are poisonous and must be cooked,
roasted or heated in some way to become edible. The
uncooked tissues contain an irritant toxin which can
burn the skin (see chapter 11).
Colocasia esculenta is known by a plethora of
local vernacular names which correspond to the many
different land races and cultivated varieties that have
evolved by human selection. The species is most
widely known today as taro, its name in the Pacific
Islands. In some varieties the flesh of the tuberous
stem is white or yellow while in others it is violet; the
latter are sometimes preferred for their stronger
flavour. Some cultivars are used as animal food, especially for pigs. Cultivars with tubers rich in
mucilaginous material tend to be used for animal feed
while those with a lower mucilage content are used
for human consumption.
The neotropical genus Xanthosoma also contains
species which are very important food plants, particularly Xanthosoma sagittifolium. This and other
species are widely cultivated, not only in tropical
America but also in tropical Africa and Asia. As in
Colocasia esculenta, both leaves and starch-rich tubers
are used and can only be eaten after cooking. Plant
remains from ancient Peruvian graves have been iden-
tified as Xanthosoma, showing that Xanthosoma must
have been cultivated as a food plant in precolumbian
times (Costantin & Bois 1910, Towle 1961).
Xanthosoma sagittifolium is most widely known as
cocoyam. There are many other names associated
with the other species used for food, X. violaceum, X.
atrovirens, X. mafaffa (used especially in Nigeria,
Okeke 1992), X. brasiliense, X. caracu and X. robustum. These are all more-or-less closely related to X.
sagittifolium, but much taxonomic confusion currently reigns in this group of taxa and needs to be
clarified urgently (S. Thompson, pers. comm.).
Alocasia macrorrhizos, the giant taro, was widely
used for animal fodder in the nineteenth century and
more rarely for human food. The stems have relatively
little mucilaginous material and are eaten after roasting.
They are said to be tasty when warm but irritant and
unpleasant when cold. The stems may grow to as long
as 5m and contain abundant latex.
The starch-rich tubers of the elephant yam,
Amorphophallus paeoniifolius (syn. A. campanulatus),
are commonly used as food in tropical Asia, especially
in India, where the species is widely cultivated. The
tubers may reach 10 kg in weight and are eaten after
roasting or boiling, like potatoes. In the Malay Peninsula
the tubers of Amorphophallus prainii are also eaten
after cooking, but must be sliced and soaked in water
beforehand.
Amorphophallus konjac (syn. A. rivieri), the konjac
plant, is widely cultivated in Japan. The mannan-rich
tubers (see chapter 11) are harvested after 1 to 3 years.
They are boiled in water and then treated with lime
milk to make a flour from which noodles (chira take) or
cakes (chiroko) are prepared. A jelly (nama konjaku) is
also made from the lime milk preparation and the gumlike juice can also be used to make glue. Konjac flour
is traditionally prepared by slicing the raw tubers into
5mm thick pieces and then drying them in the sun for
a week or so until the water content is reduced from
about 90% to about 15%. The dried material is then
pounded into a flour. Modern methods to extract konjac mannan involve washing the flour with 70% ethanol
in a nylon filter or by acetylation. The quality of the flour
differs according to the plant variety, the area in which
it is grown and the method of preparation. The rigid gels
prepared from the flour also vary according to the
source of the raw material. The three main varieties of
konjac cultivated in Japan are: ‘zairai-shu’ (traditional
cultivar), ‘shina-shu’ (Chinese cultivar) and ‘bicchu-shu’.
The thick, starch-rich rhizomes of Cyrtosperma
merkusii (swamp taro) are used for food in Southeast
Asia and the Pacific Islands where the plant is grown in
USES
53
1-22 Section A Acro 18/7/97 8:02 Page 54
nutrient-poor sites unsuitable for the main starch staple,
Colocasia esculenta. The tubers of various species of
Dracontium have been recorded as a food source for
Amerindians; preparation is by roasting.
The fresh, ripe infructescences of Monstera deliciosa are eaten and used to flavour ice cream in
Mexico; the taste recalls that of pineapple. The trichosclereids in the rind of the infructescence are
troublesome and the wider use of this delicious fruit
is hampered by lack of better cultivars. In Brazil, the
infructescences of Philodendron bipinnatifidum are
occasionally eaten by man (Crisci & Gancedo 1971);
they have a mango-like flavour and a slightly irritant
after-taste.
The seeds of Typhonodorum lindleyanum and
Montrichardia linifera are recorded as having been
eaten by indigenous peoples of Madagascar and tropical South America respectively, after cooking or
roasting. The seeds of Orontium aquaticum were
eaten after drying and boiling by North American
indigenous people.
Theophrastos recorded the use of tubers of Arum
italicum as a source of food starch in ancient Greece.
In the Middle Ages, tubers of Arum maculatum were
used as famine food, especially in England. North
American Amerindians are known to have made a flour
from the tubers of Arisaema triphyllum, but neither
Arum nor Arisaema appear to be used for these purposes today.
family as a whole. The various medicinal uses of aroids
described by Bown include external healing of stings,
wounds, skin complaints and arthritis, expectorants and
decongestants, contraceptives, parasite insecticides, anticancer agents, sedatives and hallucinogens. Acorus
(Acoraceae) has a long history of use as a medicinal
plant for problems of the digestive system and the scientific literature that exists on the subject is extensive
(see Röst 1978, 1979a, b, Röst & Bos 1979)
Toxic effects in Araceae are widely known and
have received some attention from chemists (see chapter 11). The effects of the highly toxic Dieffenbachia
are the best known and most completely studied.
Araceae are used in arrow poisons and fish toxins
(Bown 1988).
Magical and ritual uses of aroids are known, but little studied. The use of Dieffenbachia and Caladium to
ward off the “evil eye” is widespread in Brazil.
Fibres
The roots of Heteropsis and Philodendron have
been used for fibres in tropical South America.
Heteropsis spruceana is still today an important source
of twine and basket-weaving material in Brazilian
Amazonia. The stems of Montrichardia linifera provide
a fibre which is suitable for paper-making. Bown
(1988) reports the use of fibres from species of
Anthurium, Cercestis, and Gymnostachys anceps.
Medicinal, toxic and magical uses
Ornamental uses
The ethnobotany of the Araceae appears to be
diverse and fascinating, judging from the many circumstantial reports which are scattered through the scientific
literature. No comprehensive modern review exists and
none is attempted here. However, valuable contributions have been made by Plowman (1969) and Croat
(1994) for the New World and particularly by Bown
(1988), who gave an excellent modern account for the
54
THE GENERA OF ARACEAE
Araceae are best known as ornamental plants and
commercially are among the most important foliage
ornamentals cultivated and sold for display. Their beautiful and unusually diverse leaf forms and textures form
an essential part of any tropical plant display. In the
tropics they are universally seen in private and public
gardens. Further details are given in chapter 17.
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17 C U L T I VAT I O N
Crops
The major crop species are Colocasia esculenta (taro),
Xanthosoma sagittifolium (cocoyam), Cyrtosperma
merkusii (swamp taro), Alocasia macrorrhizos (giant
taro), Amorphophallus paeoniifolius (elephant yam) and
Amorphophallus konjac (konjac).
The cultivation methods of major aroid crop species
are dealt with in some detail by Wang (1983) and
Chandra (1984), which also give extensive bibliographies of the subject; Bown (1988) gives a very readable
and informative account. Colocasia esculenta,
Xanthosoma sagittifolium and Cyrtosperma merkusii
are generally grown in humid conditions, although
some varieties of Colocasia esculenta are also suitable
for drier sites. Their preference for moisture makes
these species especially suitable for humid tropical
subsistence farming on sites unsuitable for other kinds
of food crop. Amorphophallus paeoniifolius and A.
konjac are grown in shade and on well-drained soils.
Ornamental Araceae
Temperate genera
Many hardy Araceae do best in shady and half
shady sites with humus-rich soil and are therefore very
suitable for temperate woodland gardens. This group
includes species of Arisaema, Arisarum (with winter
protection by leaf litter), Arum, Dracunculus and
Pinellia. In cultivation they prefer leaf litter on the soil
surface and this also protects the tubers or rhizomes
from frost in winter. Growth starts in the spring or wet
season and dormancy sets in during the autumn or
dry season. They are suitable for growing with ferns
and other shade-loving plants. Smaller species can also
be grown in shady parts of rock gardens. Half hardy
species can be grown in pots and overwintered in
frost-free conditions. Pinellia ternata easily becomes
weedy by vegetative propagation from the bulbils
which form on the petioles.
Biarum, Eminium and some Arum species thrive
best in the rock garden, with stony, drier soils and
sunny sites on walls or between rocks, but they require
some protection in winter. Helicodiceros, a
Mediterranean genus, is not quite hardy and the tubers
need to be well protected during a temperate winter.
One way to do this is to remove them from the soil and
keep them frost-free and dry in sand.
Other genera are best grown in wet places, like
bog gardens, along streams, in pools or on the margins
of a pond. These include Acorus (Acoraceae), Calla,
Orontium, Lysichiton, Peltandra and Symplocarpus.
They do well in a nutrient-rich, loamy soil in a sunny
or half shaded position. Calla prefers a more acid habitat in shaded or partially shaded sites. Orontium does
best in full sun. Propagation is mostly by seed in
Lysichiton, Orontium and Symplocarpus. Acorus and
Calla are easily propagated by dividing the rhizomes.
In Europe, naturally occurring Acorus calamus is
triploid and cannot set seed. Division of Lysichiton,
Orontium and Symplocarpus is best not attempted
because their rhizomes are situated rather deeply and
should not be disturbed.
Tropical genera
In tropical countries Araceae have an important role
as ornamental plants. They are cultivated in public
parks as well as in private gardens or as house plants.
Under these favourable conditions they are easily
grown and need little care beyond regular watering in
regions with a drier climate. Their varied life forms provide magnificent climbers, bedding and large, sculptural
terrestrial plants. Commonly cultivated aroids in tropical countries include species of the genera Aglaonema,
Alocasia, Anthurium, Caladium, Colocasia,
Dieffenbachia, Epipremnum, Homalomena, Monstera,
Philodendron, Rhaphidophora, Schismatoglottis,
Scindapsus, Spathiphyllum, Syngonium, Xanthosoma
and Zantedeschia (especially at higher altitudes). Lasia
spinosa, Typhonodorum lindleyanum, Montrichardia
linifera and M. arborescens are often cultivated in or
beside ponds where because of their large size they
form impressive and unusual-looking stands. Pistia stratiotes is often grown in ponds and lakes. The geophytic
(tuberous and rhizomatous) tropical Araceae are only
seldom cultivated in gardens, perhaps because they
require more care.
In temperate regions, tropical genera are very
important as house plants and are raised and sold on
an industrial scale. Nearly every apartment or house in
Europe and the Americas has at least one aroid as an
ornamental plant. These, the best known and most
widely grown aroids, tolerate low light levels (especially important for surviving the winter), dry air from
central heating, irregular watering and general neglect,
all of which makes them suitable for cultivation as
house plants. A variety of Araceae is also grown in
hydroculture in large offices and public buildings.
Particularly well known house plant aroids belong to
the genera Monstera (M. deliciosa), Philodendron (P.
scandens, P. erubescens, P. bipinnatifidum and many
other species and hybrids), Dieffenbachia (many cultivars of D. seguine and D. maculata), Aglaonema
CULTIVATION
55
1-22 Section A Acro 18/7/97 8:02 Page 56
(many cultivars of A. commutatum, A. nitidum and
other species), Syngonium (cultivars of S. podophyllum,
often with variegated leaves), Zantedeschia (especially
Z. aethiopica and hybrids), Spathiphyllum (especially
S. floribundum, S. cannifolium and other species and
hybrids), Epipremnum (E. pinnatum ‘ Aureum’, also
known as Pothos aureus or Scindapsus aureus),
Anthurium (particularly A. andraeanum and A.
scherzerianum and cultivars) and Caladium (C. bicolor
and cultivars). Many species of Cryptocoryne are prized
by aquarists and species of Anubias are also widely
grown as aquarium plants.
Commercial nurseries that raise Araceae as house
plants are common in many parts of the world, perhaps the most important being the USA and the
Netherlands. Anthurium and Zantedeschia are the
major sources of aroid cut flowers and are cultivated
on a large scale. Anthurium andraeanum has a very
large number of cultivars differing in spathe colour
with various shades of red, pink, white and green and
in spathe texture and the attitude of the spadix.
Zantedeschia aethiopica and other species and their
hybrids have a range of spathe colours which includes
white, yellow, and various shades of red, and the
spathes vary widely in size and shape. Plants for the
cut flower market are cultivated in beds. Some are
grown in gravel for hydroculture (hydroponic) or in
ordinary, standardized or peat soils. Propagation is
usually vegetative by means of cuttings but for certain
cultivars tissue culture is also employed.
Tropical aroids are mostly evergreen and are forest
herbs, climbing hemiepiphytes or epiphytes in their natural habitats. Anthurium species grow best in conditions
of high humidity and a minimum temperature of
18–20°C, with a soil mixture of sphagnum moss and
fibrous peat. Dieffenbachia, Philodendron, Monstera
and Spathiphyllum can be grown in standardized soil
mixtures or specially made up composts composed of
sterilized soil, treated leaf mould or bark chips, peat
and sand with some balanced fertilizer. As a base, sandy
loam with added peat and sand can also be used.
Zantedeschia prefers a heavier, more loamy mixture.
Climbers like Philodendron, Monstera and Epipremnum
need a support on which to develop properly, such as
a bamboo stick, moss-covered stick, roughened wooden
billet or a suitable wall.
Much more care is required to successfully grow seasonally dormant genera with tubers or rhizomes and
these are consequently less commonly cultivated, e.g.
Anchomanes, Amorphophallus, Caladium, Gonatopus,
Dracontium, Remusatia, Synandrospadix, Taccarum,
Theriophonum, Typhonium and Xanthosoma sect.
Acontias. These plants must be kept dry during their
dormant period and they are best grown in pots with a
rather sandy compost in order to control soil humidity
better. They require regular and abundant water during
the growing period but watering must be reduced and
very carefully controlled at the beginning and end of
dormancy. While dormant the tubers are best kept dry
56
THE GENERA OF ARACEAE
in the old soil and left undisturbed, but they may also be
removed from the soil and stored in a shady, humid
place. Repotting should be carried out as the new roots
begin to develop, i.e. near the end of the dormant period
before the shoots appear. For example, in Europe the
tubers of Caladium bicolor are repotted in the early part
of the year (February, March) and grow during the summer until the end of August or September when they
re-enter dormancy. They must then be kept dry in the old
compost or removed entirely from the pot until the following year. Amorphophallus konjac, Colocasia esculenta
and Sauromatum venosum can be grown outside from
spring to autumn in central Europe. Propagation of these
genera is by seed or daughter tubers.
Cultivated tropical aquatics and helophytes include
Cryptocoryne, Cyrtosperma, Dracontioides, Lagenandra
and Urospatha. Most of these are grown only in a few
botanic gardens. The most difficult species to grow,
such as Jasarum and some species of Cryptocoryne, are
from nutrient-poor black water rivers. These species
require an acid soil and very soft water. Compost made
from siliceous rock (granite or gneiss) or acid peat or
leaf mould (especially from Fagus sylvatica) can be
used. For less demanding species a mixture of loam,
sand and peat or just sand and loam is sufficient.
Some Araceae which do not become completely
dormant need a drier period during which growth
more-or-less ceases. At this time, however, they
should not be allowed to dry out completely.
Zantedeschia aethiopica, for example, needs a resting
period in Europe between spring and summer (July)
when it should be kept in rather dry and sunny conditions. Following this the plant should be repotted
and watering gradually increased as the plant comes
into more active growth. Other species (e.g. Z. albomaculata) have a completely dormant period without
leaves. Some Alocasia species, especially those with
beautifully coloured foliage (e.g. A. lowii, A. sanderiana), can be difficult to grow and are only suitable
for “stove” conditions (high temperature, high humidity and shade). They also have a dormant period
during which they should be watered only very sparingly, while never being allowed to dry out
completely. Special attention must be given to the
plants during this critical period. When the shoot
starts into growth the plant should be repotted or
replanted in a mixture of sphagnum moss and peat as
used for Anthurium; chopped and partly decomposed
wood or bark chips can also be used in the mixture.
Alocasia macrorrhizos, A. odora and A. portei, on the
other hand, are evergreens with no resting period.
Propagation of Alocasia is by division of the stem,
from the tuber-like stolons or by seed.
True rheophytes like Aridarum, Bucephalandra,
Hottarum and Piptospatha are rather difficult to maintain
in cultivation because of their special requirements.
They are best grown in a mixture of sphagnum moss
and fibrous peat, if possible on rocks with a little humus;
they require high temperature and humidity.
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18 C O N S E R VAT I O N
The main threat to the long term survival of many
Araceae is the loss and reduction in quality of their natural habitats, especially in the rainforest regions of Asia,
the Malay Archipelago, Africa and tropical America.
Some Araceae are highly adapted to specific habitats and cannot survive in changed conditions; e.g.
Chlorospatha and rheophytic species of tribe
Schismatoglottideae. These taxa have proved difficult
to cultivate and are unlikely to survive in the long term
in botanic gardens. The same is also true of forest
aquatics such as Jasarum (from blackwater rivers) and
several species of Cryptocoryne.
Currently, not one species of Araceae is listed in
CITES (Convention on International Trade in
Endangered Species). Formerly Alocasia zebrina and A.
sanderiana from the Philippines were in Appendix 2.
The overcollection of Araceae for commercial trade
is unlikely to be a major cause of extinction, although
some Cryptocoryne species have been collected in
large quantities for the aquarium trade, much reducing
their natural populations. Removal of tropical forest,
however, eliminates most terrestrial, climbing and epiphytic species, many of which are shade-dependent.
Other habitats are also affected. In the case of the
aquatic genus Cryptocoryne, reduction in tree cover
results in faster flowing streams, which in turn gouge
out the stream bed and deposit sediment on the plants
along and near the banks. In such a situation the original plants soon die out. Fire is also very destructive,
both in its immediate effects and in favouring the invasion of weedy plants which prevent the regeneration
of the great majority of forest Araceae. Only a small
minority of species can establish themselves in secondary regrowth or in open areas, e.g. some of the
large species of Xanthosoma sect. Xanthosoma,
Alocasia, Typhonium blumei, Zantedeschia aethiopica
and certain races of Colocasia esculenta with a vigorous stoloniferous habit, which have become naturalized
widely in the tropics. Some species of Arum have
established themselves in parks and plantations, and
Cryptocoryne spiralis is a rice field weed. Arisaema
mooneyanum appears to have spread vigorously in
open highland fields in Ethiopia, although it was probably originally a forest edge species. These, however,
are exceptions; the great majority of Araceae disappear
along with the forest habitat.
Restricted endemic species are at particular risk.
The determining ecological or historical factors for
such narrow ranges remain completely unknown and
this makes the future prospects for such species bleak.
CONSERVATION
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19 F O S S I L R E C O R D
C
Gregor & Bogner (1984, 1989) have reviewed the fossil
record of Araceae and their papers should be consulted
for further details, particularly for the specialist literature.
No fossils are known earlier than the Eocene which
can definitely be ascribed to the Araceae, although
Spathiphyllum-like pollen has been described from the
Palaeocene and Limnobiophyllum scutatum from the
late Cretaceous (see below).
Fossils consisting of different parts of the plant
The genus Acorus (Acoraceae) is well documented
from the Miocene of Spitzbergen by the fossil A.
brachystachys, in which at least the leaf, inflorescence
axis and spadix are connected (Heer 1870). However,
the fossils from North America treated under this name
by Lesquereux (1878) belong to the Coniferae. Acorites
heeri (syn. Acorus heeri), from the Eocene of North
America, is also close to Acorus. The fossils of this
species consist of one single spadix and one spadix
with a piece of its inflorescence axis (Crepet 1978).
Kvaček (1995) has recently drawn attention to
Limnobiophyllum Krassilov, a fossil of extraordinary
interest in connection with the Araceae/Lemnaceae relationship. This fossil genus consists of free-floating,
stoloniferous plants with one or two suborbicular to
reniform leaves of different size, and simple as well as
branched roots on a reduced main axis. There are
(9)10–14 curved primary veins in the leaf blade, and
these join the margin or run into the apex. The second
order veins are reticulate between the primaries (higher
order venation is absent in Spirodela and Lemna). There
is no sign of the lateral pouches which occur in
Spirodela and Lemna but aerenchyma and pigment
cells are present. Two species are recognized:
Limnobiophyllum scutatum (Dawson) Krassilov and L.
expansum (Heer) Kvacek. Turion-like bodies are associated with L. scutatum. No seeds were found directly
connected to these fossils, but numerous, isolated,
ribbed seeds were associated with the same strata.
These seeds resemble those of Spirodela, Lemna and
similar fossil remains were described by Nikitin (1976)
as Lemnospermum pistiforme Nikitin from Siberia.
Generally, Limnobiophyllum most resembles Spirodela
but is larger and the branched roots are more like those
of Pistia. The fossils are less similar to Limnobium Rich.
(Hydrocharitaceae), a relationship suggested by some
authors. Limnobiophyllum scutatum is known from the
latest Cretaceous to the Oligocene of western North
America and the Palaeocene of east Asia.
Limnobiophyllum expansum is known from the
58
THE GENERA OF ARACEAE
Miocene of Europe. Limnobiophyllum may be considered as standing between Pistia (Araceae) and
Spirodela (Lemnaceae).
Leaf fossils
Leaf fossils from North America have been assigned
to the genera Peltandra, Philodendron and Pistia
while South America leaf fossils have been placed in
the genera Stenospermation (S. columbiense) and
Caladiosoma. Caladiosoma miocenica from the
Miocene of Trinidad belongs either to the genus
Caladium or to Xanthosoma (Berry 1925).
A North American Eocene leaf fossil with leaf venation typical of Peltandra was described by Hickey (1977)
as P. primaeva. A remarkably large fossil leaf, also from
the Eocene of North America, was described in great
detail by Dilcher & Daghlian (1977) as Philodendron
limnestis. However, Mayo (1991) suggested that the leaf
venation indicates that this fossil would be better placed
in the tribe Peltandreae, near Typhonodorum.
Two leaf remains from Sumatra were described by
R. Kräusel (1929): Araceophyllum engleri is probably
from the Pliocene and resembles Pothos, while
Araceophyllum tobleri is probably from the Upper
Miocene and belongs to the tribe Monstereae.
Two other species of Araceophyllum and the genus
Anthuriophyllum are leaf fossils which only doubtfully
belong to the Araceae. Weyland (1957) described
Anthuriophyllum spectabile based on cuticular analysis from Tertiary brown coal deposits along the lower
Rhine. More material showing the venation type is
required to confirm that it belongs to the Araceae. The
descriptions of Araceophyllum striatum (Weyland 1957)
and A. tarnocense (Rásky 1964) are too incomplete to
be accepted confidently as Araceae fossils.
Several leaf impressions of the genus Pistia (P.
claibornensis, P. corrugata, P. mazelii, P. nordenskiöldii,
P. wilcoxensis) have been described, but some are
not aroids at all, while others are only doubtfully so.
P. wilcoxensis Berry (1916), for instance, from the
Eocene of North America, has a venation type not
found in the Araceae and should be excluded altogether. Chondrophyllum nordenskiöldii was
transferred by Berry (1910) to Pistia but it represents
dicotyledonous leaves. Depape & Gauthier (1953)
described fossil leaves from the Eocene of Morocco
and suggested them to be close to extant Pistia stratiotes. They also gave a survey of reputed Pistia leaf
fossils, but none of these can be convincingly
assigned to this genus or to any other aroid genus.
1-22 Section A Acro 18/7/97 8:02 Page 59
Recently, three different leaf fossils have been
described from the Eocene of the Grube Messel
(Germany), although not formally named (Wilde 1989).
One belongs to tribe Colocasieae and another to tribe
Monstereae. The third resembles Aglaonema or
Homalomena (i.e. subfamily Philodendroideae in the
sense of Engler 1920b) in having a coriaceous leaf
blade with parallel-pinnate venation and laticifers.
Leaf-like fossils were described as Arisaema
cretacea (Lesquereux 1892) and as Arisaema dubia
(Hollick 1897) which were interpreted as portions of a
spathe, but both are very doubtfully araceous and are
best excluded from the family.
Fossil spadices and infructescences
Acoropsis eximia (syn. Carex eximia, Acoropsis
minor), from the Eocene Baltic Amber, represents a
well-preserved infructescence of the tribe Monstereae
(Bogner 1976c). This infructescence lacks tepals and
is therefore not related to Acorus as suggested by
Conwentz (1886). Fructus polyspermus from the
European Miocene could belong to the Araceae but
cannot be assigned with certainty to the family
(Engelhardt 1877). Crepet (1978) considered the
Eocene spadix Araceaeites fritelii from North America
to be too incomplete to be included in the Araceae
and the same must be said for the impressions of
Lysichiton washingtonensis from the Miocene of western North America (Berry 1931). Lysichiton nevadensis
is another impression from the Miocene of western
North America and could be araceous (MacGinitie
1933). An infructescence from the Cretaceous of eastern North America was described as Arisaema
mattewanense, but no internal structure was preserved
and so this fossil remains very doubtfully ascribed
(Hollick 1897). A spadix from the Miocene of North
America was described as Orontium fossile (Cockerell
1926). Araceaeites parisiense, from the Palaeocene of
France, was described as a spadix by Fritel (1910) and
was compared by him to Spathiphyllum, but it is very
incomplete and thus doubtful. Knowlton (1926)
described a very questionable infructescence from the
Miocene of North America as Arisaema hesperia.
Apart from Acoropsis, Acorites and Acorus brachystachys, all these fossil spadices or infructescences,
described under Araceaeites or an extant genus, are too
incomplete to be ascribed with confidence to the
Araceae and their taxonomic assignment must therefore remain highly dubious. Better preserved material
of these fossil taxa is needed to clarify their position.
Infructescences from the latest Eocene to earliest
Oligocene from Egypt described as Teichosperma
spadiciflorum (Renner 1907, Kräusel & Stromer 1924)
in the Pandanaceae and new material studied by
Tiffney & Wing (unpubl.) show that these fossils, with
their smooth reniform seeds, belong to the genus
Epipremnum of the Araceae (E. spadiciflorum).
Fossil fruits and seeds
Nikitin described Acorus procalamus based on fruits
and seeds from Quaternary deposits in the former
Soviet Union and this has been well illustrated by Katz
et al. (1965). Fossil seeds of Calla palustris and Acorus
calamus are also described by Katz et al. (1965), while
seeds typical of Pistia were described by Dorofeev
(1963) as P. sibirica from the Oligocene of Siberia.
Among the best-known aroid fossils are seeds of
Monstereae and Lasioideae described from European
brown coal deposits of Oligocene, Miocene and
Pliocene age. These were formerly considered to
belong to Epipremnum, but are today included within
three genera: Epipremnites (type: E. ornatus) and
Scindapsites (type: S. crassus) of tribe Monstereae, and
Urospathites (type: U. dalgasii) of subfamily Lasioideae
(Gregor & Bogner 1984, 1989). Keratosperma, with the
single species K. allenbyense, is an Eocene fossil seed
from Canada and belongs to the Lasioideae (CevallosFerriz & Stockey 1988).
Scindapsites has reniform seeds with a smooth testa
of variable thickness covered with scattered foveolae.
There are distinctive outgrowths on each side of the
raphe which are sometimes partly coherent.
Epipremnites has curved seeds with the foveolae
arranged in rows on an otherwise smooth testa; no
outgrowths are present on the raphe. Urospathites has
somewhat curved seeds and the testa is warty, spinose
or tuberculate.
Fossil pollen
Some fossil monosulcate pollen grains have been
compared with Araceae, but this pollen type also
occurs in many other families of monocots and dicots
and these fossils cannot be accepted as araceous in the
absence of associated floral remains.
Mtchedlishvili and Shakhmundes (1973) described
the pollen of four species in a new genus, Jugella (type:
Jugella sibirica) from the Lower Cretaceous of the former Soviet Union. The authors compared them to
Spathiphyllum pollen because of their striate exine, but
Spathiphyllum has inaperturate pollen grains whereas
in Jugella they are monocolpate which suggests that this
genus should be excluded from the Araceae.
Wodehouse (1933) described North American
pollen from the Eocene as Peltandripites davisii and
compared it with Peltandra, describing it as “...without
germinal furrows or pores...”. However, his rough
drawing shows something like a furrow and since the
pollen of Peltandra is inaperturate this argument seems
doubtful. Peltandripites dubius probably belongs to
the Asteraceae (Sah & Dutta 1966, Thanikaimoni 1969).
Biswas (1962) described fossil pollen from the
Eocene of Assam as Colocasioideaepites, but these
probably represent palm pollen grains (Nypa type).
Monsteroideaepites eospathiphyllum is inadequately
FOSSIL RECORD
59
1-22 Section A Acro 18/7/97 8:02 Page 60
described and figured and is therefore only doubtfully
araceous (Muller 1981).
Inaperturate pollen grains with a striate exine were
reported by Graham (1976) from the Miocene of
Veracruz, Mexico and assigned to Spathiphyllum. This
is probably correct because other genera of Araceae
with the same pollen type do not occur in Mexico.
Pollen similar to that of Spathiphyllum was described
from the Palaeocene of Colombia by Hammen & Garcia
de Mutis (1966) as Ephedripites vanegensis.
Pollenites tranquillus from the Eocene was compared with Acorus (Potonie 1934) and was later
transferred to the form-genus Monocolpopollenites as M.
tranquillus by Thomson & Pflug (1953); this pollen
probably belongs to the Arecaceae (Nichols, Ames &
Traverse 1973).
Fossils excluded from the Araceae
Aracispermum Nikitin (type: A. canaliculatum), a
seed fossil, may confidently be excluded from the
Araceae, because it is characterized by a very large
micropylar aperture, probably the site of an aril. All
aroid seeds known have only a very small micropyle.
Gregor & Bogner (unpubl.) and Mai (1995) consider
that the seeds of Aracispermum canaliculatum and
related species belong to the Zingiberaceae.
Aracispermum johnstrupii belongs to the dicot genus
Myrica (Myricaceae, Kirchheimer 1957). Aracispermum
jugatum was transferred by Mai to Caricoidea
(Cyperaceae) as C. jugata (Mai & Walther 1978, see also
Friis 1985). Aracispermum hippuriformis was considered by Mai (in Mai & Walther 1978) as closely related
to the genus Alpinia (Zingiberaceae).
The fossil “strobilus” of Aracistrobus dravertii is in
fact an old infructescence of Platanus (Platanaceae),
showing the scars where the fruits were previously situated (Gregor & Bogner 1989). The “strobilus” remains
of Araceites hungaricus are impressions of the shoot
tips of a species of Pinus in which the needles are
missing (Gregor & Bogner 1989).
The fruits and seeds of Campylospermum hordwellensis (syn. Cyrtospermites hordwellensis) belong to
the genus Visnea (Theaceae), according to Mai (1971).
The monocotyledonous infructescence Viracarpon
hexasper mum from the early Eocene Deccan
Intertrappean beds of India has been critically reinvestigated by Bande & Awasthi (1986), based on new
well preserved material, and a new reconstruction
made. Four species of the genus Viracarpon (including Shuklanthus) have been described but only two
(V. hexaspermum and V. elongatum) should be recognized (after Bande & Awasthi 1986). A relationship
with Araceae, Cyclanthaceae and Pandanaceae has
been suggested by various authors. New studies show
that these fossils do not belong to the Araceae or
Cyclanthaceae and also that they cannot be included
in the Pandanaceae (B.C. Stone pers. comm.).
60
THE GENERA OF ARACEAE
Perhaps Viracarpon represents a genus of an extinct
family. However, it would be helpful if its as yet
unknown vegetative parts were found. The fruits of V.
hexaspermum are sessile on an unbranched axis and
are bractless. The fruit is hexangular with six locules
around a central core which is slightly longer than
the locules. Each locule contains a single seed. The
outer wall of the ovary extends upwards in six perianth-like lobes, forming a cup-like structure
(interpretation by Bande & Awasthi, but questionable)
free at the apex and connate below with a vertical
ridge running the entire length of the middle of the
inner surface of each lobe. The inside of the lobes are
densely covered with long hairs. The peduncle has
monocotyledonous bundles.
Porosia verrucosa (Hickey 1977) of the North
American Late Cretaceous and Palaeocene has thick,
reniform leaves and has been compared to Araceae,
Lemnaceae and Hydrocharitaceae ; more complete
material is necessary to resolve its relationships (Gregor
& Bogner 1989, Crane et al. 1990, Kvaček 1995).
Fossil flowers, probably of Eocene age, have been
described from the Indian Deccan Intertrappean series
as Sahnipushpam shuklai (syn. Sahnipushpam glandulosum) and were assigned to the Araceae by Prakash
& Jain (1964). However, following further examination
of the original material, Gregor & Bogner (1989) have
excluded this fossil from the Araceae. The flowers were
always single and abscissed individually (unknown in
Araceae). The pollen and the structure of the ovary
locules and style are different from those found in
Araceae. Although the true taxonomic position of
Sahnipushpam is still unclear, it may nevertheless be
excluded from the Araceae without reservation.
Ettinghausen (1870) described a fossil aerial root
from the Miocene of Croatia as Aronium extinctum
and compared it with Anthurium, but this fossil is best
regarded as “incertae sedis”.
Cyclanthodendron sahnii from the Deccan
Intertrappean beds, considered to be of early Eocene
age, was first described as Palmoxylon sahnii. Later a
separate genus, Cyclanthodendron, was established,
mainly on the basis of the compound vascular bundles
(absent in Arecaceae) and assigned to the
Cyclanthaceae. This fossil has also been compared
with the Pandanaceae and Araceae, in which compound bundles were observed by French & Tomlinson
(1986). New material from the same locality showed
that this fossil is very close to the Strelitziaceae (Biradar
& Bonde 1990).
Some other fossils which have been thought to
belong to the Araceae have been transferred in previous palaeobotanical literature to other families: Arecites
trabucci (Arecaceae), Aronites dubius (Coniferae, partly
indeterminable), Aroites tallyanus (Coniferae), Pistites
loriformis (Cycadaceae), Aroides stutterdii (Stichoporella
in the Dasycladaceae), Pothocites grantonii (Calamites
s.l. in the Calamariaceae). Aroides crassispatha is a
very doubtfully assigned fossil from the Permian.
C
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C
20 P H Y L O G E N E T I C R E L AT I O N S H I P S W I T H I N
T H E M O N O C OT Y L E D O N S
The phylogenetic relationships of Araceae to other
monocots have never been clear. The fossil record provides no clues and we have to rely on the comparative
study of modern taxa.
Some influential earlier authorities, such as Engler &
Gilg (1919) and Wettstein (1935), grouped the Araceae
together with the Arecaceae and Cyclanthaceae. This
view was based on the common tendency in these families to floral reduction, “spathe” development, the
condensation of the inflorescence into one or several
spadices and an associated tendency to pseudanthial
inflorescences. For similar reasons, the Araceae have
also been associated in the past with Pandanaceae and
Typhales. The link with Typhales was also suggested
because it had been observed that Sparganium
(Sparganiaceae) and Acorus (Acoraceae) are infected by
the same rust, Uromyces sparganii. Whether there is a
close phylogenetic relationship between Acorus and
Sparganium remains unclear, but since Grayum’s (1987)
widely accepted removal of Acorus from the Araceae,
the case for an Araceae-Typhales relationship has been
seriously, if not fatally, weakened. As regards the
Arecaceae, Cyclanthaceae and Pandanaceae, their floral and vegetative structure differ so strikingly from the
Araceae that any resemblances must surely be due to
parallel evolution rather than sister group relationship.
The Dioscoreales (in the sense of Dahlgren et al.
1985, consisting of Dioscoreaceae, Petermanniaceae,
Smilacaceae, Stemonaceae, Taccaceae, Trichopodaceae,
Trilliaceae) is a group sometimes linked to the Araceae
because of a superficial similarity in leaf form and
venation. The differences, however, are also impressive. The Dioscoreales differ from the Araceae in the
usually twining habit, different type of reticulate venation (with numerous densely arranged, scalariform
cross veins connecting the major veins), inferior
ovaries, usually winged, capsular fruit and usually
winged seeds. Furthermore, the Dioscoreales seem
unlikely to be monophyletic, which further complicates an assessment of their relationship to the Araceae.
The concept of an origin from a common ancestor
of the Liliiflorae (sensu Dahlgren et al. 1985), or even
from within this taxon has been widely held (e.g. Hallier
1912, Bessey 1915, Hutchinson 1934, 1959, Novak 1954,
Kimura 1956, Takhtajan 1959). Hutchinson (1934) went
so far as to suggest that the Araceae could be derived
directly “... from the stock of the tribe Aspidistreae of
Liliaceae in which the flowers are arranged in dense
spikes (Tupistra, Rohdea, Gonioscypha).” This latter
similarity must surely be, however, the result of parallel evolution. Lying behind the Liliiflorean origin
hypothesis was the very general view that this group
represents the “type” or “Bauplan” of the monocots, or
to put it another way, that the Liliiflorae has a basal
phylogenetic position within the monocots as a whole.
Engler (1920b) recognized clear evidence of the
“monocot type” in the floral structure of some genera
of Araceae (e.g. tribe Potheae) and consequently he
considered these to be primitive aroids. He even stated
that his subfamily Pothoideae differed from the
Liliaceae essentially only in having a fleshy outer seed
integument. In his classification however, Engler (e.g.
Engler & Gilg 1919) did not associate Araceae and
Liliaceae closely and it is reasonable to suppose that he
saw the similarities between them in terms of shared
primitive characters (plesiomorphies); i.e. Araceae must
have arisen by independent evolution from primitive
monocot forms.
Characters which may be considered primitive in
Araceae by outgroup comparison to Liliiflorae are:
absence of laticifers, inconspicuous spathe, bisexual
flowers with a perigone of two whorls of 3 free tepals
and two whorls of 3 free stamens, basifixed anthers on
more-or-less elongated filaments, thecae dehiscing by
longitudinal slit, monosulcate pollen, syncarpous, 3-locular, superior ovary, several anatropous ovules per
ovary locule, axile placentation, and presence of
endosperm in the mature seed. However, many of
these characters can be regarded as primitive in
Araceae by comparison with the monocots as a whole,
which weakens the concept of Liliiflorae as a sister
group for the Araceae.
A further problem is that the Liliiflorae are almost
certainly paraphyletic or polyphyletic. Recent molecular studies (e.g. Duvall et al. 1993, Chase et al. 1995)
have placed the genus Pleea (Melanthiaceae) near the
base of the monocot clade, together with the Araceae,
Alismatiflorae and Acorus. These studies also indicated
that Lemnaceae belong within the Araceae, a result
recently further supported by a comprehensive analysis of cpDNA characters of Araceae and Lemnaceae
(French et al. 1995).
In the following discussion, therefore, the possible
sister group relationships of the Araceae are considered
only in relation to the Acoraceae, the Alismatiflorae
and the Lemnaceae, together with an overview of the
proposed primitive character states of Araceae.
Relationships with the Acoraceae
Acorus has long been considered a member of
Araceae, but recently Grayum (1987, 1990) has presented a convincing case for its removal to a separate
P H Y L O G E N E T I C R E L AT I O N S H I P S W I T H I N T H E M O N O C OT Y L E D O N S
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family, a view which has been widely accepted. The
long list of significant characters by which Acoraceae
and Araceae are distinguished (Table 3) also strongly
suggests that they are not even sister taxa.
Table 4. Proposed synapomorphies and
plesiomorphies of the Araceae.
POSSIBLE SYNAPOMORPHIES
• Lack of vessels in stems and leaves (stem vessels
of climbing Araceae derived?)
Table 3. Characters separating Acoraceae from
Araceae.
• Presence of tannins
• Ethereal oil cells
• Distichous leaves
• Lack of raphides
• Presence of spathe
• Unifacial ensiform leaves
• Presence of spadix
• Unique pattern of bud trace insertion
• Flowers lacking floral bracts
• Separate vascular systems in peduncle
• Protogyny
• Introrse anthers (in Araceae known only in
Zamioculcas)
• Anthers extrorse
• Stellate endothecial thickenings
• Tapetum periplasmodial
• Tapetal cells with 2–4 nuclei
• Tapetal cells 1-nucleate
• Secretory anther tapetum
• Placentation basal (equivocal)
• Exclusively axile vascular supply to placentae
• Location and structure of ovular trichomes
• Helobial endosperm development with cellular
development in micropylar chamber
• Presence of perisperm
• Embryogeny caryophyllad or solanad
• Dicot-type cellular endosperm development
• Berries (dehiscent in Lagenandra)
• P2cs sieve tube plastids
• Pollen 2-nucleate when shed
• Lack of endosperm (equivocal)
The presence of ethereal oil cells, absence of
raphides, presence of secretory anther tapetum, presence of perisperm and dicot-like cellular endosperm
development are characters which could suggest a
link to monocot-like dicot families such as Piperaceae
and Aristolochiaceae. The molecular studies of Duvall
et al. (1993) and Chase et al. (1995) now indicate that
Acorus could be considered the most primitive living
monocot taxon.
POSSIBLE PLESIOMORPHIES
• Presence of raphides
• Absence of silica
• Absence of tricin
• Absence of ethereal oils
• Absence of laticifers
• Leaves bifacial with petiole and lamina
• Flowers actinomorphic
• Tepals 4–6 in two whorls of 2 or 3
Primitive characters of the Araceae
• Anthers basifixed
• Stamen filaments ± elongate
The removal of Acorus from Araceae has made it
easier to reassess the hypothetical primitive character set
for the family. The basic evolutionary trend within
Araceae has always been viewed as the evolution of unisexual flowers in monoecious pseudanthoid
inflorescences from simpler inflorescences with bisexual
flowers and a lesser degree of pseudanthial development. This hypothesis is supported by our cladistic study
(Mayo et al., in prep.). Once this trend is accepted, the
evolutionary polarity of certain other important characters can be defined by correlation. Thus most bisexual
genera lack laticifers and have aperturate pollen. Based
on our cladistic analyses and a reassessment of some
other characters not used in our analysis but discussed
by Dahlgren and colleagues (Dahlgren & Clifford 1982,
Dahlgren et al. 1985), the primitive character states
shown in Table 4 are proposed (see Grayum 1990 for a
similar but not identical list).
62
THE GENERA OF ARACEAE
• Pollen mother cell cytokinesis successive
• Pollen monosulcate (or at least aperturate)
• Ovary syncarpous
• Ovary superior
• Ovules crassinucellate
• Perisperm absent
Relationships with Alismatiflorae
Dahlgren and co-workers (Dahlgren & Clifford 1982,
Dahlgren & Rasmussen 1983, Dahlgren, Clifford & Yeo
1985) argued strongly for a sister relationship of
Ariflorae (Araceae, Lemnaceae) to Alismatiflorae, pointing out many important differences between Araceae
and Arecaceae. Grayum (1984, 1990, 1991b, 1992a)
1-22 Section A Acro 18/7/97 8:02 Page 63
agreed with Dahlgren’s views; his re-interpretation of
araceous endosperm development as helobial further
emphasized a relationship with Alismatiflorae.
The characters that link Alismatiflorae to Araceae,
based on our assessments of primitive character states
in Araceae, are given in Table 5.
Among the clearest of these are periplasmodial
tapetum, 1-nucleate tapetal cells and caryophyllad
embryogeny, but data for these are based on a very
patchy coverage of the two taxa. Many of the other
characters could be interpreted as plesiomorphies for
the monocots as a whole.
Table 5. Proposed synapomorphies (or plesiomorphies) of the Alismatiflorae and Araceae.
Certain other characters adduced by Dahlgren et al.
(1985) to support the Alismatiflorean link must be ruled
out in the light of our cladistic study, since they emerge
as derived within Araceae – presence of intravaginal
squamules, presence of laticifers and presence of 3nucleate pollen grains.
The sister group relationship with Alismatiflorae
remains equivocal on this evidence but is a hypothesis which continues to merit serious consideration, and
appears stronger than any other yet proposed. The
molecular studies of Duvall et al. (1993) and Chase et
al. (1995) are not completely consistent in grouping
Araceae and Alismatiflorae together, but as with the
morphological and anatomical data, it also remains
one of the strongest available hypotheses based on
molecular evidence.
• Vessels lacking in stems and leaves (stem vessels
probably derived in climbing Araceae)
Relationships with Lemnaceae
• Leaves distichous (primitive in Araceae, present in
Scheuchzeriaceae, Potamogetonaceae)
The most widely accepted sister group relationship
of Araceae is that with the Lemnaceae, but this is by no
means universally accepted and has been strongly challenged recently by Grayum (1984, 1990, 1991b, 1992a).
The Lemnaceae are considered by most authors to
be at least closely related to Araceae, and to have
evolved from them by neotenous reduction of leaf and
inflorescence. This view is based, among other characters, on the similarity between seedlings of Pistia and
Spirodela, embryological characters (Maheshwari 1956,
1958, Maheshwari & Khanna 1956) and the putative
homology between the aroid spathe and the “spathe”
of Spirodela and Lemna. Other similarities adduced are
the presence of grooved raphides and operculate seeds
in Pistia and Lemnaceae. An important difference, however, is that the pollen of Lemnaceae is ulcerate and
spinose while in Pistia it is inaperturate and plicate (or
± striate); ulcerate pollen is unknown in Araceae (for
Limnobiophyllum see chapter 19).
The three hypotheses considered in more detail here
are shown in Figure 9. This illustrates the need to assess
possible synapomorphies (shown as thicker lines) for
the following sister group pairs: Lemnaceae-Araceae,
Lemnaceae-Pistia, and Lemnaceae-monoecious Araceae.
A fourth possibility is a trichotomous monophyletic group
composed of Lemnaceae-Araceae- Alismatiflorae. In the
following discussion, character states in Spirodela are
regarded as representing the primitive condition in
Lemnaceae.
• Petiolate and laminar leaves with sheathing base
(also in Liliiflorae)
• Presence of spadix (Aponogetonaceae,
Juncaginaceae, Potamogetonaceae, Zosteraceae)
• Stamen filaments distinct (plesiomorphy in
monocots)
• Anthers terminal (plesiomorphy in monocots)
• Anthers extrorse (also in Liliiflorae, doubtful in
Lemnaceae)
• Tapetum periplasmodial (unusual in monocots)
• Tapetal cells 1-nucleate (unusual in monocots)
• Ovules several per locule (plesiomorphy in monocots?)
• Ovules anatropous (plesiomorphy in monocots)
• Placentation basal (equivocal as primitive state in
Araceae)
• Ovule with nucellar cap (occurs elsewhere in
monocots)
• Embryo sac of Polygonum type (plesiomorphy in
monocots)
• Endosperm development with helobial type of chalazal chamber (helobial endosperm development
occurs elsewhere in monocots, e.g. Liliiflorae)
• Embryogeny of caryophyllad type (onagrad and
asterad types commonest in monocots)
• ?Embryo chlorophyllous (data scarce)
• ?Endosperm absent (equivocal as primitive state in
Araceae)
Lemnaceae-Araceae as sister groups
• ?Unique type of seedling development (linked to
previous character; a similarity between
Scheuchzeriaceae, Aponogetonaceae and Araceae
with endospermless seeds; equivocal as primitive
state in Araceae)
Possible synapomorphies are listed in Table 6. The
strongest of these characters is that of endosperm
development, which typically combines cellular development in the micropylar chamber with a haustorial
chalazal chamber containing a single hypertrophied
nucleus (Grayum 1991b).
P H Y L O G E N E T I C R E L AT I O N S H I P S W I T H I N T H E M O N O C OT Y L E D O N S
63
1-22 Section A Acro 18/7/97 8:02 Page 64
Lemnaceae
Table 7. Possible synapomorphies of the
Lemnaceae and monoecious Araceae.
Araceae
• Flowers unisexual (controversial interpretation in
Lemnaceae)
Alismatiflorae
• Pollen 3-nucleate
• Exine spinose (but pollen aperturate and ulcerate
in Lemnaceae)
Lemnaceae
• Asterad embryogeny (primitively caryophyllad in
Araceae and Alismatiflorae)
monoecious Araceae
• Endosperm starchy (no endosperm in
Alismatiflorae)
other Araceae
• Base chromosome number x=10 (this number
occurs in monoecious Araceae but not in more
primitive bisexual genera)
Alismatiflorae
Lemnaceae
Pistia
other Araceae
Figure 9. Alternative sister groups of the Lemnaceae
Table 6. Possible synapomorphies of the
Lemnaceae and Araceae.
• Flavonols present (rare in Alismatiflorae, absent
in Pistia)
• Raphides present (widespread in monocots,
absent in Alismatiflorae and monocot-like dicots)
• Spathe present (controversial interpretation in
Lemnaceae, bract subtending inflorescence
widespread in monocots)
• Outer integument overtopping inner (?distribution in other monocots)
• Ovary syncarpous (controversial interpretation
in Lemnaceae, possible symplesiomorphy with
Liliiflorae)
• Helobial endosperm development with cellular
development in micropylar chamber (unique in
monocots)
• Endosperm present in ripe seeds (possibly
derived in Araceae, general in monocots)
Lemnaceae-monoecious Araceae as sister groups
Possible synapomorphies, additional to those linking Lemnaceae to Araceae as a whole, are listed in
Table 7.
A number of lemnaceous characters which do not
fit with primitive Araceae agree better with the
64
THE GENERA OF ARACEAE
advanced subfamily Aroideae. Unisexual flowers, 3nucleate and spinose pollen and asterad embryogeny
are all more characteristic of advanced rather than
primitive Araceae. A base chromosome number of
x=10 occurs in monoecious Araceae but not in primitive ones. However the aperturate pollen of
Lemnaceae is ulcerate and this type is unknown in
Araceae. Almost all monoecious Araceae have inaperturate pollen and so this character is problematic were
Lemnaceae to be inserted well within the monoecious
aroid clade (subfamily Aroideae). In a sister group
relationship, however, there is less difficulty. The tribe
Zamioculcadeae, which is basal in subfamily Aroideae,
has aperturate pollen (and so, occasionally, does tribe
Stylochaetoneae – also near basal), and so a position
for Lemnaceae near the base of the Aroideae clade is
at least conceivable. The molecular data, on the other
hand, suggests that Lemnaceae are embedded well
within the Aroideae clade (French et al. 1995). On this
hypothesis, some further explanation will be required
for the evolution of the pollen characters.
Lemnaceae-Pistia as sister groups
The major character conflicts and the possible
synapomorphies of these two taxa are shown in Table 8.
The six character differences are a major obstacle to
linking Lemnaceae and Pistia in a sister group relationship, particularly the pollen and nucellar characters.
The latter is also problematic in grouping Lemnaceae
within Araceae since although few genera of Araceae
have been studied, none are yet known certainly to
have crassinucellate ovules.
On the other hand, the joint possession of operculate seeds and practically identical seedling
development appear to be strong evidence for a close
relationship. It is nevertheless tempting to regard these
as convergences resulting from their highly specialized niche as floating aquatics. The molecular studies
1-22 Section A Acro 18/7/97 8:02 Page 65
of French et al. (1995) place the two taxa in widely separate positions within subfamily Aroideae (as defined
in our classification). This hypothesis of sister group
relationship thus remains very doubtful.
The Lemnaceae are best considered for the present as a derived offshoot of Araceae with a sister
group relationship to the major advanced clade represented by subfamily Aroideae. There is a great need for
more comparative embryological studies of Araceae
which could help to shed further light on this problem.
Are the Araceae paraphyletic?
The weight of evidence, especially the new data
from molecular studies, now strongly favours the
inclusion of Lemnaceae within Araceae as merely
one subclade of an overall monophyletic group. We
have not, however, included Lemnaceae in our classification nor in our taxonomic treatment. Our
reasons are pragmatic. The molecular evidence
emerged at a very late stage in the preparation of this
book. In addition, Landolt (1986) and Landolt &
Kandeler (1987) have provided a recent comprehensive taxonomic treatment of Lemnaceae which we
certainly could not improve upon.
It would also be desirable to carry out a combined
analysis of molecular and morphological data to
establish the position of Lemnaceae more precisely
within Araceae. With these qualifications in mind it is
nonetheless important to emphasize that the family
Araceae is almost certainly paraphyletic, while the
order Arales (Araceae including Lemnaceae) is very
probably monophyletic.
Table 8. Character conflicts and possible synapomorphies of the Lemnaceae and Pistia.
CHARACTER CONFLICTS
Lemnaceae
• Stamens free
• Pollen ulcerate
• Ovules crassinucellate
• Exine spinose
• Apiose present
• Tannins absent
•
•
•
•
•
•
Pistia
Stamens connate
Pollen inaperturate
Ovules tenuinucellate
Exine plicate
Apiose absent
Tannins present
POSSIBLE SYNAPOMORPHIES
• Grooved raphides
• Floating aquatic (rare in monocots)
• Stolons arising in lateral pouch
• Operculate seeds (also in Commelinales and
Zingiberales)
• Seedling development: median cotyledonar
lobe, no primary root, operculum persistent
over root pole, first adventitious roots arising
around root pole.
• Fruit not a berry
• Laticifers absent
• Root hairs absent
P H Y L O G E N E T I C R E L AT I O N S H I P S W I T H I N T H E M O N O C OT Y L E D O N S
C
65
1-22 Section A Acro 18/7/97 8:02 Page 66
21 P H Y L O G E N E T I C R E L AT I O N S H I P S W I T H I N A R A C E A E
C
Previous work on the classification of Araceae has
reached a reasonable consensus on the circumscription of the tribes and subtribes. The major difficulties
revolve around the subfamily concepts. These were
introduced by Engler (1876b) and have been found
very useful by subsequent authors. It is much easier
to think taxonomically in terms of 8 subfamilies
rather than 30 tribes. The reluctance of modern
authors to abandon the subfamily concept, despite
the obviously superior taxonomic quality of the tribal
groups, is shown by their constant use in aroid literature. A stage has now been reached in which
confusion abounds. Current classifications (Grayum
1990, Bogner & Nicolson 1991, Hay & Mabberley
1991) differ radically in the composition of several
subfamilies and it is no longer possible to speak, for
example, of subfamilies Aroideae, Lasioideae or
Philodendroideae without citing the author of the
system being used.
We therefore carried out a series of cladistic analyses using all genera as terminal taxa, and without
assuming any higher groupings at the outset. Our
classification (chapter 23) is based on the results.
The details of these analyses will be given in a separate publication (Mayo et al., in prep.). The purpose
of this chapter is to explain the phylogenetic basis of
the classification we have adopted. The cladistic
study used 63 morphological and anatomical characters and 109 taxa (including 3 outgroups). The
character data was gleaned from the literature, our
own studies of herbarium, spirit and living material
and from unpublished observations generously supplied by various colleagues (see acknowledgements).
The main outgroups used were Tofieldia
(Melanthiaceae-Liliiflorae) and Scheuchzeria
(Scheuchzeriaceae-Alismatiflorae), representing
Liliiflorean versus Alismatiflorean sister group relationships respectively. Figure 2 shows one of the 100
equally parsimonious trees found in an analysis using
Tofieldia as the outgroup.
In producing a classification from the cladistic
results we have taken the view that groups which
emerged consistently from the analysis should be
considered seriously as named taxa in the classification. In cases where traditionally recognized groups
failed to emerge in the cladogram it was necessary to
decide whether this was a sufficient reason to reject
them in the classification. In the case of tribe
Zomicarpeae, for example, we have recognized the
tribe despite the fact that it usually failed to emerge
as a monophyletic group. We justify this because
they possess some “good” characters in common (e.g.
66
THE GENERA OF ARACEAE
anastomosing laticifers, female zone of spadix fused
to spathe, etc.) and especially because this taxon
emerged as a monophyletic group in the molecular
analysis of French et al. (1995). In contrast, no support was found for the concept of subfamily
Philodendroideae in the sense of Engler (1920b),
Grayum (1990) or Bogner & Nicolson (1991).
Most currently accepted tribal and subtribal groups
stood up well to analysis, thus confirming the prevailing view of aroid taxonomists that they are mostly
monophyletic (or natural) groups. The tribal groups
held together even when chromosome base number,
generally considered an important tribal character, was
excluded from the analysis.
The results of a comprehensive cpDNA study by
French et al. (1995) give a strikingly similar result to
ours in the basic structure of the cladogram. We
have therefore incorporated into our classification
the strongest features of these two independent
analyses and we have not hesitated to modify our
major taxon concepts in the light of their results.
We hope this will help to achieve long term stability
in aroid classification.
With few exceptions, the suprageneric groups recognized and named in our classification represent
monophyletic taxon concepts resulting from the cladistic analyses. We have deliberately chosen not to
overemphasize the internal topologies of these clades,
preferring to concentrate on the “main skeleton”. New
studies and analyses will be needed to give a more reliable picture of the internal phylogeny of the various
tribes and subfamilies recognized here.
Figure 11 shows the cladistic relationships of the
seven subfamilies we recognize, based on a consensus
tree of 100 equally parsimonious trees, one of which
is shown in Figure 10.
A. Major Group Proto-Araceae
This clade consists of subfamilies Gymnostachydoideae and Orontioideae and is defined by the
following characters – medium sized pollen, condensed,
non corm-like thickened stem, subterranean stem, usually unilocular ovaries and locules with 1–2 ovules.
These are rather weak and highly homoplasious
synapomorphies, which suggests that the group may
be paraphyletic rather than monophyletic. It is noteworthy, however, that French et al. (1995)
independently and consistently found the same group
using cpDNA data.
1-22 Section A Acro 18/7/97 8:02 Page 67
1. Subfamily Gymnostachydoideae
Among other peculiar characters, Gymnostachys
has linear leaves with parallel venation and a flowering shoot of unique structure. We therefore prefer to
keep it in its own monospecific subfamily (following
Bogner & Nicolson 1991).
clade. The tribe Spathiphylleae failed to group consistently with these three tribes but does so in the cpDNA
analysis of French et al. (1995). Our subfamily
Monsteroideae thus differs from Engler’s only by the
addition of Anadendrum and Heteropsis.
5. Subfamily Lasioideae
2. Subfamily Orontioideae
This group corresponds to tribe Orontieae of previous classifications. The synapomorphies are:– leaf
blade expanded not linear, anatropous or hemianatropous ovules, endosperm sparse to absent, base
chromosome number x=13.
B. Major Group True Araceae
This is a previously unrecognized group and is supported by the following synapomorphies:–
conspicuous or flag-like spathe, major internode of
inflorescence between spathe and next leaf below,
continuation shoot in axil of penultimate leaf before
spathe, leaf blade expanded not linear, basal or nearbasal placentation. These characters are strong and
less homoplasious which suggests that the group is
indeed very probably monophyletic.
3. Subfamily Pothoideae
Tribe Potheae is a consistent group defined by the
following synapomorphies:– monopodial shoot architecture, lack of endosperm, chromosome base number
x=12. The genus Anthurium failed to group consistently either with tribe Potheae or any other group in
our analysis. French et al. (1995), however, found that
Anthurium consistently grouped with tribe Potheae
and we have adopted this to form the subfamily
Pothoideae. Figure 10 is an example of one family of
cladograms which show the two taxa as sister groups,
and in this case they share a single synapomorphy –
fine leaf venation with secondary and tertiary veins
forming mostly cross veins to primaries; the plesiomorphic condition in Anthurium was assumed to
be that shown in Anthurium sect. Digitinervium.
4. Subfamily Monsteroideae
In our analysis the genera of the tribes Monstereae,
Heteropsideae and Anadendreae form a single consistent clade. The synapomorphies are:– spathe
undifferentiated into tube and lamina and soon deciduous or marcescent with distinct basal abscission,
perigone connate. The latter character occurs only in
Anadendrum, the perigone being lost further up the
Our subfamily Lasioideae corresponds to tribe
Lasieae of earlier systems and is a very stable and consistent clade.
The synapomorphies are:– monosulcate pollen
(derived by reversal from the inaperturate state),
absence of pollen starch, basal ribs of primary veins
very well developed, dracontioid leaf margin development, spadix with basipetal flowering sequence,
anthers dehiscing by oblique pore-like slits and very
often unilocular ovaries.
Monosulcate pollen is normally regarded as primitive in the family and it is possible that its occurrence
as a reversal here may be an artefact contingent on the
topology of this particular cladogram (see discussion
under subfamily Aroideae).
6. Subfamily Calloideae
The genus Calla consistently emerges as a single
clade and was usually among the basal branches in our
analysis. French et al. (1995) also found that Calla
emerged consistently as an independent clade, but in
their analysis it occurred further up the tree. The
autapomorphies are:– perigone absent, pollen diaperturate, pollen globose, laticifers simple, petiole sheath
long-ligulate, ovary unilocular, chromosome base number x=18. Calla seems to be highly autapomorphic
and its sister relationships remain obscure.
7. Subfamily Aroideae
The most striking feature of the analysis is the large
clade which contains all the monoecious genera. This
group corresponds to Schott’s “Diclines” (Schott 1860)
and is not recognized in the classifications of Engler
(1876b, 1920b), Grayum (1990), Bogner & Nicolson
(1991) and Hay & Mabberley (1991), which all embody
the idea that monoeicy and associated advanced spathe
and spadix characters must have evolved several times
from bisexual-flowered ancestors.
Strong support for our concept comes from the
DNA work of French et al. (1995) which also produces a single clade for all monoecious taxa. On the
basis of both studies, we therefore feel confident in
advocating the taxonomic recognition of this group as
subfamily Aroideae since it represents a major
advance and simplification in our understanding of
aroid phylogeny.
PHYLOGENETIC RELATIONSHIPS WITHIN ARACEAE
67
1-22 Section A Acro 18/7/97 8:02 Page 68
Tofieldia
ACORACEAE
GYMNOSTACHYDOIDEAE
ORONTIOIDEAE
CALLOIDEAE
ANTHURIEAE
POTHEAE
SPATHIPHYLLEAE
ANADENDREAE
HETEROPSIDEAE
MONSTEREAE
LASIOIDEAE
ZAMIOCULCADEAE
STYLOCHAETONEAE
SPATHICARPEAE
Dieffenbachia
AGLAONEMATEAE
ZANTEDESCHIEAE
PHILODENDREAE
HOMALOMENEAE
ANUBIADEAE
Bognera
Figure 10. Cladogram of the genera of Araceae. One of 100 equally parsimonious trees (Mayo et al., in prep.). Terminal taxa are shown as
subfamilies or tribes when monogeneric or when all genera emerged consistently as a single clade. Generic names are given where the
genera of recognised tribes failed to form monophyletic groups in the analysis (see chapter 23 for a full synopsis of the classification).
68
THE GENERA OF ARACEAE
1-22 Section A Acro 18/7/97 8:02 Page 69
MONTRICHARDIEAE
CULCASIEAE
THOMSONIEAE
NEPHTHYTIDEAE
CALLOPSIDEAE
Zomicarpella
Ulearum
AROPHYTEAE
ARISAREAE
AMBROSINEAE
PISTIEAE
Filarum
Pinellia
Zomicarpa
Arisaema
AREAE
CRYPTOCORYNEAE
SCHISMATOGLOTTIDEAE
PELTANDREAE
Protarum
Alocasia
Steudnera
Colocasia
Remusatia
Gonatanthus
Scaphispatha
Ariopsis
Caladium
Hapaline
Jasarum
Syngonium
Xanthosoma
Chlorospatha
PHYLOGENETIC RELATIONSHIPS WITHIN ARACEAE
69
1-22 Section A Acro 18/7/97 8:02 Page 70
Major Groups
PROTO-ARACEAE
Subfamilies
GYMNOSTACHYDOIDEAE
1 genus
ORONTIOIDEAE
3 genera
POTHOIDEAE
4 genera
MONSTEROIDEAE
12 genera
TRUE ARACEAE
Flowers
bisexual
LASIOIDEAE
10 genera
CALLOIDEAE
1 genus
AROIDEAE
74 genera
Flowers
unisexual
Figure 11. Cladogram of the subfamilies of the Araceae, based on a consensus tree (Mayo et al., in prep.), showing the Major
Groups and subfamilies recognised in the classification, and the distribution of floral sexuality amongst these taxa.
There is a question as to precisely where to draw the
boundary of the subfamily. Our cladogram offers two
possibilities which are supported by strong characters.
A subfamily Aroideae which excluded the tribes
Zamioculcadeae and Stylochaetoneae would be defined
by absence of perigone, presence of simple laticifers,
thick stamen connectives and porose anther dehiscence.
By contrast, subfamily Aroideae including these tribes
is defined by unisexual flowers, clear differentiation of
the spathe into a tube and blade, and spadix differentiated into male and female zones. The latter, more
inclusive concept is a better fit with the DNA cladogram
of French et al. (1995). A further consideration is that
these characters are of more practical use for distinguishing subfamily Aroideae, since unisexuality and
gross morphology of the inflorescence is a much more
obvious combination of features than absence of a
perigone, presence of laticifers or small floral characters.
This is therefore the concept we have opted for.
Despite our strong advocacy of this taxon, it should
be pointed out that the distribution of certain characters on the cladogram, especially inaperturate pollen,
is unsatisfactory. Inaperturate pollen arises between
tribe Spathiphylleae and the other monsteroid clade
low down on the stem of the cladogram, requiring the
70
THE GENERA OF ARACEAE
re-evolution of monosulcate pollen from inaperturate
in subfamily Lasioideae. This seems highly implausible.
A much more likely arrangement would have inaperturate pollen evolving between Stylochaeton and tribe
Spathicarpeae, in association with loss of perigone.
Inaperturate pollen in tribe Spathiphylleae and
Anadendrum would then be homoplasic. A further
point here is that V. Tarasevich (pers. comm.) has suggested on the basis of TEM studies that Spathiphyllum
pollen is in fact multi-aperturate.
The internal topology of our subfamily Aroideae
concept remains largely unresolved above the tribal
level and this is a problem to which future phylogenetic
studies should devoted. We have, for convenience,
recognized an informal paraphyletic “Perigoniate
Aroideae” and a monophyletic “Aperigoniate Aroideae”,
the latter supported by strong characters as noted earlier. Our analysis has thus not made very much further
progress in clarifying the relationships of the tribes of
the Englerian subfamilies Aroideae, Philodendroideae
and Colocasioideae.
Under the influence of the molecular studies of
French et al. (1995), we have adopted Grayum’s
(1984,1990) device of grouping certain tribes into informal Alliances (see chapter 23). The Dieffenbachia
1-22 Section A Acro 18/7/97 8:02 Page 71
Alliance is taken directly from their results. Our analysis never associated tribes Spathicarpeae and
Dieffenbachieae, but we think this is a very interesting
possibility and the molecular results give strong support to this clade. Recognition of the Philodendron
Alliance reflects the fact that both morphological and
molecular analyses gave a similar result. The
Schismatoglottis Alliance is a strong clade in the molecular analysis and although not present in our analysis
with Tofieldia as outgroup, it was commonly found in
analyses with other outgroups.
The Caladium Alliance is a novel group which
emerged strongly in the molecular analysis of French
et al. (1995). In our morphological analysis tribe
Zomicarpeae was problematic, failing to emerge as a
monophyletic group and on the whole being associated with the clade including tribe Areae. The results
of French and colleagues reconcile the known presence of anastomosing laticifers in tribe Zomicarpeae
with their occurrence in tribe Caladieae, the neotropical distribution of both tribes and the possibly
intermediate status of Scaphispatha between them. On
this basis we have adopted their result for our classification. One of the consequences of this is that the old
Englerian subfamily Colocasioideae is no longer recognized in the classification, despite the fact that it
emerges consistently in our morphological analysis.
This clade is associated in our analysis with the tribes
Peltandreae and Ariopsideae and this larger clade
(Peltandreae–Chlorospatha in Figure 10) is defined by
the following synapomorphies:– short distinct leaf basal
ribs, presence of a sympodial leaf submarginal vein,
thickened stamen connectives, connate stamens, presence of staminodes in the female spadix zone, and
base chromosome number of x=14.
The other tribes are not arranged into Alliances and
their sequence reflects only a generalized affinity as we
prefer to remain non-committal. In our analysis a consistent group is formed by Arisarum, Ambrosina and
Pistia. With Tofieldia as outgroup, tribe Arophyteae
also associated consistently with these three genera,
although with other outgroups it emerged in a different position. French et al. (1995) found a somewhat
similar result, except that tribe Pistieae grouped with
the tribes Areae and Colocasieae. We have followed
their results in keeping Pistieae separate.
Clearly there are many possibilities for alternative
topologies within subfamily Aroideae. The tribes of
subfamily Aroideae are likely to remain, more-or-less
as circumscribed here, as reliable taxonomic units,
but it may be expected that in the future they will
undergo much rearrangement. The cost of our
approach is measured in redundancy in the classification since there are still many monotypic tribes. A
desirable future objective would be to find partners
for these solitary genera since in our opinion a classification is more useful if it emphasizes sister group
relationships rather than degree of anagenesis.
Monotypic tribes are a way of roughly indicating that
a genus has no obvious sister group relationships.
These should therefore be priority targets for improving the classification in the future.
PHYLOGENETIC RELATIONSHIPS WITHIN ARACEAE
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22 P R E V I O U S C L A S S I F I C AT I O N S
C
Excellent surveys have been published by Nicolson
(1960a, 1983,1984a, 1988b) and Croat (1992c). We have
discussed only those systems which have, in our opinion, exercised most influence on the progress of
araceous systematics.
Schott, the founding father of the systematics of
Araceae, published his first classification in the
Meletemata botanica (Schott 1832). He grouped 35
genera into the Araceae and placed Gymnostachys and
Acorus in a separate family “Ordo Acoroideae”. Within
his Araceae he divided the genera with unisexual, naked
(i.e. perigone absent) flowers into subfamily (“Subordo”)
Androgynanthae, and those with bisexual, perigoniate
flowers into subfamily Hermaphroditanthae. The order
of genera progressed essentially from those which,
according to our modern paradigm, had the most
derived inflorescence and floral types, to those with the
least, beginning with Cryptocoryne and Ambrosina and
ending with Symplocarpus and Orontium.
Although twenty eight years elapsed before Schott
(1860) published his final classification in the
Prodromus systematis Aroidearum, now greatly
expanded to include 107 genera, the fundamentals of
his classification remained the same (see Appendix,
Table 10). The “Araceae” have now become the
“Aroideae”, Gymnostachys and Acorus are included as
a subtribe at the end of the system, and the two subfamilies are renamed as rankless taxa, the Diclines,
containing those with unisexual, naked flowers and the
Monoclines, containing those with bisexual, perigoniate
flowers. A notable feature of Schott’s Prodromus treatment is the extremely detailed family description which
shows that Schott was fully aware of the great variety
of vegetative characters of the Araceae, including latex
(“succo decolori l. lacteo”) and, probably, trichosclereids
(“rhaphidibus”). His suprageneric taxa are, nevertheless, based almost entirely on floral characters. Only the
tribes and subtribes are ranked. The higher, unranked
taxa have names which describe their most important
diagnostic character, e.g. “Efilamentatae”: filaments
absent, “Pachyzeugmaticae”: large anther connectives,
“Stenozeugmaticae”: slender anther connectives,
“Orthotropooae”: orthotropous ovules, “Anatropooae”:
anatropous ovules, “Gymnogoneae”: gynoecium naked,
and “Peristatogoneae”: gynoecium with associated staminodes. Schott (1860) used vegetative characters
occasionally in the diagnoses of his tribes and subtribes
and much more extensively in the generic descriptions.
There is no evidence that Schott used evolutionary
principles in his work. His philosophy was clearly that of
classification by “natural affinities”, i.e. grouping together
those taxa which have the largest number of taxonomi-
72
THE GENERA OF ARACEAE
cally important characters in common. For Schott, it may
be supposed that the most significant taxonomic characters were the floral ones he had so painstakingly
elucidated and magnificently illustrated in the Genera
Aroidearum (Schott 1858), where the plates presented
each genus as an analysis of its floral structure.
Engler, however, considered Schott’s classification to be artificial because it was based primarily on
floral characters. His new approach was strongly
influenced by the earlier morphological and anatomical studies of Irmisch (1858, 1874) and Tieghem
(1867, 1872) and by his own original research on the
anatomy and shoot organization of the family (Engler
1877, 1878). In his first complete system Engler
(1876b) presented the first classification based on
phylogenetic principles (see Appendix, Table 11).
The order of the genera was reversed so that those
with the least derived flowers and inflorescences
came first and those with the most derived came last.
Ambrosina and Cryptocoryne, for example, were now
placed almost at the end of the system. He recognized 10 subfamilies, one of which was the
Lemnoideae, corresponding to the modern
Lemnaceae. Subfamily Pothoideae was the group
which represented the most primitive forms, i.e.
those with the most obvious connections to other
monocot families through the joint possession of
such common characters as 3-merous, perigoniate,
bisexual flowers. The subfamilies were defined by a
combination of vegetative and floral characters, with
a strong emphasis on the presence or absence of
laticifers and trichosclereids, life form, shoot organization, leaf venation and phyllotaxis. His subfamily
classification embodied the idea of the evolution of
unisexual-flowered genera from bisexual-flowered
ones in several independent phylogenetic lines, or
clades as we would say today.
Engler’s attitude to Schott’s system and the phylogenetic method he applied to his own classification of
the Araceae are summarized explicitly in his 1876
paper, which includes detailed dendrograms showing
presumed phylogenetic relationships (orig.
“Verwandtschaft”) between suprageneric taxa. The
introductory paragraph is worth quoting in full (freely
translated from German) for the light it sheds on
Engler’s thinking:–
“Natural system of the Araceae.
In the following overview of the Araceae, which
is systematic rather than analytical, the [suprageneric]
groups and genera are arranged so as to convey an
idea of the gradual reduction in floral parts [which is
seen in the family]. This system makes it possible to
1-22 Section A Acro 18/7/97 8:02 Page 73
perceive with particular clarity that reduction in the
floral parts must have occurred in various [suprageneric] groups and thus that Schott’s classification, in
which the primary subgroups are based on the floral
structure, is unnatural. My system of the Araceae
would have been quite different had I been aiming to
provide an aid to identification for botanists less familiar with the family. My intention is otherwise: to make
as clear as possible all the phylogenetic relationships
[orig. “verwandtschaftlichen Beziehungen”] existing
between the individual [suprageneric] groups. The
number of suprageneric groups is consequently larger
than might at first sight seem necessary. The Araceae
is a poorly represented family in herbaria. Our knowledge of its forms continues to be incomplete, as is
shown by the almost annual discovery of new genera,
and it may be expected that some of the suprageneric
groups comprising only a few genera will later be
enriched by the inclusion of one or several [new]
ones. All [literature] citations are here omitted since
these will be found in my monographic systematic
treatment of the Araceae [he must have been referring
to his forthcoming monograph in de Candolle’s
Monographiae Phanerogamarum – see Engler 1879]
and are here of little interest. In those cases where the
origin of one genus from another is [considered]
highly probable the names are arranged one above
the other. Where only a common origin [for the genera] is assumed, their names are placed side-by-side.
Generic names in parentheses refer to taxa considered
as genera by Schott but which most probably should
be considered only as subgenera.”
This earliest classification represents the most creative phase of Engler’s Araceae work. It was produced
during the period when he was most competely
immersed in his studies of the family and was not yet
burdened by the immensely ambitious projects of his
later career. The dendrograms, published again in de
Candolle’s Monographiae Phanerogamarum (Engler
1879), were by far the most detailed cladistic statement that he ever published. Later on, following the
discovery and description of many new genera and
innumerable new species, he modified his system
somewhat (Engler 1887-1889, 1920b), in particular by
the exclusion of Lemnaceae, but the essential structure continued unaltered.
In his final classification, Engler (1920b) reduced
the number of subfamilies to eight (see Appendix,
Table 12). These are based on a rather broad range
of taxonomic characters but for the most part are not
very sharply defined. As Engler had made clear from
the outset, they were concepts intended to convey
phylogenetic meaning rather than ease the path of
identification. In a rough and ready manner subsequent specialists of the family learned to recognize
subfamily Pothoideae by their complete lack of laticifers, subfamily Monster oideae by their
trichosclereids and mostly aperigoniate bisexual flowers, subfamily Calloideae by their temperate Northern
hemisphere distribution and preference for swampy
habitats, subfamily Lasioideae by their frequent possession of deeply sagittate or dracontioid leaves,
subfamily Philodendroideae by their unisexual flowers and parallel-pinnate leaf venation, subfamily
Colocasioideae by their unisexual flowers, anastomosing laticifers and special type of leaf venation
(“colocasioid”; see glossary), and subfamily Aroideae
by their unisexual flowers, mostly geophytic habit
and frequent possession of a smooth terminal spadix
appendix. This classification has been the basis for
most subsequent taxonomic work on the family and
it is only in recent years that it has undergone substantial alteration.
To begin with, only minor modifications were
made. Bogner (1979a) published a synopsis in which
new genera were inserted into Engler’s framework and
new generic synonymy accounted for. Shortly afterwards, however, French and French & Tomlinson
began to publish a series of anatomical studies which
suggested that some parts of Engler’s classification
were unnatural, particularly his subfamilies Pothoideae
and Lasioideae. Engler’s concept of araceous phylogeny allowed for the evolution of unisexual-flowered
genera from bisexual-flowered ones within these two
subfamilies and thus he saw no difficulty in including
unisexual-flowered genera such as Culcasia and tribe
Zamioculcadeae within subfamily Pothoideae, and
likewise Amorphophallus, Anchomanes and others
within subfamily Lasioideae. The new anatomical evidence, however, began to reveal that such placements
did not reflect real relationships.
Two earlier classifications should be mentioned
which essentially followed the principles of Schott’s
system, those of Hooker (1883) and Hutchinson (1934,
1959, 1973). Hooker (1883) presented a classification
which was essentially an updated version of Schott’s
(1860) system in the light of Engler’s new studies. Like
Schott’s (1860), the classification starts with the unisexual-flowered genera and ends with the
bisexual-flowered ones. Hooker recognized 11 tribes
but no subfamilies, and placed all the most primitive
genera (Orontium, Lysichiton, Symplocarpus, Lasia,
Podolasia, Urospatha, Anaphyllum, Ophione (=
Dracontium), Cyrtosperma, Spathiphyllum, Anthurium,
Pothos, Pothoidium, Acorus and Gymnostachys) in the
final tribe, Orontieae, divided into seven subtribes. The
98 genera recognized have similar circumscriptions to
those of Schott and Engler.
Hutchinson (1934, 1959, 1973) based his system on
Hooker’s but reversed the order of the genera to reflect
a phylogenetic sequence, starting with the bisexualflowered genera and ending with the unisexual-flowered
ones. The first tribes are Acoreae, Orontieae and
Spathiphylleae and the last is Areae. He recognized 18
tribes and 126 genera but no subfamilies. The major
contribution of his classification was the publication of
a key to all the genera in English. Hutchinson’s system
was used, notably, by Thanikaimoni (1969) and
PREVIOUS CLASSIFICATIONS
73
1-22 Section A Acro 18/7/97 8:02 Page 74
Marchant (1970, 1971a, b, 1972, 1973), but in general it
made little impact on the prevailing use of the Engler
system. There are a number of unnatural tribal circumscriptions, for example, the separation of Symplocarpus
from Lysichiton and Orontium, of Holochlamys from
Spathiphyllum and of Pycnospatha from Dracontium
and related genera. The treatments of Hooker and
Hutchinson were parts of general classifications of the
Flowering Plants rather than specialist studies as in the
case of most other systems mentioned here.
Hotta (1970) published a classification of Araceae
of east Asia and the Malaysian region which was based
on Engler’s system. Among other original ideas, it is
notable for the recognition of the subfamily Acoroideae
(Acorus and Gymnostachys) and the sinking of subfamily Monsteroideae into subfamily Pothoideae. He
transferred Lysichiton and Symplocarpus (as tribe
Symplocarpeae) to subfamily Lasioideae and Calla to
subfamily Philodendroideae. All these concepts were
adopted, at least in part, by later authors, such as
Grayum (1984, 1990) and Bogner & Nicolson (1991).
Grayum (1984,1990) published a comprehensive
survey of aroid taxonomic characters, an original comparative survey of pollen morphology and a cladistic
analysis of the entire family. He presented a very different-looking picture of the family’s taxonomy to that
of Engler (see Appendix, Table 13). In the first place
he argued forcefully for the exclusion of Acorus from
the family altogether, which strengthened considerably the homogeneity of the Araceae as a result. Major
alterations of all the subfamilies were proposed,
including those suggested by Hotta (1970). Engler’s
subfamily Pothoideae and subfamily Monsteroideae
were merged. Subfamily Calloideae was split, with
Calla going to join the genera of the old subfamily
Philodendroideae and the three genera of Engler’s
tribe Symplocarpeae being transferred to the subfamily Lasioideae. Engler’s tribe Amorphophalleae (= tribe
Thomsonieae) was shifted to subfamily Aroideae, and
his tribes Nephthytideae and Montrichardieae were
moved to the subfamily Philodendroideae (= subfamily Calloideae). The Lasioideae also acquired
Stylochaeton from tribe Aroideae. Subfamily
Philodendroideae was renamed Calloideae, because of
the inclusion of Calla, and enlarged yet further with
the inclusion of tribes Spathicarpeae (Engler’s
Asterostigmateae), Callopsideae, Arophyteae and
Culcasieae. Subfamily Colocasioideae changed only
slightly with the addition of Zomicarpa. Subfamily
Aroideae was modified by the inclusion of Pistia as a
tribe, tribe Thomsonieae and Ariopsis.
These changes eliminated certain characters which
had helped to preserve the integrity of Engler’s subfamilies. In particular, parallel-pinnate leaf venation
ceased to be a useful character for defining subfamily
Philodendroideae (= Grayum’s subfamily Calloideae).
However, Grayum preserved the essentially Englerian
concept of independent evolution of unisexual-flowered groups from bisexual-flowered ancestors in various
74
THE GENERA OF ARACEAE
different clades. His subfamilies Pothoideae and
Lasioideae both include unisexual-flowered genera
(tribe Zamioculcadeae and Stylochaeton respectively).
His subfamilies Calloideae (Philodendroideae),
Colocasioideae and Aroideae consist almost entirely of
unisexual-flowered genera as in Engler’s system.
Grayum’s work has been crucial to the re-evaluation
of the family classification. Not only was it based on a
thorough review of the available taxonomic data from
many character fields, both old and new, but he
employed modern analysis to produce his classification
and was bold in proposing major changes backed up
by cogent arguments. Grayum presented extensive discussion and a masterful revision of the literature but did
not summarize his conclusions in the form of a detailed
taxonomic presentation with diagnoses and keys to
his generic and suprageneric taxa.
Bogner & Nicolson (1991) presented a classification
which adhered more closely to Engler’s subfamily concepts but which likewise took account of new data,
especially that of French (see Appendix, Table 14).
Their primary aim was to provide a detailed synoptical key to the genera, in which the diagnostic
characters were clearly presented. The mass of new
data on which their changes were based was not
detailed in the form of literature citations. They followed Grayum in eliminating Acorus, but in addition
they elevated Gymnostachys to subfamilial rank.
Subfamily Pothoideae was greatly altered. All unisexual-flowered genera were ejected to other subfamilies
and Anadendrum and Heteropsis were transferred to
subfamily Monsteroideae, leaving only three closely
related genera (Pothos, Pedicellarum and Pothoidium).
Subfamily Monsteroideae acquired the circumscription accepted in our treatment by the addition of
Anadendrum and Heteropsis. Subfamily Calloideae
was reduced to include only Calla, while subfamily
Lasioideae now included tribes Orontieae (= Engler’s
tribe Symplocarpeae), Anthurium, Zamioculcadeae,
Callopsideae, Nephthytideae, Culcasieae and
Montrichardieae, as well as the “core” tribe Lasieae.
Subfamilies Philodendroideae, Colocasioideae and
Aroideae, however, remained very much as Engler had
left them, apart from the inclusion of more recently
described genera and the transfer of Protarum to subfamily Colocasioideae, and tribe Thomsonieae to
subfamily Aroideae. Pistia remained in its own subfamily as proposed by Engler.
Bogner & Nicolson’s paper was the first detailed
taxonomic synopsis down to the level of genera published by specialists of the family since Engler’s time.
It was the result of many years of study and a profound
and first-hand knowledge of the taxonomic characters
of the genera. Although these authors proposed no
explicit phylogenetic scheme, their simplification of
subfamilies Pothoideae and Calloideae reduced the
number of subfamilies which included both unisexual-flowered and bisexual-flowered genera to one,
their much-expanded subfamily Lasioideae.
1-22 Section A Acro 18/7/97 8:02 Page 75
Hay & Mabberley (1991) took a completely different approach to the question of araceous phylogeny,
starting out from the precepts of the durian theory of
Corner (1949, 1952, 1953, 1954a, 1954b). In a long
paper bursting with fascinating if unorthodox ideas,
they drew a picture of an ancestral araceous type and
recognized many features of the Lasieae (our
Lasioideae) as primitive, partly through their correspondence with Corner’s hypotheses of primitive
angiosperm characters. One point they bring out is
that an argument for adaptation in a particular character state does not necessarily support a hypothesis
that it is derived in the taxon under consideration.
Thus, there is no reason in principle why the ancestral aroid should not have had a tuberous stem and
unilocular ovaries with a single basally inserted
ovule. They proposed that the araceous inflorescence
may have been the result of homoeotic saltation from
Nymphaealean ancestral forms and therefore that the
typically monocotyledonous features observed in some
genera (i.e. those that we consider plesiomorphic
in Araceae) are really derived convergences. They
presented a classification based largely on Grayum
(1990) but differing in a number of significant
respects. The Lasioideae are placed first, and the
Pothoideae and Monsteroideae are recognized as separate subfamilies, the former including Anthurium,
Anadendrum, Heteropsis and the Zamioculcadeae and
the latter with only the Monstereae and the
Spathiphylleae. The Aroideae retains the Spathicarpeae,
as in Engler’s system, but also includes Ariopsis,
Thomsonieae and Pistia.
The classification presented here (chapter 23),
together with the results of the molecular studies of
French et al. (1995), differs from other modern systems
and that of Engler in grouping all unisexual-flowered
genera together, as Schott did. Unlike Schott, however,
our proposal is explicitly phylogenetic. In essence, it
appears that the configuration of the available taxonomic data favours a simpler hypothesis than Engler
proposed, and indeed modern results flatly contradict
Engler’s view of araceous phylogeny. It is not necessary
to hypothesize the multiple evolution of unisexual flowers to arrive at a natural classification of Araceae.
PREVIOUS CLASSIFICATIONS
C
75
23-25 Section B Acro 17/7/97 16:35 Page 77
B
TAXONOMY
23-25 Section B Acro 17/7/97 16:35 Page 78
23 S Y N O P S I S O F T H E C L A S S I F I C AT I O N O F A R A C E A E
C
Family Araceae Jussieu
MAJOR GROUP PROTO-ARACEAE
a. Flowers bisexual
I. Subfamily Gymnostachydoideae Bogner &
Nicolson
1. Gymnostachys R. Brown
II. Subfamily Orontioideae Mayo, Bogner
& P.C. Boyce
2. Orontium L.
3. Lysichiton Schott
4. Symplocarpus Nuttall
V. Subfamily Lasioideae Engler
21. Dracontium L.
22. Dracontioides Engler
23. Anaphyllopsis A. Hay
24. Pycnospatha Gagnepain
25. Anaphyllum Schott
26. Cyrtosperma Griffith
27. Lasimorpha Schott
28. Podolasia N.E. Brown
29. Lasia Loureiro
30. Urospatha Schott
VI. Subfamily Calloideae Endlicher
31. Calla L.
MAJOR GROUP TRUE ARACEAE
a. Flowers bisexual
b. Flowers unisexual
III. Subfamily Pothoideae Engler
VII. Subfamily Aroideae
Tribe
5.
6.
7.
PARAPHYLETIC GROUP: PERIGONIATE
AROIDEAE (perigone present)
Potheae Engler
Pothos L.
Pedicellarum M. Hotta
Pothoidium Schott
Tribe Anthurieae Engler
8. Anthurium Schott
IV. Subfamily Monsteroideae Engler
Tribe Spathiphylleae Engler
9. Spathiphyllum Schott
10. Holochlamys Engler
78
Tribe Zamioculcadeae Engler
32. Zamioculcas Schott
33. Gonatopus Engler
Tribe Stylochaetoneae Schott
34. Stylochaeton Leprieur
MONOPHYLETIC GROUP: APERIGONIATE
AROIDEAE (perigone absent)
Tribe Anadendreae Bogner & French
11. Anadendrum Schott
Dieffenbachia Alliance
Tribe Heteropsideae Engler
12. Heteropsis Kunth
Tribe Dieffenbachieae Engler
35. Dieffenbachia Schott
36. Bognera Mayo & Nicolson
Tribe Monstereae Engler
13. Amydrium Schott
14. Rhaphidophora Hasskarl
15. Epipremnum Schott
16. Scindapsus Schott
17. Monstera Adanson
18. Alloschemone Schott
19. Rhodospatha Poeppig
20. Stenospermation Schott
Tribe Spathicarpeae Schott
37. Mangonia Schott
38. Taccarum Schott
39. Asterostigma F.E.L. Fischer & C.A. Meyer
40. Gorgonidium Schott
41. Synandrospadix Engler
42. Gearum N.E. Brown
43. Spathantheum Schott
44. Spathicarpa W.J. Hooker
THE GENERA OF ARACEAE
23-25 Section B Acro 17/7/97 16:35 Page 79
Philodendron Alliance
Tribe Philodendreae Schott
45. Philodendron Schott
Tribe Homalomeneae M. Hotta
46. Furtadoa M. Hotta
47. Homalomena Schott
Tribe Anubiadeae Engler
48. Anubias Schott
Schismatoglottis Alliance
Tribe Schismatoglottideae Nakai
49. Schismatoglottis Zollinger & Moritzi
50. Piptospatha N.E. Brown
51. Hottarum Bogner & Nicolson
52. Bucephalandra Schott
53. Phymatarum M. Hotta
54. Aridarum Ridley
55. Heteroaridarum M. Hotta
Tribe Cryptocoryneae Blume
56. Lagenandra Dalzell
57. Cryptocoryne Wydler
Caladium Alliance
Tribe Zomicarpeae Schott
58. Zomicarpa Schott
59. Zomicarpella N.E. Brown
60. Ulearum Engler
61. Filarum Nicolson
Tribe Caladieae Schott
62. Scaphispatha Schott
63. Caladium Ventenat
64. Jasarum Bunting
65. Xanthosoma Schott
66. Chlorospatha Engler
67. Syngonium Schott
68. Hapaline Schott
No Alliance
Tribe Nephthytideae Engler
69. Nephthytis Schott
70. Anchomanes Schott
71. Pseudohydrosme Engler
Tribe Aglaonemateae Engler
72. Aglaonema Schott
73. Aglaodorum Schott
Tribe Culcasieae Engler
74. Culcasia Palisot de Beauvois
75. Cercestis Schott
Tribe Montrichardieae Engler
76. Montrichardia H. Crüger
Tribe Zantedeschieae Engler
77. Zantedeschia K. Sprengel
Tribe Callopsideae Engler
78. Callopsis Engler
Tribe Thomsonieae Blume
79. Amorphophallus Decaisne
80. Pseudodracontium N.E. Brown
Tribe Arophyteae Bogner
81. Arophyton Jumelle
82. Carlephyton Jumelle
83. Colletogyne Buchet
Tribe Peltandreae Engler
84. Peltandra Rafinesque
85. Typhonodorum Schott
Tribe Arisareae Dumortier
86. Arisarum P. Miller
Tribe Ambrosineae Schott
87. Ambrosina Bassi
Tribe Areae
88. Arum L.
89. Eminium (Blume) Schott
90. Dracunculus P. Miller
91. Helicodiceros K. Koch
92. Theriophonum Blume
93. Typhonium Schott
94. Sauromatum Schott
95. Lazarum A. Hay
96. Biarum Schott
Tribe Arisaemateae Nakai
97. Pinellia Tenore
98. Arisaema Martius
Tribe Colocasieae Engler
99. Ariopsis Nimmo
100. Protarum Engler
101. Steudnera K. Koch
102. Remusatia Schott
103. Colocasia Schott
104. Alocasia G. Don
Tribe Pistieae Blume
105. Pistia L.
C
SYNOPSIS OF THE CLASSIFICATION
79
23-25 Section B Acro 17/7/97 16:35 Page 80
24 FA M I L Y D E S C R I P T I O N O F A R A C E A E
C
Family Araceae
Araceae Juss., Gen. Pl. 23 (1789, “Aroideae”), nom.
cons.
ANATOMY: Calcium oxalate raphides and druses abundant, raphides always present, laticifers commonly
present, either simple and articulated or more rarely
anastomosing, trichosclereids present (Monstereae,
Spathiphylleae, rarely in Potheae), tannin cells common, resin canals sometimes present (Culcasieae,
Homalomeneae, Philodendreae). HABIT: evergreen to
seasonally dormant herbs, perennial, sometimes gigantic, climbing or subshrubby hemiepiphytes, epiphytes,
lithophytes, terrestrial, geophytes, helophytes, sometimes rheophytes, true aquatics, rarely free-floating
(Pistia). STEM: aerial and erect to climbing or creeping
with very short (plant rosulate) to very long (plant
scandent) internodes, or subterranean and consisting of
a subglobose to depressed-globose tuber (sometimes
turnip- or carrot-like or irregular in shape) or horizontal to erect rhizome; terrestrial plants and helophytes
sometimes arborescent with massive stem and terminal
rosette of leaves (Xanthosoma, Alocasia, Montrichardia, Philodendron) or arborescent with a pseudostem
of petiole sheaths (large in Typhonodorum, small in
many Arisaema); geophytes often with solitary leaf.
SHOOT ORGANIZATION: the mature, flowering stem is
almost always a sympodium composed of a series of
articles, rarely the stem is monopodial (Potheae,
Heteropsideae); each article begins with a 2-keeled
(except Orontioideae) prophyll followed by a series of
leaves and terminates with an inflorescence; leaf number per article may be determinate or indeterminate,
and from one or very few to very many; the leaves of
each article normally consist of a mixture of foliage
leaves with partially to fully developed blades and cataphylls; the sympodial leaf is that subtending the
inflorescence and may be a foliage leaf or a cataphyll;
the prophyll is almost always a cataphyll (except
Orontioideae); subsequent articles (continuation
shoots) normally arise at the second node below the
spathe node (except Orontioideae); juvenile shoots
and flagelliform branches are usually monopodial; terminal inflorescences may be solitary or may form a
floral sympodium of several inflorescences; the articles of floral sympodia normally consist of a single
2-keeled prophyll and an inflorescence; the subsequent article of a floral sympodium normally arises in
the axil of the preceding prophyll, i.e. at the first node
below the spathe node. VEGETATIVE PROPAGATION:
climbing hemiepiphytes frequently form flagelliform
80
THE GENERA OF ARACEAE
shoots, which are stolon-like branches with leaves
reduced to small cataphylls and very elongated internodes, adapted to seek out new host trees; other
adaptative forms are subterranean stolons (e.g.
Spathiphyllum, Lasimorpha) and tubercules (e.g.
Dracontium), bulbils with recurved scales borne on
specialized shoots (Remusatia), bulbils on petioles
(Pinellia ternata) or leaf blade (Amorphophallus bulbifer), or formation of new plants from abscissed leaflets
(Zamioculcadeae). ROOTS: always adventitious, primary root withering soon after germination, sometimes
dimorphic (climbing hemiepiphytes) with anchor roots
and larger feeder roots, sometime contractile roots present (geophytes), rarely roots very fleshy, water-storing
(Stylochaeton). LEAVES: usually spirally arranged,
sometimes distichous; normally differentiated into petiole and expanded blade (except e.g. Gymnostachys,
some Biarum spp.), usually glabrous, rarely pubescent, tomentose, villous or with small to large and
complex trichomes or papillae (e.g. Philodendron
squamiferum) on the petiole; ptyxis usually convolute, rarely involute (e.g. Anthurium sect.
Pachyneurium, Lagenandra); blade and petiole often
variegated or mottled with spots, bands, blotches or
irregularly shaped patches and zones of various
colours, usually shades and mixtures of green, yellow
and silver. CATAPHYLLS: caducous, marcescent, deciduous or persistent, sometimes beautifully mottled and
patterned (e.g. Arisaema, Asterostigma), when persistent sometimes a conspicuous feature of plant and
either membranous or forming fibrous mass (e.g. many
spp. of Anthurium, Philodendron). PETIOLE: often as
long as or longer than blade, usually smooth, sometimes hairy, papillose, warty, prickly or aculeate (e.g.
Lasioideae), occasionally covered with large multicellular processes (e.g. Philodendron squamiferum),
rarely massively succulent and water-storing (e.g.
Zamioculcas, Philodendron martianum), often geniculate (pulvinate) apically (e.g. Anthurium), basally or
rarely centrally (e.g. Gonatopus boivinii); sheath normally well-developed, often at least half as long as
entire petiole, sometimes ligulate apically, often very
reduced in sympodial leaves (especially in Anthurium,
most Philodendron spp.). LEAF BLADE: simple to compound, extremely variable in shape – rarely filiform
(e.g. Cryptocoryne consobrina), linear (Jasarum), most
commonly elliptic, ovate, oblong, sagittate, hastate,
less commonly trifid to trisect, pedatifid to pedatisect,
radiatisect, dracontioid (i.e. trisect with each primary
division further much divided), pinnatifid to pinnatisect
(Zamioculcas), bipinnatifid, tripinnatifid to quadripinnatifid (Gonatopus), fenestrate (Monstera) or laciniate
23-25 Section B Acro 17/7/97 16:35 Page 81
(i.e. fenestrate with slit-like holes, Cercestis mirabilis);
heteroblasty frequent, especially in climbing hemiepiphytes, “shingle leaves” sometimes formed (e.g. some
Potheae, some Monstereae); seedling leaves usually
entire when epigeal, rarely first foliage leaf compound
(Gonatopus, Amorphophallus). LEAF VENATION:
midrib almost always differentiated, sometimes massive
and succulent (e.g. Philodendron crassinervium); primary veins usually arising pinnately from midrib (and
then called primary lateral veins), either running into
marginal vein (e.g. Philodendron, Dieffenbachia) or
joining distally to form a submarginal collective vein on
each side (e.g. Caladium, many Anthurium spp.),
sometimes primary veins all arising from petiole insertion and running arcuately into leaf apex (e.g.
Orontium, Anthurium sect. Digitinervium), rarely
strictly parallel (Gymnostachys) or subparallel (Pistia),
sometimes not differentiated at all (e.g. Philodendron
crassinervium); secondary and tertiary veins either
reticulate (e.g. Areae), or parallel-pinnate, i.e. running
parallel to primaries (e.g. Philodendron), or arising
from primaries at a wide angle and then arching
strongly towards leaf margin (e.g. Colocasia), sometimes forming sinuous or zig-zag interprimary veins
(e.g. Caladieae); higher order venation reticulated or
forming cross connections between lower order veins.
INFLORESCENCE: terminal, solitary, or 2 to many in a
synflorescence, usually appearing to be axillary to sympodial leaf, consisting of a spadix (spike) of small
flowers and subtended by a spathe (bract), usually
erect, sometimes pendent (e.g. Anthurium wendlingeri, Stenospermation, Piptospatha), sometimes
becoming pendent after anthesis (e.g. Typhonodorum).
PEDUNCLE: very short to very long, usually similar to
petiole in appearance, coloration, pubescence or armature, normally longer than spadix stipe, sometimes ±
suppressed and spadix stipe elongated (Orontium,
Lysichiton). SPATHE: nearly always conspicuous
(except Gymnostachys, Orontium), very variable in
shape and colour, simpler forms (e.g. many Anthurium
spp.) often green, reflexed or spreading, more complex
forms often showy and highly coloured, erect, usually
either boat-shaped or constricted centrally to form a
basal tube and an apical blade; tube may enclose the
female zone of the spadix or both fertile zones or
rarely the entire spadix (e.g. Cryptocoryneae), very
occasionally much longer than blade (e.g. many
Cryptocoryne spp.), tube margins usually convolute,
sometimes connate (e.g. Sauromatum, Stylochaeton,
Arisarum); blade usually erect and gaping, sometimes
widely spreading, twisted, reflexed or rarely margins ±
closed forming slit-like opening (e.g. most Lagenandra
spp.); spathe constriction may lie between or above
male and female zones or occur in two places (e.g.
some Remusatia spp.); spathe entirely deciduous soon
after anthesis (e.g. most Monstereae), or tube persistent
to fruiting and blade marcescent to deciduous after
anthesis (Caladieae, Colocasieae, Schismatoglottideae),
or spathe entirely persistent until fruiting (e.g.
Philodendron, Homalomena) or whole spathe gradually withering and rotting (most Areae). SPADIX:
usually erect, often fleshy and relatively thick, sessile
or shortly stipitate, rarely very long-stipitate (e.g.
Lysichiton, Orontium, some Anthurium spp.), usually
free, sometimes adnate basally (e.g. Hapaline,
Dieffenbachia) or entirely (Spathicarpa) to spathe,
either ± uniform in appearance (flowers bisexual or
monoclinous), or divided into distinct floral zones
(flowers unisexual or diclinous), fertile zones contiguous or separated by sterile zones, female (pistillate)
zone always basal and male (staminate) zone either
apical or intermediate in position (except Spathicarpa),
rarely bisexual flowers occur between male and female
zones (e.g. Arophyteae); sterile zones may be basal,
intermediate or apical or any combination of these, apical sterile zone usually known as a terminal appendix;
rarely a single plant produces inflorescences bearing
male flowers only, followed in later years by inflorescences bearing female flowers only, and vice versa
(paradioecy, known only in Arisaema). FLOWERS: 2- to
3-merous (-mery often hard to detect in unisexual flowers), bisexual (monoclinous, hermaphrodite) or
unisexual (diclinous), very small, protogynous, lacking
floral bracts, usually numerous (except e.g. Pistia,
Ambrosina), sessile (except Pedicellarum), usually
densely arranged, sometimes laxly so (e.g. some Pothos
spp., male flowers of Arisarum, female flowers of
Dieffenbachieae); bisexual flowers with or without
(Calloideae, Monstereae) a perigone (perianth), unisexual flowers usually without a perigone (present in
Zamioculcadeae, Stylochaeton) but sometimes including rudimentary organs representing modified sexual
parts of the other sex (e.g. staminodes of female flowers in Dieffenbachia and Spathicarpeae, cup-like
synandrodium in Arophyteae, pistillodes present in
male flowers of e.g. Stylochaeton, Furtadoa, some
Spathicarpeae spp., central stigmatoid body of the
synandrium present in Taccarum and some
Gorgonidium spp.). PERIGONE: composed of free (e.g.
Anthurium) or partially connate (some Pothos spp.)
tepals, or consisting of a single cup-like structure (e.g.
Spathiphyllum cannifolium); when free, tepals 4 to 6
(–8) and imbricate in 2 whorls, membranaceous (e.g.
Anadendrum) or more commonly thickened at least
apically, truncate (Zamioculcadeae) to cucullate
(Lasioideae). STAMENS (bisexual perigoniate, bisexual non-perigoniate, unisexual perigoniate flowers):
usually free (filaments connate in Gonatopus and often
in Lasimorpha), equal in number and opposite to
tepals (when present), rarely more (e.g. some
Dracontium spp.); filaments distinct, often ± oblong
and flattened (e.g. Anthurium), rarely filiform
(Stylochaeton), usually rapidly elongating to push
anthers above perigone or gynoecium at anthesis;
anthers usually terminal, basifixed, extrorse (introrse in
Zamioculcas, latrorse in Pedicellarum), always composed of 2 thecae each with 2 microsporangia;
connective usually slender, inconspicuous, often over-
FA M I L Y D E S C R I P T I O N
81
23-25 Section B Acro 17/7/97 16:35 Page 82
topped by thecae, thecae dehiscing by single longitudinal slit or apical stomial pore, with all intermediate
degrees occurring. MALE FLOWER (unisexual nonperigoniate flowers): 1–8 androus (rarely more, e.g.
Alocasia brisbanensis), floral grouping of stamens
sometimes obvious in mature inflorescence (e.g. many
Philodendron and Homalomena spp.), often obscured
during ontogeny; stamens free or partially to completely connate to form a synandrium. FREE STAMENS
(unisexual non-perigoniate flowers): usually sessile to
subsessile, filament sometimes distinct (e.g.
Schismatoglottis), connective sometimes ± slender (e.g.
Areae) but often strongly thickened, apically broad,
fleshy and probably osmophoric (e.g. Philodendron),
thecae lying opposite or adjacent on one side of stamen, dehiscing by single longitudinal slit or apical
stomial pore, with all intermediate degrees occurring,
rarely both microsporangia dehiscing independently
by separate stomial pores (some Amorphophallus spp.),
rarely theca prolonged apically into a horn dehiscing by
single pore (Cryptocoryneae, some Schismatoglottideae).
SYNANDRIUM (unisexual non-perigoniate flowers):
usually ± sessile, sometimes formed by fusion of filaments only (e.g. Arisaema, Arisarum, Carlephyton sect.
Pseudocolletogyne, Gorgonidium), more commonly
composed of completely connate stamens and then
usually apically truncate and ± prismatic in apical crosssection (e.g. Caladieae), sometimes mushroom-shaped
(Asterostigma) or cylindric (Taccarum), very rarely the
synandria themselves connate (Ariopsis); common connective usually broad, fleshy and probably osmophoric
(e.g. Caladieae, Alocasia); thecae either lateral, apical
or marginal depending on the degree of elongation of
the thecae and the extent to which they are overtopped
by the common connective, dehiscing by single longitudinal slit or apical stomial pore, with all intermediate
degrees occurring. POLLEN: shed in monads, rarely
shed in tetrads (Xanthosoma, Chlorospatha), aperturate
in most bisexual-flowered genera, inaperturate in most
unisexual-flowered genera, exine various (see chapter
10). STERILE ORGANS (pistillodes, staminodes,
synandrodes): often forming zones between fertile
zones, sometimes present below female zone
(Schismatoglottideae), or on base of terminal appendix,
very variable in shape, most often ± truncate and prismatic (e.g. Philodendron), more rarely filiform,
subulate, bristle-like or elongate-clavate (Areae),
spathulate (Bucephalandra), cylindric (Aridarum) or
enlarged and pearl-like (Amorphophallus margaritifer).
TERMINAL APPENDIX: present only in some genera
(e.g. Thomsonieae, Areae), probably always
osmophoric,
partly
or
completely
(e.g.
Pseudodracontium) covered with staminodes, rugose
or corrugated or entirely smooth (e.g. most Areae), intermediate conditions also occur (e.g. Ulearum).
FEMALE FLOWER (unisexual, non-perigoniate flowers): Gynoecium sometimes surrounded by a whorl of
variously shaped staminodes (e.g. Dieffenbachia,
Spathicarpeae), or sometimes ± regularly associated
82
THE GENERA OF ARACEAE
with a single clavate staminode (e.g. Homalomeneae,
Schismatoglottis). GYNOECIUM (bisexual and unisexual flowers): ovary usually 1–3 locular, rarely more
(e.g. Philodendron, most Spathicarpeae), 1-locular
ovaries probably always pseudomonomerous; ovules
1–many per locule, orthotropous, hemiorthotropous,
campylotropous, amphitropous, hemianatropous or
anatropous; placenta 1–several, axile, parietal, apical,
basal, or basal and apical; stylar region (tissue lying
between ovary and stigmatic epidermis) usually welldeveloped, usually at least as broad as ovary,
sometimes attenuate and elongate (e.g. many
Amorphophallus, Arisaema, Biarum spp., Dracontium,
some Spathiphyllum spp.) or massive and truncate
(most Monstereae spp.), rarely dilated and connate
with those of neighbouring gynoecia (Xanthosoma);
stigma hemispheric, capitate, discoid, umbonate,
more-or-less strongly lobed (e.g. some
Amorphophallus, Dieffenbachia spp.), rarely stellately lobed (Asterostigma), sometimes brightly
coloured (e.g. some Alocasia, Amorphophallus spp.),
always wet from copious stigmatic secretion during
female anthesis, sometimes producing conspicuous
nectar droplet (e.g. Anthurium). FRUIT: normally a
juicy berry, rarely mesocarp leathery; berries normally free, rarely connate (Syngonium) or connate
and dehiscent as a syncarp (Cryptocoryne), usually
red, orange or purplish red, sometimes white (e.g.
some Philodendr on, Stenosper mation), yellow
(Typhonodorum), green (Arophyton buchetii,
Lysichiton, Orontium, Peltandra virginica), very rarely
blue (Amorphophallus kerrii, Gymnostachys), or
brownish (Jasarum); infructescence densely packed,
cylindric to globose, exposed by withering, basal
abscission (e.g. Philodendron) or splitting (e.g.
Alocasia, Dieffenbachia) of spathe, rarely berries
dehiscent, either basally (Lagenandra) or apically with
the seeds exposed by ± simultaneous sloughing of
stylar regions of all berries (e.g. Monstereae). SEED:
1–many per berry; testa thick to thin, smooth, roughened, verrucose or striate-costate, papery in seeds
with highly developed embryos (Gonatopus), sometimes decaying at maturity (Orontium), or lacking
altogether (Gymnostachys, Nephthytis), sometimes arillate with a conspicuous strophiole (e.g. most Areae,
Ambrosina), rarely operculate (e.g. Pistia); embryo
usually straight, sometimes curved (e.g. Cyrtosperma,
Epipremnum), usually undifferentiated, rarely with
highly developed plumule (e.g. Cryptocoryne ciliata,
Orontium, Typhonodorum) and then endosperm lacking and outer cell layers of embryo chlorophyllous;
endosperm copious or absent, with all intermediate
states occurring.
105 genera, over 3300 spp.; distribution subcosmopolitan, most abundant and diverse in tropical latitudes.
C
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C
25 K E Y TO T H E G E N E R A O F A R A C E A E A N D A C O R A C E A E
1. Plants free-floating aquatics; leaves rosulate, hairy; flowers unisexual, naked; inflorescence with a single
female flower and a few male flowers · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 105. Pistia
1. Plants terrestrial or helophytes, climbing hemiepiphytes, epiphytes or lithophytes or other, but never floating
2. Leaves not differentiated into petiole and blade, primary venation strictly parallel; inflorescence borne
on a culm-like axis
3. Leaves ensiform, unifacial; spadix solitary, pseudolateral and overtopped by a single, erect, leaf-like
spathe; flowers 3-merous, tepals 6 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Acorus (Acoraceae)
3. Leaves dorsiventrally flattened, bifacial; flowering shoot with long culm-like axis, bearing numerous
spadices distally, these borne in axillary clusters subtended by elongate bracts; flowers 2-merous,
tepals 4 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 1. Gymnostachys
2. Leaves with distinct petiole and expanded blade, primary venation never strictly parallel
4. Flowers with obvious perigone of free or fused tepals (except Pycnospatha which lacks perigone,
but has dracontioid leaf, tuberous stem and boat-shaped, fornicate spathe – see lead 22)
5. Flowers bisexual, spadix uniform in appearance with flowers of only one type
6. Higher order leaf venation parallel-pinnate; tissues with abundant trichosclereids
7. Spathe persistent; tepals free or connate; ovary 2–4-locular; ovules 2–8 per locule, placenta
axile · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 9. Spathiphyllum
7. Spathe deliquescent; tepals connate; ovary 1-locular; ovules several, placenta basal · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 10. Holochlamys
6. Higher order leaf venation clearly reticulated; tissues without trichosclereids or trichosclereids very few
8. Stem aerial, not tuberous or rhizomatous, never aculeate; plant usually a climbing hemiepiphyte or epiphyte, less often lithophyte or terrestrial, only very rarely helophytic (some spp.
of Anthurium)
9. Neotropical plants; seeds with copious endosperm; pollen usually forate, never monosulcate · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 8. Anthurium
9. Palaeotropical plants; seeds without endosperm; pollen monosulcate or inaperturate
10. Stigma transversely oblong; stamens always 4 per flower; pollen inaperturate; perigone
consisting of a single cup-like structure · · · · · · · · · · · · · · · · · · · 11. Anadendrum
10. Stigma hemispheric to discoid; stamens usually 6 per flower; pollen monosulcate;
perigone usually consisting of free tepals or when connate and cup-like the flowers
are borne on short pedicels
11. Ovary 3-locular; locules 1-ovulate; flowering shoot with inflorescences always
axillary
12. Flowers sessile; tepals free, very rarely basally united · · · · · · · · · 5. Pothos
12. Flowers pedicellate; tepals connate · · · · · · · · · · · · · · · · · 6. Pedicellarum
11. Ovary 1-locular; flowering shoots terminating in a branching system of spadices
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 7. Pothoidium
8. Stem typically subterranean, tuberous or rhizomatous, sometimes aerial and creeping or
scrambling but then aculeate; plant frequently a helophyte
13. Plants of temperate regions (N. America, NE. Asia); leaf blade always entire, ovate to
elliptic
14. Ovary 2-locular; ovules 2 per locule, placenta axile · · · · · · · · · · · · · 3. Lysichiton
14. Ovary 1-locular; ovule 1, placenta apical or basal
15. Placenta basal; spathe inconspicuous; spadix cylindric, stipe very long · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 2. Orontium
15. Placenta apical; spathe thick, ventricose, enclosing spadix; spadix subglobose,
stipe short · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 4. Symplocarpus
13. Plants of tropical and subtropical regions; leaf blade sagittate, pinnatifid, pinnatisect or
dracontioid
K E Y TO G E N E R A
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23-25 Section B Acro 17/7/97 16:35 Page 84
16. Leaf deeply sagittate, anterior division not pinnatifid or pinnatisect
17. Ovary many- to 2-ovulate, rarely 1-ovulate; seeds with endosperm
18. Plants without stolons; petiole spines dispersed; stamen filaments free;
tropical Asia to Oceania · · · · · · · · · · · · · · · · · · · · · · · · 26. Cyrtosperma
18. Plants with long stolons; petiole spines in ridges; stamen filaments free or
connate; tropical West Africa · · · · · · · · · · · · · · · · · · · · · 27. Lasimorpha
17. Ovary 1-ovulate, rarely 2-ovulate; seeds without endosperm or rarely with a
little endosperm
19. Petiole aculeate, with obvious spines; Malay Archipelago · · 28. Podolasia
19. Petiole smooth to scabrid-verrucose, never aculeate; tropical America
20. Leaf blade never fenestrate; spathe lanceolate, very long-acuminate and
usually spirally twisted; ovary locules with (1–)2 to several ovules;
neotropics · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 30. Urospatha
20. Leaf blade often perforated with a few perforations of irregular size
between primary lateral veins; spathe fornicate; endemic to Brazil (coastal
Bahia and Espirito Santo) · · · · · · · · · · · · · · · · · · · 22. Dracontioides
16. Leaf blade pinnatifid, pinnatisect, dracontioid or sometimes ± pedatifid; anterior
division always pinnately divided, either pinnatifid, pinnatisect or yet more highly
divided
21. Stem aculeate, aerial and scrambling to prostrate, internodes distinct, green · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 29. Lasia
21. Stem not aculeate, subterranean, internodes very abbreviated, not green
22. Leaf blade dracontioid, anterior division bipinnatifid or yet more highly
divided; stem a depressed-globose tuber; spathe fornicate
23. Tropical America; flowers with perigone of 4–8 free tepals; berries smooth,
red · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 21. Dracontium
23. Tropical southeast Asia; flowers without perigone; berries aculeate, dark
green · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 24. Pycnospatha
22. Leaf blade pinnatifid, pinnatisect, or sometimes ± pedatifid, anterior division
pinnatifid to pinnatisect; stem a vertical or horizontal rhizome; spathe erect,
not fornicate, blade often spirally twisted apically
24. Tropical America; testa thick, verrucose; embryo curved · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 23. Anaphyllopsis
24. Southern India; testa membranous, smooth; embryo straight · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 25. Anaphyllum
5. Flowers unisexual, spadix clearly divided into basal female zone and apical male zone; tropical
Africa
25. Leaf pinnatisect to tri- or quadripinnatifid; tepals free; spathe margins free
26. Leaf blade pinnatisect; stamens free · · · · · · · · · · · · · · · · · · · · · · · · · 32. Zamioculcas
26. Leaf blade bipinnatifid to quadripinnatifid, at least in lowest pinnae; stamen filaments
connate · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 33. Gonatopus
25. Leaf entire, linear to cordate, sagittate or hastate; tepals connate into cup; spathe margins
connate basally · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 34. Stylochaeton
4. Flowers without perigon of free or fused tepals
27. Flowers bisexual; spadix uniform in appearance with flowers of only one type (sometimes with
sterile flowers at spadix base)
28. Helophytes from temperate regions of northern hemisphere; petiole sheath with long apical
ligule · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 31. Calla
28. Climbing hemiepiphytes or sometimes epiphytes or very rarely rheophytes (few
Rhaphidophora) from tropical regions; petiole sheath non-ligulate or ligule only short
29. Petiole usually very short with non-annular insertion; trichosclereids not present in tissues,
leaf never perforated or lobed; primary lateral veins forming distinct submarginal vein ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 8. Heteropsis
29. Petiole well-developed with annular insertion and usually conspicuous sheath; trichosclereids present in tissues, or if absent (or nearly so) then leaf with conspicuously
reticulate higher order venation and often perforated or lobed (Amydrium); primary lateral veins usually not forming distinct submarginal vein
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THE GENERA OF ARACEAE
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30. Trichosclereids rare or nearly absent; higher order leaf venation completely reticulate;
ovary 1-locular, placenta 1, intrusive-parietal, ovules 2 · · · · · · · · · 13. Amydrium
30. Trichosclereids abundant; higher order leaf venation parallel to primary lateral veins,
or only finest venation reticulate
31. Ovary 1-locular or incompletely 2-locular
32. Ovules anatropous, more than one
33. Ovules numerous, superposed on 2 (rarely 3) parietal placentas; seeds
fusiform, straight, 1.3–3.2 mm long, 0.6–1.0 mm wide · · · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 14. Rhaphidophora
33. Ovules 2–4 (–6) at base of a single intrusive placenta; seeds curved, 3–7
mm long, 1.5–4.0 mm wide · · · · · · · · · · · · · · · · · · 15. Epipremnum
32. Ovules amphitropous to anatropous, solitary, basal
34. Adult leaf blade entire; palaeotropics · · · · · · · · · · · · · 16. Scindapsus
34. Adult leaf blade pinnatifid; neotropics (Amazonia) 18. Alloschemone
31. Ovary 2–5 locular
35. Seeds fusiform, claviform or lenticular, less than 3 mm long, endosperm present; ovules (2–)3-many per locule; leaf blade entire
36. Placenta basal; seeds fusiform to claviform; leaf blades thickly coriaceous · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 20. Stenospermation
36. Placenta axile; seeds lenticular and flattened, strongly curved; leaf blades
mostly membranous · · · · · · · · · · · · · · · · · · · · · · · 19. Rhodospatha
35. Seeds globose to oblong, 6–22 mm long, the raphe S-shaped; endosperm
absent; ovules 2 per locule; leaf blade variously shaped, often perforated or
pinnatifid or both · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 17. Monstera
27. Flowers unisexual; spadix clearly divided into basal female zone and apical or intermediate male
zone, flowers very rarely in longitudinal rows (Spathicarpa)
37. Spadix fused laterally on both sides to spathe and entirely enclosed by it, forming a septum
dividing the spathe into two chambers, with a single gynoecium on one side and the male
flowers arranged in 2 rows on the other; very small, seasonally dormant plants endemic to
western Mediterranean · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 87. Ambrosina
37. Spadix free or fused to spathe in various degrees but never fused laterally on both sides to
spathe to form two internal chambers with a single gynoecium on one side and the male flowers on the other
38. Stamens of each male flower free or only the filaments connate
39. Spadix never entirely enclosed by spathe in a basal “ kettle “ formed of connate spathe
margins (if spathe margins basally connate then plant never aquatic)
40. Higher order leaf venation parallel-pinnate
41. Upper part of spathe persisting as long as lower part; petiole sheath lacking
ligule; ovary 1–many locular; thecae dehiscing by subapical pores or longitudinal slits; connective usually conspicuously thickened
42. Spathe variously shaped, never campanulate; plants tropical American or
tropical Asian; peduncle usually short, if long then female flowers in
single whorl (Aglaodorum)
43. Plant always terrestrial, rarely aquatic, never climbing or epiphytic;
inflorescences not secreting resin at anthesis; endothecium with cell
wall thickenings; ovary 1 locular or incompletely 2–5 locular; most
tropical Asian (except Homalomena sect. Curmeria)
44. Seed without endosperm, embryo large; ovule 1, placenta basal
or parietal
45. Inflorescence with short peduncle; female flowers in spirals;
stem erect to repent; placenta basal; forest plants · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 72. Aglaonema
45. Inflorescence with long peduncle; female flowers in a single
whorl; stem repent; placenta parietal; on tidal mudflats · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 73. Aglaodorum
44. Seed with copious endosperm, embryo relatively small; ovules
several to many, placenta basal, parietal or axile
K E Y TO G E N E R A
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46. Male flower consisting of solitary stamen overtopped by flask-shaped pistillode;
ovary 1-locular, placenta basal · · · · · · · · · · · · · · · · · · · · · · · · · · · · 46. Furtadoa
46. Male flower consisting of 2–6 stamens, pistillodes absent; ovary incompletely 2–5
locular, placentas parietal and axile · · · · · · · · · · · · · · · · · · · · · 47. Homalomena
43. Plant usually climbing or epiphytic; inflorescences secreting resin from spathe or spadix
at anthesis; endothecium nearly always lacking cell wall thickenings; ovary completely
2–many locular, placenta axile to basal; tropical America · · · · · · · · 45. Philodendron
42. Spathe obconic to campanulate; plants from Southern Africa (naturalized in America and Asia);
peduncle long, sometimes longer than leaves · · · · · · · · · · · · · · · · · · · · 77. Zantedeschia
41. Upper part of spathe marcescent or caducous at anthesis, lower part long-persistent; petiole sheath
with long, marcescent ligule (except most Schismatoglottis spp.); ovary 1-locular; thecae dehiscing
by apical pores, connective not conspicuously thickened
47. Placentas parietal; thecae truncate.
48. Spathe constricted; ovules anatropous to hemianatropous; petiole sheath usually not
ligulate; upper part of spadix usually sterile. · · · · · · · · · · · · · · · 49. Schismatoglottis
48. Spathe not constricted; ovules hemiorthotropous to orthotropous; petiole sheath with long,
marcescent ligule; spadix fertile almost to apex · · · · · · · · · · · · · · · · 50. Piptospatha
47. Placenta basal or basal and apical; thecae truncate or horned
49. Thecae truncate; placenta basal · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 51. Hottarum
49. Thecae horned; placenta basal or basal and apical
50. Stigma smaller than ovary; upper part of spadix sterile with a distinct appendix of
hornless sterile flowers; spathe constricted or not; stamens never excavated apically.
51. Spathe not constricted; male flowers smooth or verrucose; sterile flowers between
male and female flowers flattened · · · · · · · · · · · · · · · · · · 52. Bucephalandra
51. Spathe constricted; male flowers densely tuberculate; sterile flowers between
male and female flowers subcylindric · · · · · · · · · · · · · · · · · 53. Phymatarum
50. Stigma as broad as ovary; upper part of spadix mostly fertile to apex and without a
distinct appendix; spathe not conspicuously constricted; stamens all or mostly excavated apically
52. Stamens all excavated; placenta basal · · · · · · · · · · · · · · · · · · · · 54. Aridarum
52. Two lateral stamens of each male flower excavated and thecae horned, central
stamen truncate and thecae hornless; placentas basal (fertile ovules) and apical
(apparently sterile) · · · · · · · · · · · · · · · · · · · · · · · · · · · · 55. Heteroaridarum
40. Higher order leaf venation reticulate
53. Leaf blade dracontioid, leaf solitary in each growth period
54. Petiole usually aculeate; at least some of the ultimate leaf lobes trapezoid, truncate or shallowly
bifid, veins not forming regular submarginal collective vein on each side
55. Peduncle long; ovary 1-locular · · · · · · · · · · · · · · · · · · · · · · · · · · · · 70. Anchomanes
55. Peduncle very short; ovary 2-locular · · · · · · · · · · · · · · · · · · · · 71. Pseudohydrosme
54. Petiole usually smooth, sometimes rugose but never aculeate; ultimate leaf lobes usually
oblong-elliptic, acuminate, with primary lateral veins forming regular submarginal collective
veins on each side
56. Ovary 1–4-locular; terminal appendix smooth, rugose, rarely verrucose or staminodial
(appendix absent in Amorphophallus margaritifer and A. coudercii) · · · · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 79. Amorphophallus
56. Ovary always 1-locular; terminal appendix staminodial, separated from male zone by
naked axial region · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 80. Pseudodracontium
53. Leaf blade shape of various types but never dracontioid; usually several leaves present
57. Spadix fertile to apex, terminal appendix absent
58. Helophytes with robust, erect stems and an apical crown of sagittate to hastate (rarely trisect) leaves; tropical America · · · · · · · · · · · · · · · · · · · · · · · · · · · · 76. Montrichardia
58. Terrestrial, hemiepiphytic or epiphytic plants, leaf blade variously shaped; tropical Africa.
59. Leaf blade usually with pellucid resin canals (lines or points); plants mostly climbing
hemiepiphytes; spathe boat-shaped, convolute basally; anthers lacking endothecial
thickenings
60. Laticifers absent; flagelliform shoots absent; leaf blade always simple, acute to
rounded at base; ovary 1–3-locular; spadix stipitate or sessile · · · 74. Culcasia
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60. Laticifers present; flagelliform shoots present; leaf blade oblong-lanceolate to
cordate, sagittate, hastate, trifid or laciniate to pinnatifid; ovary 1-locular; spadix
sessile · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 75. Cercestis
59. Leaf blade lacking pellucid resin glands; plants terrestrial; spathe ± fully expanded,
not convolute; anthers with endothecial thickenings
61. Leaf cordate-sagittate or subtriangular, deeply sagittate or trifid, glabrous; spathe
green; spadix entirely free of spathe · · · · · · · · · · · · · · · · · · · 69. Nephthytis
61. Leaf cordate-ovate, minutely hispid abaxially; spathe pure white; female zone of
spadix adnate to spathe · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 78. Callopsis
57. Spadix with ± smooth terminal appendix
62. Laticifers anastomosing; tropical South America
63. Ovary 6- to 9-ovulate; leaf blade trisect to pedatisect; stem a subglobose tuber · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 58. Zomicarpa
63. Ovary 1- to 6-ovulate; leaf blade cordate-sagittate; stem a subglobose tuber or rhizome
64. Appendix slender
65. Stamen connective much prolonged, thread-like; stem tuberous; ovary 1ovulate · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 61. Filarum
65. Stamen connective not at all prolonged; ovary 1-6-ovulate; stem a creeping
rhizome · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 59. Zomicarpella
64. Appendix relatively thick and subcylindric; stem a creeping rhizome; ovary 1ovulate · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 60. Ulearum
62. Laticifers simple; temperate Eurasia and palaeotropics
66. Spadix with zone of sterile flowers between male and female zones, rarely with a
naked axis between female and male zones of spadix (Arum pictum) or with fertile
zones contiguous (Dracunculus)
67. Placenta parietal to subbasal; leaf blade sagittate or hastate · · · · · · · 88. Arum
67. Placenta apical and/or basal; leaf blade variously shaped
68. Placentas basal and apical
69. Male zone of spadix contiguous with female zone; leaf blade pedatifid but
lobes not spirally twisted upwards · · · · · · · · · · · · · · 90. Dracunculus
69. Male zone of spadix separated from female zone by subulate to filiform
sterile organs; leaf blade variously shaped
70. Appendix covered with subulate to setiform sterile flowers; leaf blade
pedatifid, lobes twisting upwards on each side · · 91. Helicodiceros
70. Appendix smooth; leaf blade oblong-lanceolate or sagittate-hastate
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 92. Theriophonum
68. Placenta basal
71. Lower spathe margins free (except Typhonium hirsutum)
72. Infructescence borne above ground level, berries dark red to purple,
pericarp juicy; sterile zone between male and female zones of spadix
relatively long, often partially naked; tropical and subtropical to warm
temperate Asia to Australia · · · · · · · · · · · · · · · · · 93. Typhonium
72. Infructescence borne at or below ground level, berries white to pale
lilac, pericarp firm, not juicy; sterile zone between male and female
zones relatively short and covered entirely with subulate sterile flowers; Turkey, eastern North Africa, Near East, central Asia · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 89. Eminium
71. Lower spathe margins connate for an appreciable distance (entirely free
in Biarum aleppicum)
73. Leaf usually solitary, blade deeply pedatifid to pedatisect; ovary
2–several-ovulate · · · · · · · · · · · · · · · · · · · · · · · 94. Sauromatum
73. Leaves several; blade linear to ovate, elliptic or obovate; ovary 1ovulate
74. Leaf blade broadly elliptic, spathe tube septate · · 95. Lazarum
74. Leaf blade linear, ovate, elliptic-oblong or obovate; spathe tube
not septate · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 96. Biarum
66. Spadix usually without sterile flowers (sometimes present in Arisaema)
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75. Ovary several-ovulate; female zone of spadix free from spathe; spathe without a
transverse septum separating male and female zones.
76. Flowers of both sexes always present in a single inflorescence; male flowers
1-androus; lower spathe margins connate; leaf blade ovate or sagittate · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 86. Arisarum
76. Flowers of both sexes sometimes present in a single inflorescence, but more
often with male and female flowers appearing in separate inflorescences; male
flowers 2–5-androus; lower spathe margins convolute; leaf blade normally trisect, pedatisect or radiatisect, rarely simple and ovate · · · · · 98. Arisaema
75. Ovary 1-ovulate; female zone of spadix adnate to spathe; spathe usually with
transverse septum between male and female zones · · · · · · · · · · · 97. Pinellia
39. Spadix entirely enclosed by spathe in a basal “kettle” formed of connate spathe margins, plants
always helophytic or aquatic
77. Female flowers spirally arranged (pseudo-whorl in Lagenandra nairii, whorled in L. gomezii)
and free; spathe tube “kettle” with connate margins occupying entire spathe tube; spathe blade
usually opening only slightly by a straight ot twisted slit; berries free, opening from base; leaf
ptyxis involute · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 56. Lagenandra
77. Female flowers in a single whorl, connate; spathe tube kettle occupying only lower part of
spathe tube, remainder also with connate margins (except Cryptocoryne spiralis), blade
spreading or twisted; berries connate into a syncarp which opens from the apex; leaf ptyxis
convolute · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 57. Cryptocoryne
38. Stamens of each male flower entirely connate into a distinct synandrium, synandrium rarely reduced
to single stamen (Colletogyne endemic to Madagascar) or stamens free and basally connate with
remote globose thecae (Gorgonidium endemic to Andean South America), or only filaments connate and then stigma stellate and 5–8-lobed (Spathantheum)
78. Laticifers simple
79. Synandria connate, thecae of adjacent synandria encircling pits in the spadix, each pit with
a somewhat prominent upper margin; leaf peltate; Burma to India · · · · · · · · 99. Ariopsis
79. Synandria free; leaf not peltate; Africa, Madagascar or Americas
80. Higher order leaf venation parallel-pinnate or if reticulate then stem a creeping rhizome
and plant from Amazonia (Bognera)
81. Ovules anatropous; primary lateral veins of leaf forming a single marginal vein, no
submarginal collective vein present; plant from tropical America or continental
tropical Africa.
82. Female zone of spadix free; plant from tropical west and central Africa · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 48. Anubias
82. Female zone of spadix entirely adnate to spathe; plant from tropical America.
83. Female flowers each with whorl of several staminodes; higher order leaf
venation strictly parallel-pinnate · · · · · · · · · · · · · · · · · 35. Dieffenbachia
83. Female flowers without staminodes; higher order leaf venation reticulate · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 36. Bognera
81. Ovules orthotropous to hemi-orthotropous; primary lateral veins of leaf forming submarginal collective vein and 1–2 marginal veins; plants from temperate eastern North
America or Madagascar.
84. Giant herbs (to 4m) with massive pseudostem of petiole sheaths; staminodes of
female flower free; Madagascar (also naturalized in Pemba, Zanzibar and
Mascarene Is.) · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 85. Typhonodorum
84. Relatively small herbs (less than 1m) without pseudostem; staminodes of female
flower connate into a cup-like synandrodium; eastern North America · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 84. Peltandra
80. Higher order leaf venation reticulate; stem usually a subglobose tuber, if rhizomatous then
plant Madagascan
85. Madagascan plants; seed lacking endosperm; ovary 1-locular; leaf venation with primary lateral veins forming submarginal collective vein and 1-2 marginal veins on each
side of blade
86. Stamens either completely connate with marginal thecae or only partially connate
by filaments; bisexual flowers often present between male and female zones of
the spadix · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 82. Carlephyton
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86. Stamens completely connate into truncate synandria or synandria reduced to
one stamen
87. Synandria reduced to one stamen, thecae apical on conical filament; spadix
fertile to apex; leaf blade always cordate · · · · · · · · · · · · 83. Colletogyne
87. Thecae apical on a truncate synandrium; spadix appendix present or not; leaf
blade cordate, hastate, trifid, trisect or pedatifid · · · · · · · · 81. Arophyton
85. South American plants; seed with abundant endosperm; ovary with more than 1
locule (except Spathicarpa); leaf venation with primary lateral veins usually forming
single marginal vein on each side, submarginal collective veins usually absent
88. Spadix free or only female zone adnate to spathe
89. Ovules anatropous
90. Ovules 2 per locule; leaf blade entire, linear to subsagittate; spadix, with
terminal appendix of synandrodes · · · · · · · · · · · · · · · · 37. Mangonia
90. Ovules 1 per locule; leaf blade entire, pinnatifid to subdracontioid; spadix
fertile to apex
91. Leaf blade pinnatifid to bipinnatifid or subdracontioid; synandria
elongate; stigma capitate or lobed; staminodes of female flowers free
(connate in Taccarum caudatum) · · · · · · · · · · · · · 38. Taccarum
91. Leaf blade usually pinnatifid, rarely entire; synandria short and domed;
stigma deeply lobed; staminodes of female flowers free or connate
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 39. Asterostigma
89. Ovules orthotropous
92. Styles and synandria elongate; leaf blade pinnatifid or -sect or bipinnatifid
or entire and ± cordate
93. Staminodes in female flowers filiform to subclavate; synandria with
free filament apices or not; leaf blade pinnatifid, pinnatisect or
bipinnatifid · · · · · · · · · · · · · · · · · · · · · · · · · · · 40. Gorgonidium
93. Staminodes in female flowers elongate-triangular; synandria entirely
connate; leaf blade entire, ± cordate · · · · · · 41. Synandrospadix
92. Styles and synandria short and squat or synandria very flat; staminodes
in female flowers obovate or trapezoid; leaf blade pedatisect or subpalmatifid · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 42. Gearum
88. Spadix usually entirely adnate to spathe (male zone free in Spathantheum intermedium)
94. Ovary 6–8-locular; female flowers below, male above; leaf blade entire or pinnately lobed · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 43. Spathantheum
94. Ovary 1-locular; female and male flowers intermixed (2 central rows of
male flowers, 2 outer rows of female flowers); leaf blade entire · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 44. Spathicarpa
78. Laticifers anastomosing
95. Plants climbing hemiepiphytes, sometimes creeping on ground in submature growth; internodes long; berries connate into a syncarp · · · · · · · · · · · · · · · · · · · · · · · 67. Syngonium
95. Plants terrestrial or geophytic, rarely aquatic, not climbing; internodes very short; berries free
from each other
96. Spadix without an appendix (present in Hapaline appendiculata, included here, occasionally absent in Colocasia esculenta, excluded here)
97. Ovary completely to incompletely 2- to several-locular with deeply intrusive parietal
placentas (1-locular with basal placenta in Jasarum, Scaphispatha and a few species
of Caladium and Xanthosoma); neotropical plants
98. Helophytes or terrestrial; leaf blade ovate, sagittate to hastate or pedatifid
99. Pollen shed in tetrads; style usually laterally thickened or expanded into a
diaphanous mantle; leaf blade rarely peltate, sometimes trifid or -sect, or
pedatifid or -sect
100. Spathe tube subglobose, inflated; female zone of spadix free; styles
normally discoid (laterally swollen) and coherent (except Xanthosoma
plowmanii); synandrodes (sterile flowers) between male and female
flowers well-developed, ± prismatic · · · · · · · · · · · 65. Xanthosoma
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100. Spathe tube narrow, elongate; female zone of spadix mostly adnate to
spathe; stylar region thin, spreading, diaphanous, mantle-like; synandrodes (sterile flowers) betweeen male and female flowers usually
irregular or fungiform, not prismatic · · · · · · · · · · 66. Chlorospatha
99. Pollen shed in monads; stylar region not laterally expanded; leaf blade usually peltate, rarely trisect, never pedatifid or -sect
101. Spathe tube always convolute; stylar region as broad as ovary (Caladium
paradoxum has discoid, coherent stylar regions); synandrodes (sterile
flowers) between male and female flowers well-developed, prismatic;
placentas 1–2(–3), parietal; seeds several (rarely 1–2) · · · 63. Caladium
101. Spathe tube gaping widely at anthesis; style much narrower than ovary;
synandrodes (sterile flowers) lacking, male and female zones contiguous; placenta 1, basal; seed solitary · · · · · · · · · · · 62. Scaphispatha
98. Submerged aquatics; leaf blade linear · · · · · · · · · · · · · · · · · · · · · 64. Jasarum
97. Ovary clearly 1-locular, placentas not intrusive; palaeotropical plants
102. Ovules more than 1; leaf blade peltate
103. Female flowers with staminodes; spathe not constricted; stem trunk-like or
creeping · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 101. Steudnera
103. Female flowers without staminodes; spathe with 1 or 2 constrictions; stem
tuberous, producing erect or spreading stolons bearing small tubercles
covered in hooked scales · · · · · · · · · · · · · · · · · · · · · · 102. Remusatia
102. Ovule solitary; leaf blade not peltate · · · · · · · · · · · · · · · · · · · · 68. Hapaline
96. Spadix with an appendix (occasionally absent in Colocasia esculenta); palaeotropical
plants
104. Leaf blade pedatisect to radiatisect; female flowers each with several large staminodes · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 100. Protarum
104. Leaf blade entire or pinnatifid; female flowers without staminodes (except single
small ones in Colocasia esculenta)
105. Placentas parietal; ovules many; leaf blade always entire · · · 103. Colocasia
105. Placenta basal; ovules few; leaf blade entire or pinnatifid · · · 104. Alocasia
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THE GENERA OF ARACEAE
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26 D E S C R I P T I O N S O F T H E T R I B E S A N D G E N E R A O F A R A C E A E
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I. Subfamily Gymnostachydoideae
Subfamily Gymnostachydoideae Bogner & Nicolson in
Willdenowia 21: 37 (1991).
Laticifers absent; stem a short rhizome; leaves distichous,
bifacial (dorsiventrally flattened), linear, not differentiated
into blade and petiole, primary veins parallel; flowering shoot
a complex synflorescence consisting of 3–6(7), short, perennating floral sympodia, borne on an erect peduncular axis,
each sympodium axillary to a bract and composed of numerous inflorescences; spathe inconspicuous; spadix
long-stipitate; flowers bisexual, perigoniate, 2-merous; tepals
4, fornicate, stamens 4, free, thecae dehiscing by longitudinal slit, pollen monosulcate; ovary 1-locular, ovule 1,
orthotropous, placenta apical, stigma small; berries deep
blue, long-exserted beyond tepals; seed obovoid, testa absent
at maturity, embryo axile, endosperm copious.
C
1. Gymnostachys
Gymnostachys R. Brown, Prodr. 337 (1810). TYPE: G.
anceps R. Brown
HABIT: acaulescent herbs, stem a short, thick subterranean
rhizome. LEAVES: distichous, bifacial (dorsiventrally flattened), somewhat plicate, linear, not differentiated into blade
and petiole, margins erose-serrate; midrib not differentiated,
primary lateral veins parallel, somewhat prominent, higher
order venation parallel. INFLORESCENCE: borne on a long
scape, terminating in 3–6(–7), short, perennating floral sympodia separated from each other by a distinct peduncular
axis, each sympodium composed of several spadices and
borne axillary to a leaf-like bract. SCAPE: subequal to leaves,
alate on each side, margins erose-serrate. SPATHE: a simple,
short, keeled, inconspicuous bract, ± alternating with the
short, linear-lanceolate, 2-keeled prophylls of each article of
the floral sympodium. SPADIX: short- to long-stipitate, cylindric, many-flowered, erect in flower, pendent in fruit.
FLOWERS: bisexual, perigoniate, often somewhat distant;
tepals 4, ± as long as wide, fornicate, imbricate. STAMENS:
4, free, filaments somewhat flattened, anthers short, connective slender, thecae ellipsoid, dehiscing by a longitudinal
slit, connective inconspicuous. POLLEN: monosulcate, ellipsoid, medium-sized (mean 31 µm., range 30–33 µm.), exine
foveolate to slightly fossulate, apertural exine fossulate-verrucate. GYNOECIUM: ovary oblong, 1-locular, ovule 1,
orthotropous, funicle very short, placenta apical, stylar
region shortly attenuate, stigma small, subhemispheric.
BERRY: ellipsoid, deep blue, apiculate, 1-seeded, strongly
projecting beyond tepals. SEED: ellipsoid to obovoid, testa
absent at maturity, embryo axile, ± elongate, endosperm
copious. See Plates 1, 107A.
CHROMOSOMES: 2n = 48.
DISTRIBUTION: 1 sp.; Australia (Queensland, New South
Wales).
ECOLOGY: southern temperate to subtropical or rarely
tropical rainforest; understorey plant in moist hardwood
forests, most common on cool southerly slopes and in cool
moist gullies.
ETYMOLOGY: Greek gymnos (naked) and stachys (spike).
TAXONOMIC ACCOUNTS: Engler (1905), Shelton (1980),
Elliot & Jones (1990), Hnatiuk (1990), Hay (1993c).
II. Subfamily Orontioideae
C
Subfamily Orontioideae Mayo, Bogner & P.C. Boyce,
Genera of Araceae p. 346 (1997).
Laticifers absent (except Orontium); helophytes, stem a stout,
erect rhizome, continuation shoot in axil of last leaf preceding spathe; petiole not geniculate apically, sheath long; leaf
blade entire, oblong-elliptic, higher order venation reticulate; flowers bisexual, perigoniate; tepals free, fornicate,
stamen with distinct filament, anther terminal, connective
slender, thecae dehiscing by longitudinal slit, pollen monosulcate; ovary ± immersed in spadix axis; seed testa smooth,
thin or absent at maturity, embryo large, endosperm very
sparse to absent.
2. Orontium
C
Orontium L., Sp. Pl. 324 (1753). TYPE: O. aquaticum L.
SYNONYMS: Amidena Adanson, Fam. 2: 470 (1763);
Aronia J. Mitchell, Diss. Gen. Pl. 28 (1769), nom. rej.
1. Gymnostachys
Laticifers present, simple, articulated. HABIT: seasonally dormant, aquatic herbs, continuation shoot of stem sympodium
arising in axil of last foliage leaf of each article and beginning with a foliage leaf rather than a cataphyll, rhizome
short, erect, buried deep in soil. LEAVES: several. PETIOLE:
ORONTIOIDEAE : ORONTIUM
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D
A
C
H
J
K
L
E
B
G
F
M
Plate 1. Gymnostachys. A, habit × 1/6; B, base of plant × 2/3; C, detail of leaf venation showing erose-serrate midrib and margin x 5;
D, cross-section of leaf × 5; E upper part of inflorescence × 1/3; F, detail of peduncle showing erose margin × 5; G, spadix × 1; H, detail
of spadix × 10; J, tepal, side view × 20; K, flower with perigone removed × 20; L, gynoecium, longitudinal section × 20; M, berry × 2.
Gymnostachys anceps: A, Dransfield s.n. (Kew slide collection); B, Cunningham 337 (K); C–D, Forster 4851 (K); E, Brown s.n. (K); F–M,
Covery 10432 (Kew spirit collection 29047.718).
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THE GENERA OF ARACEAE
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H
J
C
A
F
D
B
E
G
Plate 2. Orontium. A, habit × 1/5; B, habit × 2/3; C, detail of leaf venation × 5; D, detail of spadix × 5; E, flower × 10; F, stamen, adaxial view × 10; G, gynoecium, longitudinal section × 10; H, fruit × 4; J, fruit, longitudinal section × 4. Orontium aquaticum: A, Boyce s.n.
(Kew slide collection); B–C, Curtis s.n. (K); D–G, Mayo s.n. (Kew spirit collection 46576) (K); H, Hooker s.n. (K); J, Bogner 1896 (Kew
spirit collection 56428).
ORONTIOIDEAE : ORONTIUM
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ETYMOLOGY: ancient Greek orontion referred to an
unknown plant used for treating jaundice; according to some
authors named after the River Orontes in Syria.
TAXONOMIC ACCOUNTS: Huttleston (1953), Klotz (1991,
1993).
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3. Lysichiton
Lysichiton Schott in Oesterr. bot. Wochenbl. 7: 62 (1857).
TYPE: L. camtschatcensis (L.) Schott (“camtschatcense”;
Dracontium camtschatcense L.)
SYNONYMS: Arctiodracon A. Gray in Mem. Amer. Acad.
Arts, ser. 2, 6: 408 (1859); [Lysichitum Schott in Oesterr. bot.
Wochenbl. 7: 62 (1857), orth. var.]
2. Orontium
terete, sheath long. BLADE: oblong-elliptic, held above water
surface or floating on it; primary lateral veins arising at base
of blade, arcuately ascending and running into apex, secondary laterals inconspicuous and parallel to primaries, higher
order venation transverse-reticulate. INFLORESCENCE: 1–2
in each floral sympodium. PEDUNCLE: absent, spadix supported on elongated stipe. SPATHE: a short, inconspicuous,
simple bract, inserted at point of attachment of inflorescence to rhizome, enclosing young spadix, later separated
from it and disintegrating. SPADIX: held above water level,
conical, slender, flowering acropetally, golden yellow,
peduncle-like stipe very long, often partly submerged, greenish to red-brown with white, swollen apical part. FLOWERS:
bisexual except for some male flowers at spadix apex,
perigoniate, tepals 6, sometimes 4, short, about as long as
wide, fornicate, subtruncate, irregularly imbricate. STAMENS:
6, sometimes 4, free, filaments flattened, connective slender,
thecae ellipsoid, dehiscing by broad apical slit. POLLEN:
monosulcate, ellipsoid, large (mean 64 µm., range 55–73
µm.), exine densely foveolate-fossulate. GYNOECIUM: ovary
depressed-globose, broader than long, 1-locular, ovule 1,
hemianatropous, held horizontally, funicle short, placenta
basal, stylar region ± absent, stigma small, subsessile, discoid-hemispheric. BERRY: depressed-globose, green,
1-seeded, partially immersed in spadix axis. SEED: ± globose, testa thin, smooth, ± transparent, decaying at maturity,
raphe conspicuous in furrow-like depression, hilum reddish, embryo large, almost globose to depressed-globose,
with a small internal cavity situated below the hilum, outer
cell layers green, plumule well-developed with 1(–2) filiform
leaf primordia, endosperm absent. See Plates 2, 107B.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 1 sp.; temperate E. North America:– USA
(Alabama, Carolinas, Connecticut, Delaware, Florida, Georgia,
Kentucky, Louisiana, Maryland, Massachusetts, Mississippi,
New Jersey, New York, Pennsylvania, Rhode Is., Tennessee,
Virginia, West Virginia).
ECOLOGY: temperate wetlands, occurring from sea level to
900m alt.; partly submersed aquatic plant growing in open or
partially shaded swamps, marshes, lakes and ponds, in dense
stands or scattered colonies.
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THE GENERA OF ARACEAE
HABIT: large herbs with thick, hypogeal rhizome. LEAVES:
numerous. PETIOLE: thick, flattened to deeply sulcate, sheath
long. BLADE: becoming large, ovate-elliptic to ovate-oblong;
primary lateral veins pinnate, running into inconspicuous
marginal vein, higher order venation ± regularly transversereticulate between primaries. INFLORESCENCE: solitary,
appearing just before or with the leaves in early spring.
PEDUNCLE: absent, spadix supported on elongated stipe.
SPATHE: marcescent, inserted at the point of attachment of
spadix stipe to rhizome, cucullate to boat-shaped, lower part
narrowly convolute and clasping spadix stipe, blade
expanded, ovate-elliptic, white or yellow. SPADIX: subcylindric, subacute at apex, stipe extremely elongated. FLOWERS:
bisexual, perigoniate; tepals 4, cucullate, imbricate. STAMENS:
4, free, filaments oblong, flattened, connective slender, thecae
ellipsoid, dehiscing by longitudinal slit. POLLEN: monosulcate,
ellipsoid, medium-sized (mean 40 µm., range 38–43 µm.),
exine reticulate. GYNOECIUM: elongate-ovoid, attenuate apically, ovary immersed in spadix axis, 2–locular or
incompletely 2-locular, ovules 1–2 per locule, orthotropous,
broad, conoid, funicle very short and thick, placenta axile,
thick, stylar region attenuate, longer than tepals, stigma discoid-hemispheric. BERRY: ellipsoid, mostly 2-seeded, green,
decaying or stylar portion breaking off with perigone at maturity to expose seeds embedded in spadix axis. SEED: ±
ellipsoid, somewhat compressed, testa smooth, embryo large,
ellipsoid, endosperm nearly absent, present only as a single
cell layer. See Plates 3, 107C.
3. Lysichiton
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H
J
G
K
L
D
M
B
E
F
A
C
Plate 3. Lysichiton. A, flowering habit × 1/3; B, leaf × 1/3; C, detail of junction of spathe, stipe and rhizome, longitudinal section × 2; D,
peduncle surrounded by spathe base, transverse section × 2; E, flowering habit × 1/10; F, vegetative and fruiting habit × 1/8; G, detail of spadix
× 3; H, flower × 6; J, flower, longitudinal section × 6; K, seed, adaxial view × 3; L, seed, side view × 3; M, seed, abaxial view × 3. Lysichiton
americanus: A-D, Cult. Kew 1969–18002; E, Ballard 364 (Kew slide collection); F, Townsend 87/142 (Kew slide collection); G–J, Cult. Jodrell
(Kew spirit collection 29047.78 & 29047.764); K–M, Townsend 87/127 (Kew spirit collection 51789).
O R O N T I O I D E A E : L Y S I C H I TO N
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26a Tribes & Genera Acro 17/7/97 16:40 Page 96
CHROMOSOMES: 2n = 28.
DISTRIBUTION: 2 spp.; temperate E. Asia and W. North
America:– Canada (British Columbia), Japan, Russian Far East
(Kamchatka, Kuril Is., Okhotsk, Sakhalin, Udsk), USA (Alaska,
California, Idaho, Montana, Oregon, Washington).
ECOLOGY: temperate wetlands; helophytes, in swamps and
wet woodlands.
ETYMOLOGY: ancient Greek lysis (free) and chiton (tunic).
TAXONOMIC ACCOUNTS: Krause (1908), Hultén & St. John
(1931,1956), Huttleston (1953, 1955), Nicolson (1981).
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4. Symplocarpus
Symplocarpus R.A. Salisbury ex Nuttall in W. Barton, Gen.
1: 105 (1817), (see Taxon 29: 601, Phytologia 72: 80–92)
nom. cons. TYPE: S. foetidus (L.) Nuttall (Dracontium
foetidum L.)
SYNONYMS: Ictodes Bigelow in Amer. Med. Bot. 2: 41
(1818); Spathyema Rafinesque, Fl. Tell. 4: 13 (1838, “1836”);
[Symplocarpos J.A. Schultes & J.H. Schultes, Mant. 3: 16
(1827), orth. var.]
HABIT: fairly large, seasonally dormant herbs, rhizome thick,
erect with thick roots. LEAVES: few. PETIOLE: fairly broad, sulcate, sheath short. BLADE: subcordate- to cordate-ovate;
primary lateral veins pinnate, arching towards apex, running
into inconspicuous marginal vein, secondary laterals and
higher order venation reticulate to transverse-reticulate.
INFLORESCENCE: 1–2 in each floral sympodium, appearing
before or with leaves. PEDUNCLE: only shortly exserted above
ground. SPATHE: thick, boat-shaped or conchiform, lower
part convolute, upper part somewhat to widely gaping, apex
2-keeled, rostrate, curving forwards. SPADIX: stipitate, subglobose, hidden within spathe. FLOWERS: bisexual,
perigoniate; tepals 4, fornicate, imbricate. STAMENS: 4, free,
filaments flattened, connective slender, thecae oblong, dehiscing by longitudinal slit. POLLEN: monosulcate, ellipsoid,
medium-sized (mean 33 µm.), exine reticulate, apertural exine
4. Symplocarpus
96
THE GENERA OF ARACEAE
coarsely verrucate. GYNOECIUM: ovary somewhat immersed
in spadix axis, 1-locular, ovule 1, orthotropous, funicle very
short, placenta apical-parietal, stylar region long-attenuate,
stigma punctate-discoid. BERRY: tepals and style persistent to
ripe fruiting stage, seed and base of berry immersed in spongy
spadix axis, infructescence ± globose. SEED: globose, testa
thin, smooth, embryo globose, endosperm very sparse, only
a single cell layer thick. See Plates 4, 107D.
CHROMOSOMES: 2n = 30, 60 (28).
DISTRIBUTION: 3 spp.; temperate E. Asia and E. North
America:– Canada (New Brunswick, Nova Scotia, Quebec,
Ontario), China, Japan, Korea N. & S., Russian Far East, USA
(Connecticut, Delaware, Indiana, Illinois, Iowa, Maine,
Maryland, Massachusetts, Michigan, Minnesota, New
Hampshire, New Jersey, New York, North Carolina, Ohio,
Pennsylvania, Rhode Is., Tennessee, Virginia, West Virginia,
Wisconsin).
ECOLOGY: temperate damp woodlands, rarely open wetlands, from near sea level to ca. 900m. alt.; usually in shaded
sites, frequent near water courses; S. foetidus and S. renifolius
flower in early spring before the leaves appear and fruit in
the summer of the same year; S. nipponicus flowers after the
leaves appear and the fruits ripen in the following spring.
ETYMOLOGY: Greek syn- (together), -plo (folded) and karpos
fruit); refers to immersion of gynoecia and fruits in spadix axis.
TAXONOMIC ACCOUNTS: Huttleston (1953), Lee (1985).
III. Subfamily Pothoideae
Subfamily Pothoideae Engler in Nova Acta Acad. Leopold.Carol. 39: 140 (1876).
Laticifers absent; stem usually aerial; petiole geniculate apically; higher order leaf venation reticulate; spathe simple,
spreading to reflexed, not enclosing spadix; flowers bisexual,
perigoniate; stamen filament distinct, anther terminal, thecae
dehiscing by longitudinal slit, connective inconspicuous.
C
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M
D
B
F
L
K
J
C
E
G
A
H
Plate 4. Symplocarpus. A, habit showing vertical rhizome, longitudinally sectioned × 2/3; B, flowering habit × 1/3; C, leaf × 2/3; D, detail
of leaf venation × 5; E, inflorescence, nearside half of spathe removed × 1; F, detail of spadix × 3; G, flower × 10; H, flower, nearside tepals
removed × 10; J, gynoecium, longitudinal section × 10; K, infructescence × 1; L, seed, side view × 2; M, habit × 1/3. Symplocarpus foetidus:
A, Herb Gray 7/82 (K) & Cult. Kew 1969–18003 (Kew spirit collection 51367); B, Cult. Kew 1969–18003 (Kew slide collection); C–D, W.D.
s.n. (K); E–L, Cult. Kew 1969–18003 (Kew spirit collection 51367, 51616 & 55681); S. renifolius: M, Furuse 8737 (K).
ORONTIOIDEAE : SYMPLOCARPUS
97
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Tribe Potheae
C
Tribe Potheae Engler in Nova Acta Acad. Leopold.-Carol. 39:
140 (1876, Pothoeae).
Laticifers absent; shrubby climbing herbs with tough woody
stems, main shoot monopodial, flowering shoots axillary or
infra-axillary; leaves distichous; petiole sheath long and often
broad, flattened and apically auriculate (reduced in
Pedicellarum and Pothos series Goniuri); flowers bisexual,
perigoniate, (2–)3-merous; tepals (4–)6, stamens 6, free, pollen
monosulcate; ovules 1 per locule, anatropous, stigma sessile,
usually umbonate; embryo large, endosperm absent.
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5. Pothos
Pothos L., Sp. Pl. 968 (1753). TYPE: P. scandens L.
SYNONYMS: Tapanava Adanson, Fam. 2: 470 (1763);
Batis Blanco, Fl. Filip. 791 (1837); Goniurus Presl, Epim.
Bot. 244 (1851, “1849”); [Potha O. Kuntze, Rev. Gen. 2: 742
(1891), orth.var.]
Trichosclereids occasionally present. HABIT: climbing herbs,
stems rather woody, lower branches rooting, upper ones
free and hanging, nodes rarely bearing short, clustered spines
(P. armatus), buds of lateral shoots sometimes perforating the
leaf sheath or ± infra-axillary. LEAVES: distichous, juvenile
plants of some species with shingle form. PETIOLE: geniculate (articulate) apically, either broad, completely flattened
and usually auriculate apically, or morphology normal with
a long sheath, sometimes sheath reduced to a pair of hyaline
ridges (series Goniuri). BLADE: linear-lanceolate to ovate or
elliptic, sometimes oblique; primary lateral veins either mostly
arising near base of blade, long arcuate, and running into
marginal vein near apex, or primary lateral veins pinnate,
weakly differentiated, forming submarginal collective vein,
1–2 marginal veins also present, higher order venation reticulate in all types. INFLORESCENCE: axillary or infra-axillary,
solitary or forming short branching systems of several inflo-
5. Pothos
98
THE GENERA OF ARACEAE
rescences, bearing 4–6 (sometimes more, e.g. P. insignis)
rigid, coriaceous cataphylls at the base. PEDUNCLE: short to
long, sometimes reflexed. SPATHE: ovate to linear, rarely
very long (P. mirabilis). SPADIX: globose, ovoid, cylindric,
ellipsoid or obovoid, sessile to long-stipitate, densely or laxly
flowered. FLOWERS: bisexual, perigoniate; tepals 4–6, usually fornicate, free or partially to completely connate (e.g. P.
rumphii). STAMENS: 4–6, free, filaments oblong, flattened,
connective slender, thecae ellipsoid, dehiscing by slit.
POLLEN: monosulcate, ellipsoid-oblong, small (mean 21 µm.,
range 16–25 µm.), exine foveolate to reticulate or subrugulate, muri psilate or minutely tuberculate. GYNOECIUM:
ovary ovoid-oblong or depressed, (2?–)3-locular; ovules 1
per locule, anatropous, funicle short, placenta axile at base
of septum, stylar region sometimes as broad as ovary, stigma
discoid-hemispheric to umbonate. BERRY: ellipsoid to ovoid,
1–3-seeded, red. SEED: ellipsoid, testa smooth, embryo large,
endosperm absent. See Plates 5, 108A.
CHROMOSOMES: 2n = 24, 36.
DISTRIBUTION: ca. 70 spp.; south and southeast Asia,
Australasia, Malagasy region, Malay Archipelago:– Australia
(New South Wales, Queensland), Bangladesh, Brunei,
Burma, Cambodia, China (Guandong, Guangxi, Guizhou,
Hainan, Hunan, Sichuan, Taiwan, Yunnan), Comores Is.,
India, Indonesia (Borneo, Irian Jaya, Java, Moluccas,
Sulawesi, Sumatra), Japan (Ryukyu Is.), Laos, Madagascar,
Malaysia (Borneo, Peninsula), Nepal, Papua New Guinea,
Philippines, Solomon Is., Sri Lanka, Thailand, Vanuatu,
Vietnam.
ECOLOGY: tropical humid forest; usually climbing hemiepiphytes often in regrowth forest, rarely on rocks.
NOTES: Engler (1905) recognized 2 sections:– sect. Pothos
(with 4 series), sect. Allopothos (with 3 series).
ETYMOLOGY: modified spelling of a Sinhalese vernacular
name “potha”; P. scandens is still known as “pota-wel” in
Sri Lanka.
TAXONOMIC ACCOUNTS: Engler (1905), Sivadasan (1982),
Nicolson (1988a), Sivadasan, Mohanan & Rajkumar (1989),
Boyce & Poulsen (1994), Boyce & Nguyen (1995).
26a Tribes & Genera Acro 17/7/97 16:41 Page 99
B
C
D
E
A
F
M
J
S
H
P
R
G
N
K
L
Q
Plate 5. Pothos. A, habit × 2/3; B, detail of leaf venation × 5; C, detail of spadix × 10; D, gynoecium, transverse section × 10; E, juvenile
habit × 2/3; F, detail of spadix × 6; G, portion of flowering stem × 2/3; H, detail of petiole venation × 5; J, detail of leaf venation × 5; K, flowering shoot showing developing flagelliform shoot × 2/3; L, infructescence × 1; M, flower, top view × 10; N, flowering shoot × 2/3; P, detail
of leaf venation × 5; Q, infructescence × 1; R, flower, top view × 10; S, gynoecium, longitudinal section × 10. Pothos beccarianus: A–D, Sumbing
Jimpin SAN 110325 (K); P. motleyanus: E, Burbidge s.n. (K); P. barberianus: F, UNESCO (Kostermans) 192 (K & Kew spirit collection 58012);
P. scandens: G–J, Cult. Kew (Kew spirit collection 19158); Soedarsono 280 (K); P. junghuhnii: K–M, Warnham s.n. Cult. Kew (K); P. rumphii:
N–S, Forman 240 (K); Sands s.n., Cult Kew 1970–02267 (Kew spirit collection 29047.171).
P OT H O I D E A E : POT H O S
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6. Pedicellarum
Pedicellarum M. Hotta in Acta Phytotax. Geobot. 27 (34): 61
(1976). TYPE: P. paiei M. Hotta
HABIT: climbing, shrubby herb, branches distichously leaved,
branching from below the nodes, juvenile shoots with shingle form, flowering branches producing flagelliform shoots.
LEAVES: several. PETIOLE: sometimes pubescent in young
leaves, geniculate at apex, sheathed for the most part.
BLADE: lanceolate to narrowly elliptic (nearly orbicular in
shingle form), acuminate; primary lateral veins pinnate, forming submarginal collective vein, 1–2 distinct marginal veins
also present, higher order venation reticulate. INFLORESCENCE: arising below the nodes, bearing several short
cataphylls at base of peduncle. PEDUNCLE: shorter than
spadix, subequal to or longer than petiole, very slender.
SPATHE: small, fully expanded, ovate-cordate, membranaceous. SPADIX: sparsely and very laxly flowered,
long-stipitate, axis flexuose, minutely hispid-papillose. FLOWERS: bisexual, perigoniate, on short pedicels, receptacle large
and conspicuous; tepals connate, forming cup-like structure.
STAMENS: 6, free, filaments broad, flattened, connective slender, thecae ellipsoid, latrorse, dehiscing by longitudinal slit.
POLLEN: monosulcate, ellipsoid-oblong, small (mean 17
µm.), exine reticulate, muri minutely tuberculate. GYNOECIUM: obpyramidal, excavated at apex, ovary 3-locular,
ovules 1 per locule, anatropous, placenta axile at base of septum, stigma sessile, umbonate. BERRY: obovoid, 1–3-seeded,
red. SEED: compressed-ellipsoid, testa smooth, thin, embryo
large, endosperm absent. See Plates 6, 108B.
CHROMOSOMES: unknown.
DISTRIBUTION: 1 sp.; Indonesia (Borneo), Malaysia (Borneo).
ECOLOGY: tropical humid forest; climbing hemiepiphyte.
NOTES: Appears closely related to Pothos series Goniuri,
in which the spadix also has a slender axis and the flowers
are distant.
ETYMOLOGY: Latin pes, pedis (foot), -ella (diminutive) and
Arum; refers to the unique character of pedicellate flowers.
TAXONOMIC ACCOUNTS: Nicolson (1984b).
7. Pothoidium
100
THE GENERA OF ARACEAE
6. Pedicellarum
7. Pothoidium
Pothoidium Schott, Aroideae 6: 26, t. 57 (1857) & in Oesterr.
bot. Wochenbl. 7: 70 (1857). TYPE: P. lobbianum Schott
HABIT: climbing herb, stems somewhat woody, flowering
branches free and hanging. LEAVES: distichous, many. PETIOLE: oblong, entirely flattened, resembling blade, venation
parallel, joined to blade by constricted articulation. BLADE:
much shorter than petiole, triangular-lanceolate; midrib
absent, no primary veins differentiated, veins parallel, running into apex. INFLORESCENCE: several to many, borne in
a terminal branching system, lower inflorescences axillary
to a foliage leaf, upper ones either subtended by cataphyll
or without subtending leaf. PEDUNCLE: peduncular axis
slender, composed of one to several internodes, sometimes
subtended by a prophyll, sometimes also bearing a cataphyll ± halfway up. SPATHE: occurrence irregular, often
absent, linear-lanceolate, widely spreading, margins usually revolute. SPADIX: apparently often functionally
unisexual, cylindric, sessile to long-stipitate when subtended
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D
E
B
A
C
J
H
G
F
Plate 6. Pedicellarum. A, habit × 2/3; B, petiole × 3; C, detail of petiole base × 5; D, detail of leaf venation × 5; E, juvenile shingle habit
× 1; F, inflorescence × 2; G, flower × 10; H, gynoecium, transverse section × 10; J, infructescence × 2. Pedicellarum paiei: A–D, F, Paie SAN
16354 (K, L); E, Boyce 782 (K & Kew slide collection); G, Lassan SAN 107216 (K); H, Church et al. 303 (A, Kew spirit collection 58609); J,
Lee S 54080 (L).
P OT H O I D E A E : P E D I C E L L A R U M
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C
D
B
E
G
F
A
Plate 7. Pothoidium. A, habit × 2/4; B, detail of leaf blade and petiole venation × 2; C, infructescence × 1; D, detail of basal portion of
spadix × 5; E, flower, top view × 10; F, flower, nearside tepal removed × 10; G, gynoecium, longitudinal section. Pothoidium lobbianum:
A–B, de Vogel 3866 (K); C, Loher 7047 (K); D, Merrill 2293 (K & Kew spirit collection 58025); E–G, Herb. Lugd. Bat. (K).
102
THE GENERA OF ARACEAE
26a Tribes & Genera Acro 17/7/97 16:42 Page 103
by spathe. FLOWERS: apparently usually unisexual, sometimes bisexual, perigoniate, male flowers with well
developed anthers and apparently sterile ovary, female
flowers with large fertile ovary and lacking stamens; tepals
6, fornicate, membranaceous. STAMENS: 3–6, free, number
often varying on single spadix, filaments elongated and
overtopping perigone at anthesis, oblong-triangular, flattened, connective slender, thecae short, ellipsoid, dehiscing
by broad slit. POLLEN: monosulcate, ellipsoid-oblong,
medium-sized (mean 26 µm.), exine reticulate with psilate
muri, apertural exine shallowly fossulate or verrucate.
GYNOECIUM: broadly ovoid to subglobose or obovoid,
ovary 1-locular, ovule 1, anatropous, funicle short, placenta
subbasal, stylar region attenuate, stigma discoid-hemispheric. BERRY: ellipsoid to ovoid, apiculate (stigma
remnant), prominently exserted when mature, red. SEED:
ellipsoid, testa smooth, embryo large, endosperm absent.
See Plate 7.
CHROMOSOMES: 2n = 24.
DISTRIBUTION: 1 sp.; southeast Asia, Malay Archipelago:–
China (Taiwan), Indonesia (Moluccas, Sulawesi, Sumatra),
Philippines.
ECOLOGY: tropical humid forest; climbing hemiepiphyte.
ETYMOLOGY: Pothos and Greek -idion (special); implies a
plant distinct from Pothos.
TAXONOMIC ACCOUNTS: Engler (1905).
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Tribe Anthurieae
Tribe Anthurieae Engler in Nova Acta Acad. Leopold.Carol. 39: 140 (1876).
rotting to a fibrous mass (net-fibrous), sometimes completely disappearing. PETIOLE: geniculate apically
(geniculum rarely well below blade, e.g. A. oerstedianum),
variously shaped in cross-section, sheath long in juvenile
(monopodial) leaves, very short in sympodial leaves.
BLADE: small to very large (exceeding 2m), usually coriaceous, more rarely membranaceous or stiff and brittle,
extraordinarily variable in shape, linear to orbicular in outline, rarely peltate, entire to trifid or trisect, or pedatifid or
subpalmatifid, or pedatisect to radiatisect, rarely the lobes
or segments themselves pinnately lobed, blade base cuneate
to cordate, sagittate or hastate; primary lateral veins pinnate
or more rarely all arising at the base, usually forming one
or more submarginal collective veins, basal ribs often present in cordate leaves, higher order venation reticulate.
FLOWERING BRANCHES: sympodial units usually comprising one 2-keeled prophyll, one 1-keeled cataphyll, one
foliage leaf and terminal inflorescence. INFLORESCENCE:
always solitary. PEDUNCLE: usually rather elongated, rarely
short. SPATHE: usually persistent, sometimes marcescent
or deciduous, usually linear to linear-lanceolate, more rarely
elliptic to ovate, broadly cordate to suborbicular, erect,
spreading or reflexed. SPADIX: sessile to long-stipitate, usually cylindric to conic, more rarely clavate, rarely globose,
very short to very long (over 1m). FLOWERS: bisexual,
perigoniate; tepals 4, fornicate, in 2 decussate whorls.
STAMENS: 4, free, filaments somewhat flattened, usually
equalling tepals at anthesis, sometimes exceeding them,
anthers short, connective slender, thecae ovate to oblongovate, dehiscing by longitudinal slit. POLLEN: forate (most
often 3–4 pores), more rarely diporate, rarely inaperturate
(sect. Polyphyllium), spherical to subspheroidal, small
(mean 22 µm., range 14–29 µm.), exine foveolate to retic-
Laticifers absent; climbers, hemiepiphytes, epiphytes, lithophytes or terrestrial herbs, sympodial units of stem each
normally composed of prophyll, cataphyll, foliage leaf, inflorescence (often aborted); petiole of sympodial leaves with
very short sheath, geniculate apically; primary lateral veins
pinnate (rarely all arising at petiole insertion) in blade of
entire leaves and in lobes of compound leaves, usually forming one or more submarginal collective veins; spathe usually
simple, spreading, reflexed or erect, linear to elliptic or
ovate; flowers bisexual, perigoniate; tepals 4, fornicate, stamens 4, free, pollen usually forate (periporate) with 3–4
pores, more rarely diporate, rarely inaperturate (sect.
Polyphyllium); ovary 2-locular, ovules 1–2 (rarely more) per
locule, anatropous to campylotropous, placenta axile-subapical; mature berries exserted and usually dangling; seed
often sticky, endosperm copious.
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8. Anthurium
Anthurium Schott, in Wiener Z. Kunst 1829 (3): 828
(1829). LECTOTYPE: A. acaule (Jacquin) Schott (Pothos
acaulis Jacquin, see Britton & Wilson, Sci. Surv. Porto Rico
5: 128. 1923).
SYNONYMS: Podospadix Rafinesque, Fl. Tell. 4: 821
(1838, “1836”); Strepsanthera Rafinesque, Fl. Tell. 4: 13 (1838,
“1836”).
HABIT: evergreen herbs, stem erect, creeping, or short- to
long-climbing, rarely rhizomatous, internodes very short
(plant rosulate) to elongated. LEAVES: prophylls and cataphylls usually ± persistent, entire (membranaceous) or
8. Anthurium
P OT H O I D E A E : A N T H U R I U M
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C
D
F
E
B
A
H
J
G
Plate 8 (i). Anthurium. A, leaf × 1/2; B, leaf × 1/2; C, leaf × 1/2; D, leaf × 1/2; E, leaf × 1/2; F, leaf × 1/2; G, leaf × 1/2; H, leaf × 1/2; J, leaf ×
1/2. Anthurium friedrichsthalii: A, Lehmann s.n. (K); A. vallense: B, Nee & Hale 9628 (K); A. carnosum: C, Valerio 181 (K); A. melastomatis:
D, McPherson 7678 (K); A. smithii: E, Hahn & Grifo 3323 (K); A. antrophyoides: F, Lehmann 787 (K); A. peltigerum: G, Madison et al. 4599 (K);
A. clidemioides: H, Stevens 24526 (K) & Bown 131/37 (Kew slide collection); A. puberulinervium: J, Croat 55033 (K).
104
THE GENERA OF ARACEAE
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C
B
A
D
E
Plate 8 (ii). Anthurium. A, leaf × 1/2; B, leaf × 1/2; C, leaf × 1/2; D, leaf × 1/2; E, leaf × 1/2. Anthurium watermaliense: A, Croat 36713 (K);
A. rimbachii: B, Hepper 6445 (K); A. trisectum: C, Bogner 1088 (K); A. longissimum: D, Kalbreyer 853 (K); A. polyschistum: E, Paterson 121 (K).
P OT H O I D E A E : A N T H U R I U M
105
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A
B
C
D
Plate 8 (iii). Anthurium. A, habit × 1/16; B, habit × 1/8; C, habit × 1/2; D, habit × 1/2. Anthurium salviniae: A, Cult. Kew 1961–66404; A.
oerstedianum: B, Cult. Kew 1981–3725; A. interruptum: C, Davidse & Herrera 31343 (K); A. melastomatis: D, McPherson 7678 (K).
106
THE GENERA OF ARACEAE
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A
B
C
D
E
Plate 8 (iv). Anthurium. A, habit × 1/3; B, habit × 1/8; C, habit × 1/16; D, habit × 1/3; E, habit × 1/6. Anthurium radicans: A, Cult. Kew.
1977–5366; A. andraeanum: B, Cult. Kew 1963–49801; A. warocqueanum: C, Cult. Kew. 1986–6028; A. affine: D, Harley et al. 19429 (Kew
slide collection); A. wendlingeri: E, Cuadros et al. 3950 (K) & Nee et al. 8735 (K).
P OT H O I D E A E : A N T H U R I U M
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J
K
F
A
H
G
M
P
L
B
C
D
E
N
Plate 8 (v). Anthurium. A, inflorescence × 2; B, inflorescence, spathe mostly removed × 2; C, flower × 15; D, stamen, three quarter view ×
15; E, gynoecium, longitudinal section × 15; F, infructescence × 1; G, inflorescence, spathe mostly removed × 2; H, flower × 15; J, stamen ×
15; K, gynoecium, longitudinal section × 15; L, infructescence × 2; M, developing berry surrounded by persistent perigone × 8; N, inflorescence × 1; P, flower × 10. Anthurium globosum: A, Croat 67966 (K & Kew spirit collection 58085); A. regale: B–E, Cult. Kew 1962–67111 (Kew
spirit collection 51391); A. scandens subsp. scandens: F, Cult. Kew 1984–8010 (Kew spirit collection 52038); A. polyschistum: G–K, Cult. Kew
1976–1533 (Kew spirit collection 51386); A. sp.: L–M, (Kew spirit 59068); A. radicans: N–P, Cult. Kew. 1977–5366 & (Kew spirit collection 58028).
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THE GENERA OF ARACEAE
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ulate or subrugulate, rarely tuberculate, muri ± psilate or
spinulose, apertural exine mostly psilate, rarely spinulose.
GYNOECIUM: ovary ovoid to oblong or obovoid, 2-locular,
ovules 1–2 per locule, rarely more, anatropous, hemianatropous or subcampylotropous, funicle short, placenta axile
near apex of septum, stylar region inconspicuous to attenuated; stigma small, subcapitate, secreting conspicuous
nectar droplet at anthesis. BERRY: variously shaped from
globose to elongate-fusiform, when mature exserted from
tepals and usually held dangling by tiny strips of inner tepal
epidermis, sometimes simply falling out of spadix, 2–4seeded (more in sect. Tetraspermium), variously coloured, from
con-spicuous reds and oranges to dull purplish green, white
or blueish. SEED: ± oblong to ellipsoid or subglobose,
sometimes curved, testa usually smooth or somewhat verrucose, thin, usually with sticky gelatinous mass adhering
to raphe, small strophiole sometimes present, embryo axile,
subcylindric to conoid, sometimes curved, endosperm copious. See Plates 8i–v, 108C.
CHROMOSOMES: 2n = 30, 60, 90 (20, 24, 28, 40, 48, 56, 84)
DISTRIBUTION: over 800 spp.; tropical America, West
Indies:– Argentina, Belize, Bolivia, Brazil, Colombia, Costa
Rica, Cuba, Dominican Republic, Ecuador, El Salvador, French
Guiana, Guatemala, Guyana, Haiti, Honduras, Jamaica, Lesser
Antilles, Mexico, Nicaragua, Panama, Paraguay, Peru, Puerto
Rico, Surinam, Trinidad & Tobago, Uruguay, Venezuela.
ECOLOGY: tropical humid forest, especially diverse in cloud
forests; climbing hemiepiphytes, terrestrial on forest floor,
epiphytes, lithophytes, rarely helophytes or rheophytes.
NOTES: 19 sections are recognized by Croat & Sheffer
(1983):– Tetraspermium, Gymnopodium, Porphyrochitonium, Pachyneurium, Polyphyllium, Leptanthurium,
Oxycarpium, Xialophyllium, Polyneurium, Anthurium (syn.
Urospadix), Episeiostenium, Digitinervium, Cardiolonchium,
Chamaerepium, Calomystrium, Belolonchium, Semaeophyllium, Schizoplacium, Dactylophyllium.
ETYMOLOGY: Greek anthos (flower), oura (tail) and -ion
(diminutive).
TAXONOMIC ACCOUNTS: Engler (1905), Madison (1978c),
Croat (1980), Mayo (1982), Croat & Sheffer (1983), Croat (1984,
1986), Rodriguez (1987, 1989), Croat (1991), Sakuragui (1994).
C
IV. Subfamily Monsteroideae
Subfamily Monsteroideae Engler in Nova Acta Acad. Leopold.-Carol. 39: 142 (1876).
Laticifers absent; trichosclereids (H- or T- shaped) abundant
(except Anadendreae, Heteropsideae; in Amydrium present
only in certain parts); terrestrial, climbing hemiepiphytes or
more rarely epiphytes; petiole geniculate apically, sheath
usually long; leaf blade never sagittate, base narrowed to
subcordate, sometimes pinnatifid or perforated, outline
always ± oblong-ovate to -elliptic or narrower, often oblique;
spathe expanded or boat-shaped, not constricted centrally;
spadix fertile to apex; flowers bisexual, perigone present or
absent, 2-merous (2–3-merous in Spathiphylleae).
C
Tribe Spathiphylleae
Tribe Spathiphylleae Engler in Engler & Prantl, Nat.
Pflanzenfam. II (3): 112, 121 (1887).
Laticifers absent; tissues with small trichosclereids occurring
in bundles; leaves sometimes distichous, petiole sheath long;
blade oblong, cuspidate-acuminate, higher order venation
parallel-pinnate; inflorescence solitary; spathe persistent or
marcescent; flowers bisexual, perigoniate, 2–3-merous; tepals
free or connate, thecae dehiscing by longitudinal slit, pollen
inaperturate, exine striate; ovules anatropous to hemianatropous; seed ± oblong, narrowed towards micropyle,
endosperm copious.
C
9. Spathiphyllum
Spathiphyllum Schott in Schott & Endlicher, Melet. Bot. 22
(1832). TYPE: S. lanceifolium (Jacquin) Schott (“lancaefolium”; Dracontium lanceaefolium Jacquin)
SYNONYMS: Hydnostachyon Liebmann in Vidensk.
Meddel. Dansk Naturhist. Foren. Kjøbenhavn 1849: 23 (1849);
Massowia K. Koch in Bot. Zeitung (Berlin) 10: 277 (1852);
Spathiphyllopsis J.E. Teysmann & S. Binnendijk, Natuurk.
9. Spathiphyllum
MONSTEROIDEAE : SPATHIPHYLLUM
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26a Tribes & Genera Acro 17/7/97 16:45 Page 110
Tijdschr. Ned.-Indië 25: 400 (1863); Amomophyllum Engler in
Gard. Chron., ser. 2, 7: 139 (1877, non Watelet 1866);
[Massovia Bentham & J.D. Hooker, Gen. Pl. 3: 998 (1883),
orth. var.].
Trichosclereids present. HABIT: evergreen herbs usually
with short, erect to creeping stem, appearing acaulescent,
sometimes stoloniferous, occasionally erect and climbing
(S. solomonense). LEAVES: several. PETIOLE: geniculate apically, sheath long. BLADE: oblong to elliptic or narrowly
elliptic, cuspidate-acuminate; primary lateral veins pinnate,
running into marginal vein, secondary and tertiary laterals
parallel-pinnate, higher order venation transverse-reticulate.
INFLORESCENCE: solitary. PEDUNCLE: subequal to or
longer than petiole. SPATHE: oblong, elliptic, ovate or obovate, cuspidate-acuminate, ± decurrent at insertion,
membranaceous to subcoriaceous, fully expanded, rarely
fornicate or clasping, persistent, with distinct midrib and
pinnate primary lateral veins, usually white, rarely green,
turning green in fruit. SPADIX: usually stipitate, rarely sessile, stipe often partially adnate to spathe, spadix cylindric,
erect, shorter than spathe. FLOWERS: bisexual, perigoniate;
tepals 4–6, free, fornicate and almost truncate at apex, or
partly or completely connate into a truncate cup. STAMENS:
4–6, free, filaments short, oblong, flattened, connective slender, thecae oblong-ellipsoid to ovoid, dehiscing by
longitudinal slit. POLLEN: inaperturate, ellipsoid to ellipsoid-oblong, medium-sized (mean 32 µm., range 27–41 µm.),
exine striate. GYNOECIUM: ovoid, subcylindric, obovoid or
flask-shaped, ovary 3-locular, more rarely 2- or 4-locular,
ovules 2, 4, 6 or 8 per locule, anatropous to hemianatropous,
placenta axile, stylar region usually long, conic and longexserted beyond perigone, sometimes shortly attenuate,
sometimes ± truncate and not exserted and inconspicuous,
stigma 2–3-lobed or subcapitate to punctiform. BERRY:
rounded, ovoid to obovoid, or conically attenuate apically,
1–8-seeded, greenish. SEED: oblong, ellipsoid to ovoid or
slightly curved and ± reniform, pale yellow to brown, funicle short, testa sparsely foveolate, otherwise smooth or
verrucose, embryo axile, elongate, slightly curved,
endosperm copious. See Plates 9, 108D.
CHROMOSOMES: 2n = 30, 60.
DISTRIBUTION: 41 spp.; tropical America, West Indies, eastern Malay Archipelago, Melanesia:– Belize, Brazil (Amazonia,
Central-West, Northeast), Colombia, Costa Rica (incl. Isla del
Coco), Ecuador, El Salvador, French Guiana, Guatemala,
Guyana, Honduras, Indonesia (Irian Jaya, Moluccas, Palau Is.,
Sulawesi), Mexico, Nicaragua, Panama, Papua New Guinea
10. Holochlamys
(incl. New Britain, New Ireland), Peru, Philippines, Solomon
Is., Surinam, Trinidad, Venezuela.
ECOLOGY: tropical humid forest, rarely cloud forest; forest
floor, in wet sites, sometimes on rocks in streams, rarely
hemiepiphytic (S. solomonense).
NOTE: Bunting (1960a) recognized 4 sections:– sect.
Spathiphyllum, sect. Dysspathiphyllum, sect. Amomophyllum,
sect. Massowia; S. solomonense has recently been placed in
a separate section, sect. Chlaenophyllum (Nicolson 1994).
ETYMOLOGY: Greek spathe (spathe) and phyllon (leaf).
TAXONOMIC ACCOUNTS: Engler & Krause (1908), Bunting
(1960a), Nicolson (1968b, 1994), Williams & Dressler (1976).
10. Holochlamys
Holochlamys Engler in Beccari, Malesia 1: 265 (1883). TYPE:
H. beccarii (Engler) Engler (Spathiphyllum beccarii Engler).
Trichosclereids present. HABIT: evergreen herbs, stem
short, upright. LEAVES: several. PETIOLE: geniculate apically. BLADE: oblong-elliptic, or ovate to lanceolate, often
oblique, apex cuspidate to acuminate, base attenuate to
rounded; primary lateral veins pinnate, running into marginal vein, secondary and tertiary laterals parallel-pinnate,
higher order venation forming transverse cross connections, often obscured. INFLORESCENCE: solitary.
PEDUNCLE: shorter than petiole. SPATHE: white, with distinct midrib and pinnate primary lateral veins, tightly
clasping the spadix, marcescent after anthesis, gradually
decomposing. SPADIX: sessile to shortly stipitate, cylindric, fertile to apex. FLOWERS: bisexual, perigoniate; tepals
4, fornicate apically and ± truncate, connate into a truncate
cup. STAMENS: 4, free, filaments short, oblong, subequal
to anthers, connective slender, thecae oblong, dehiscing by
longitudinal slit. POLLEN: inaperturate, ellipsoid, mediumsized (mean 33 µm., range 32–34 µm.), exine striate.
GYNOECIUM: subcylindric to ovoid, ovary 1-locular, ovules
many, anatropous, funicle long, placenta basal, stylar
region cylindric, ± as broad as ovary, stigma oblong or
3–4-lobed. BERRY: 1–few-seeded. SEED: irregularly oblongellipsoid, narrowed towards micropyle, testa minutely
verrucose or smooth, embryo elongate, endosperm copious.
See Plate 10.
CHROMOSOMES: 2n = 60.
DISTRIBUTION: 1 sp.; Indonesia (Irian Jaya), Papua New
Guinea (incl. New Britain).
ECOLOGY: tropical humid forest; on forest floor, particularly along small streams, on river banks or on rocks.
ETYMOLOGY: Greek holos (whole) and chlamys (short mantle, cloak); refers to the connate tepals of the flowers.
TAXONOMIC ACCOUNTS: Engler & Krause (1908), Hay
(1990a).
Tribe Anadendreae
Tribe Anadendreae Bogner & French in Taxon 33(4): 689
(1984).
Laticifers and trichosclereids absent; climbing hemiepiphytes;
leaves distichous; petiole sheathed almost to apex; finer venation reticulate; peduncle relatively long; spathe boat-shaped
to reflexed, longer than spadix, marcescent or deciduous
soon after anthesis; flowers bisexual, perigone membrana-
110
THE GENERA OF ARACEAE
C
C
26a Tribes & Genera Acro 17/7/97 16:45 Page 111
A
Q
R
S
C
p
J
D
K
N
E
B
F
G
H
L
M
Plate 9. Spathiphyllum. A, habit × 1/5; B, leaf × 2/3; C, detail of leaf venation × 5; D, inflorescence × 2/3; E, detail of spadix × 3; F, flower
× 6; G, flower, perigone removed × 6; H, gynoecium, longitudinal section × 6; J, inflorescence × 2/3; K, detail of spadix × 3; L, flower with
developing fruit, longitudinal section × 6; M, fruit, transverse section × 6; N, inflorescence × 2/3; P, detail of spadix × 3; Q, flower × 6; R,
flower, perigone removed × 6; S, gynoecium, longitudinal section × 6. Spathiphyllum ‘Clevelandii’ : A, Cult Kew 1962–43301 (Kew slide collection); S. laeve: B–D, Dressler 4465 (K); S. cannifolium: E–H, Jermy 2872, Cult. Kew 1976–56863 (Kew spirit collection 37366); S. humboldtii:
J–K, Cremers 7813 (K); L–M, Jonker et al. 5845 (K); S. cochlearispathum: N–S, Cult. Kew 1972–68267 (Kew spirit collection 29047.83).
MONSTEROIDEAE : SPATHIPHYLLUM
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C
A
F
G
D
B
H
E
Plate 10. Holochlamys. A, habit × 1/6; B, leaf × 2/3; C, detail of leaf venation × 5; D, inflorescence, lower portion of peduncle removed ×
1; E, detail of spadix × 5; F, flower × 10; G, flower, perigone removed × 10; H, gynoecium, longitudinal section × 15. Holochlamys beccarii:
A–C, Cult. Kew 1970–1474; D, Sands 889 (Kew spirit collection 34304); E–H, Sands s.n. (Kew spirit collection 56122).
112
THE GENERA OF ARACEAE
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ceous, urceolate, shorter than gynoecium; stamens 4, thecae
dehiscing by longitudinal slit, pollen inaperturate; gynoecium truncate apically, ovary 1-locular, ovule 1,
hemianatropous, placenta basal, stigma transversely oblong
or subspheroid; embryo large, endosperm absent.
C
11. Anadendrum
Anadendrum Schott in Bonplandia 5: 45 (1857). LECTOTYPE:
A. montanum Schott (see Engler in De Candolle, Monogr.
Phan. 2: 97, 250 (1879)).
SYNONYMS: [Anadendron Schott in Oesterr. bot.
Wochenbl. 7: 118 (1857), orth. var.].
Trichosclereids absent. HABIT: climbing herbs. LEAVES: distichous. PETIOLE: geniculate apically, sheathed nearly to apex,
sheath persistent or marcescent. BLADE: obliquely ovateoblong, entire; primary lateral veins pinnate, running into
marginal vein, higher order venation reticulate. INFLORESCENCE: 1–3 in each floral sympodium. PEDUNCLE: relatively
long. SPATHE: oblong-ovate, boat-shaped to reflexed, greenish
white, rostrate apically and overtopping the spadix, deciduous
after anthesis. SPADIX: stipitate, cylindric. FLOWERS: bisexual,
perigoniate; perigone membranaceous, a single cup-like structure, truncate, equalling or shorter than gynoecium. STAMENS:
4, free, filaments relatively short, broad, spathulate, connective
slender, thecae linear-elliptic, dehiscing by longitudinal slit.
POLLEN: inaperturate, subspheroidal, small (mean 22 µm.),
exine psilate or subretipilate, pilae spinulose tipped and solitary, or united into groups of 2–4 or more. GYNOECIUM: ovary
obconic or obpyramidal, subquadrangular, 1-locular, ovule 1,
ana-tropous, funicle short, placenta basal, stylar region as broad
as ovary, stigma transversely oblong. BERRIES: distinctly truncate apically, subglobose, orange red (A. microstachyum).
SEED: rounded, subglobose, testa smooth, glossy, embryo
large, endosperm absent. See Plate 11.
CHROMOSOMES: 2n = 60.
DISTRIBUTION: ca. 7 spp.; southeast Asia, Malay Archipelago:Brunei, Cambodia, China (Guandong, Hainan, Yunnan),
Indonesia (Borneo, Java, Sulawesi, Sumatra), Laos, Malaysia
(Borneo, Peninsula), Philippines, Thailand, Vietnam.
ECOLOGY: tropical humid forest; climbing hemiepiphytes,
sometimes on rocks.
ETYMOLOGY: Greek ana (up) and dendron (tree), a tree
climber.
TAXONOMIC ACCOUNTS: Engler (1905), Bogner & French
(1984).
C
Tribe Heteropsideae
Tribe Heteropsideae Engler in Engler, Pflanzenreich 21
(IV.23B): 20 (1905).
Laticifers and trichosclereids absent; climbing hemiepiphytes,
main shoot monopodial, flowering articles usually short, axillary; leaves distichous; petiole usually almost entirely adnate to
succeeding internode, leaving only apical geniculum free; blade
oblong to lanceolate, primary and secondary lateral veins parallel-pinnate, forming submarginal collective vein, higher order
venation reticulate; spathe boat-shaped, marcescent or deciduous soon after anthesis; flowers bisexual, perigone absent;
stamens 4, thecae dehiscing by apical slit, pollen zonate or
dicolpate; gynoecium truncate, ovary incompletely 2-locular,
ovules 2 per locule, anatropous, placenta axile at base of partial septum, stigma oblong or rounded; endosperm absent.
C
12. Heteropsis
Heteropsis Kunth, Enum. Pl. 3: 59 (1841). LECTOTYPE: H.
salicifolia Kunth (see Nicolson in Taxon 24: 468. 1975).
Trichosclereids absent. HABIT: evergreen climbing herbs with
woody-fibrous roots. LEAVES: numerous. PETIOLE: usually
very short, entirely geniculate, concave and somewhat flat-
11. Anadendrum
MONSTEROIDEAE : HETEROPSIS
113
26a Tribes & Genera Acro 17/7/97 16:46 Page 114
B
C
E
A
F
G
D
Plate 11. Anadendrum. A, habit × 2/3, B, detail of leaf venation × 5; C, juvenile habit × 5; D, detail of spadix × 5; E, flower × 6; F, flower,
perigone removed × 6; G, gynoecium, longitudinal section × 6. Anadendrum microstachyum: A, Cult. Kew 1982–4984, Scortechini 82 (K);
B, de Wilde 14630 (K); C, ‘Native collector’ 2398 (K); D–F, Cult. Kew 1982–4984; G, Burkill 3231 (K).
114
THE GENERA OF ARACEAE
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E
F
B
G
H
A
C
J
D
L
K
Plate 12. Heteropsis. A, habit × 2/3; B, detail of leaf venation × 5; C, fruiting habit × 2/3; D, juvenile habit × 2/3; E, spadix × 2; F, detail
of spadix × 5; G, flower × 10; H, gynoecium, longitudinal section × 10; J, berry × 2; K, berry, longitudinal section × 2; L, berry, transverse
section × 2. Heteropsis spruceana: A–B, Traill 1135 (K); H. oblongifolia: C, E–L, Bell et al. 88–178 (K); Gentry & Young 31969 (K); Pinheiro
& Santos 2266 (K) & Santos 1276 (K); H. cf. jenmanii: D, Harley et al. 17848 (K).
MONSTEROIDEAE : HETEROPSIS
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ETYMOLOGY: Greek heteros (different) and opsis (appearance); this aroid is different from all others in that the petiole
sheaths are adnate to the internodes in most species, leaving
only a very short free portion of the petiole.
TAXONOMIC ACCOUNT: Engler (1905).
Tribe Monstereae
C
Tribe Monstereae Engler in Nova Acta Acad. Leopold.Carol. 39: 143 (1876).
12. Heteropsis
tened, sheath adnate to subtended internode, rarely petiole
free with long sheath (e.g. H. melinonii). BLADE: oblong, elliptic or lanceolate, ± long-cuspidate, subcoriaceous; primary
lateral veins pinnate, forming a submarginal collective vein
very close to margin, 1(-2) marginal veins also present, secondary laterals ± parallel to primaries, higher order venation
reticulate. INFLORESCENCE: solitary, subtended by several
small cataphylls, borne terminally on free, axillary branches.
PEDUNCLE: very short. SPATHE: ovate-elliptic to ovate-oblong,
cuspidate, convolute, opening at anthesis, then caducous.
SPADIX: erect, free, stipitate, shorter than spathe, cylindric or
ellipsoid. FLOWERS: bisexual, or lowermost flowers female by
abortion of stamens, perigone absent. STAMENS: 4 or fewer by
abortion, free, filaments short, flattened, rather broad, connective slender, thecae ovate-ellipsoid, overtopping connective a
little, dehiscing by apical slit. POLLEN: zonate or dicolpate,
ellipsoid-oblong or hamburger-shaped, medium-sized (mean 40
µm., range 37–42 µm.), exine foveolate or foveolate-fossulate,
apertural exine psilate. GYNOECIUM: obpyramidal- prismatic,
truncate, ovary incompletely 2-locular with conspicuous septal aperture, ovules 2 per locule, anatropous, collateral, placenta
axile at base of partial septum, stylar region dense and thickened, broader than ovary, stigma very small, ellipsoid, oblong
or subhemispheric. BERRY: shortly obovoid or obpyramidal, ±
prismatic, stylar region forming a ± broad, flattened scar-like
structure, 1-4 seeded, orange or greenish-white with brown
apex. SEED: obovoid to ellipsoid, testa thin, smooth, black,
shiny, embryo large, endosperm absent. See Plate 12.
CHROMOSOMES: 2n = 28.
DISTRIBUTION: ca. 13 spp.; tropical America:- Bolivia, Brazil
(Amazonia, Atlantic region), Colombia, Costa Rica, Ecuador,
French Guiana, Guyana, Nicaragua, Panama, Peru, Surinam,
Venezuela.
ECOLOGY: tropical moist and humid forest; climbing
hemiepiphytes, sometimes on rocks.
NOTES: Heteropsis melinonii differs from other species of
the genus in having free petiole sheaths, but agrees in ovary
structure (incompletely 2-locular ovary with 2 ovules per
locule), leaf venation and lack of trichosclereids.
116
THE GENERA OF ARACEAE
Laticifers absent; trichosclereids abundantly present (sparse
in Amydrium), large, solitary and scattered in tissues; climbing hemiepiphytes and epiphytes; leaves distichous; petiole
sheath usually long, almost equalling petiole (except
Amydrium, Alloschemone); blade normally oblique; peduncle relatively short (except Stenospermation), spathe usually
erect and boat-shaped (except Amydrium), marcescent or
deciduous soon after anthesis; spadix equalling or shorter
than spathe; flowers bisexual, perigone absent; stamens 4,
thecae dehiscing by longitudinal slit not reaching base, pollen
usually fully zonate, dicolpate; style well developed, rather
massive, usually prismatic with ± truncate apex, as wide or
wider than ovary, containing abundant trichosclereids, stigma
± hemispherical to linear, appearing sessile; stylar region of
berry deciduous at maturity.
13. Amydrium
Amydrium Schott in Ann. Mus. Bot. Lugduno-Batavum 1:
127 (1863). TYPE: A. humile Schott
SYNONYMS: Epipremnopsis Engler, Pflanzenreich 37
(IV.23B): 1–3 (1908).
Trichosclereids sparsely present in vegetative parts (petiole
and sheath only, Seubert 1996b), more abundant in style
(Carvell 1989). HABIT: evergreen herbs, often very robust,
stem climbing or prostrate, usually producing long flagelliform shoots with reduced cataphylls. LEAVES: many, often
remote from one another. PETIOLE: geniculate apically,
sheath usually less than half as long as petiole. BLADE: ovatecordate or pandurate-trilobed or pinnatifid to pinnatisect,
sometimes with ± numerous round to oval perforations near
midrib; primary lateral veins pinnate, running into marginal
vein, higher order venation reticulate. INFLORESCENCE:
1–several in each floral sympodium. PEDUNCLE: erect, subequal or half as long as petiole. SPATHE: conchiform to ovate,
apiculate, sometimes reflexed at anthesis and then deciduous.
SPADIX: sessile to long-stipitate, sometimes very short.
FLOWERS: bisexual, perigone absent. STAMENS: 4, free, filaments short, broadly linear, anthers equalling or shorter
than filaments, thecae ovoid, extrorse, dehiscing by longitudinal slit. POLLEN: fully zonate, hamburger-shaped,
medium-sized (mean 39 µm., range 38–41 µm.), exine either
densely and minutely punctate in one half and virtually psilate in other, or uniformly foveolate-fossulate, apertural exine
psilate or obscurely verrucate. GYNOECIUM: obpyramidal or
obconoid, tetragonal, ovary 1-locular, ovules 2, anatropous,
funicle short, placenta near base of deeply intrusive septum,
stylar region broader than ovary, slightly prominent centrally
below stigma, otherwise ± truncate, stigma small, hemispheric. BERRY: subglobose, truncate to domed at apex,
white (A. medium, A. humile) or orange-red (A. zippelianum)
C
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L
K
H
G
B
C
J
D
A
M
E
F
Plate 13. Amydrium. A, partial habit × 2/3; B, leaf × 1/2; C, tip of flagelliform shoot × 2/3; D, detail of spadix × 3; E, flower × 6; F, gynoecium, longitudinal section × 6; G, infructescence × 1; H, fruit, transverse section × 4; J, leaf × 1/2; K, detail of leaf venation × 5; L, seed, side
view × 2; M, leaf × 1/2. Amydrium medium: A, Synge 35 (K); B, Foxworthy 4605 (K); C, Boyce 463, Cult. Kew 1989–3217; D–F, Motley 778 (K);
G, Boyce 763 (Kew spirit collection 59090); H, Sam & Dewol s.n. (K); A. zippelianum: J–K, Ridley 26 (K); A. humile: L–M, de Wilde 13078 (K).
MONSTEROIDEAE : AMYDRIUM
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13. Amydrium
when ripe. SEED: subglobose to heart-shaped, testa smooth,
glossy, embryo curved and partly green, endosperm present
(E. Seubert 1993). See Plates 13, 109A.
CHROMOSOMES: 2n = 60
DISTRIBUTION: 4–6 spp.; tropical southeast Asia, Malay
Archipelago:– Brunei, Burma, China (Guandong, Guangxi,
Guizhou, Hainan, Hubei, Hunan, Sichuan, Yunnan),
Indonesia (Borneo, Irian Jaya, Java, Moluccas, Sulawesi,
Sumatra), Malaysia (Borneo, Peninsula), Papua New Guinea,
Philippines, Thailand, Vietnam.
ECOLOGY: tropical humid forest; climbing hemiepiphytes on
tree trunks or creeping on forest floor (A. humile).
ETYMOLOGY: Greek amydron (obscure, faint) and ion
(diminutive).
TAXONOMIC ACCOUNTS: Nicolson (1968c), Carvell (1989a).
C
14. Rhaphidophora
Rhaphidophora Hasskarl in Flora 25 (2) Beibl. 1: 11 (1842).
TYPE: R. lacera Hasskarl, nom. illeg. (Pothos pertusa
Roxburgh, R. pertusa (Roxburgh) Schott).
SYNONYMS: Afrorhaphidophora Engler in Engler &
Prantl, Nat. Pflanzenfam. Nachtr. 3: 31 (1906); [Raphidophora
Hasskarl, Cat. Hort. Bogor. 58 (1844), orth.var.].
Trichosclereids abundant. HABIT: evergreen, usually climbing herbs, more rarely repent, often extremely robust,
climbing branches often thick, producing anchor and
feeder roots, flagelliform shoots also produced, stem often
square in cross section. LEAVES: many, distichous, juvenile
shingle plants occur in some species. PETIOLE: geniculate
14. Rhaphidophora
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THE GENERA OF ARACEAE
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C
D
B
K
F
A
E
M
G
H
J
L
Plate 14. Rhaphidophora. A, habit × 1/2; B, leaf × 1/2; C, detail of leaf venation × 5; D, leaf × 1/2; E, leaf × 1/2; F, detail of spadix × 5;
G, flower × 8; H, gynoecium, longitudinal section × 8; J, gynoecium, transverse section × 8; K, flower × 8; L, gynoecium, longitudinal section × 8; M, seed, side view × 20. Rhaphidophora foraminifera: A, Boyce 235 (Kew slide collection); de Wilde 14592 (K); de Wilde & de
Wilde-Duyfjes 18154 (K). R. glauca: B–C, Henry 12728 (K); R. tenuis: D, Haviland & Hose 3605 (K); R. sylvestris: E, Mamit S 33623 (K); F–J,
Cult. Kew 1967–460 (Kew spirit collection 35951); R. africana: K–L, Bogner 100 (Kew spirit collection 32065); R. decursiva: M, J. Arn. Arb.
57(4): 185–201, pl. I, 12 (1976).
MONSTEROIDEAE : RHAPHIDOPHORA
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F
C
G
H
J
A
E
B
D
K
Plate 15. Epipremnum. A, infructescences and associated stem × 1/2; B, leaf × 1/2; C, juvenile habit × 1/2; D, seed, side view × 5; E, inflorescence and subtending leaf × 1/2; F, detail of leaf venation × 5; G, detail of spadix × 3; H, flower × 5; J, gynoecium, longitudinal section
× 5; K, gynoecium, transverse section × 5. Epipremnum pinnatum: A, Kostermans 18558 (K); B, Bloembergen 3827 (K); C, Powell & Chey
783 (K); D, J. Arn. Arb. 57(4): 185–201, pl. I, 3 (1976); E. nobile: E–K, Forman 289 (K & Kew spirit collection 6919).
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apically, sheath usually relatively long. BLADE: lanceolate
or oblong, ± oblique, entire, perforate or pinnatifid to pinnatisect, often very large, lobes often subfalcately
narrowed; primary lateral veins pinnate, running into marginal vein, often not differentiated from secondaries,
secondary laterals ± parallel-pinnate, higher order venation
reticulate. INFLORESCENCE: usually solitary, rarely more.
PEDUNCLE: relatively short. SPATHE: boat-shaped, deciduous. SPADIX: subcylindric, conic, clavate, often extremely
thick, sessile to stipitate, shorter than spathe. FLOWERS:
bisexual, perigone absent. STAMENS: 4, free, filaments
oblong-linear, anthers much shorter than filaments, connective slender, thecae ellipsoid, dehiscing by longitudinal
slit. POLLEN: dicolpate, extended monosulcate to perhaps
fully zonate, ellipsoid or hamburger-shaped, medium-sized
(mean 33 µm., range 24–55 µm.), exine foveolate, subreticulate, rugulate, fossulate, scabrate, retiscabrate,
verrucate, or psilate. GYNOECIUM: obconic-prismatic to
oblong, truncate, ovary 1- to partially 2-locular, ovules few
to many, anatropous, funicle long, placentae parietal to
basal, sometimes ± subaxile, partial septa variably intrusive,
stylar region well developed, usually broader than ovary,
usually truncate apically, rarely elongate-conic, stigma
broadly elliptic or oblong and then transverse or longitudinal, or punctate-prominent. BERRY: usually many-seeded,
stylar region deciduous at maturity, red or yellow. SEED:
oblong, testa thin, smooth, embryo axile, straight,
endosperm copious. See Plates 14, 109B.
CHROMOSOMES: 2n = 60, 120 (42, 54, 56).
DISTRIBUTION: ca. 120 spp.; tropical Africa, tropical southeast Asia, Malay Archipelago, Melanesia, Australasia,
Pacific:– Australia (Queensland), Bangladesh, Bhutan,
Brunei, Burma, Cambodia, Cameroon, Caroline Is., China
(Fujin, Guandong, Guangxi, Guizhou, Hainan, Sichuan,
Taiwan, Xizang, Yunnan), Equatorial Guinea (Bioko, Rio
Muni), Fiji, Gabon, Ghana, India, Indonesia (Borneo, Irian
Jaya, Java, Moluccas, Palau Is, Sulawesi, Sumatra), Ivory
Coast, Japan (Bonin Is., Ryukyu Is.), Laos, Liberia, Malaysia
(Borneo, Peninsula), Nepal, New Caledonia, Nigeria, Papua
New Guinea, Philippines, Samoa, Sierra Leone, Singapore,
Solomon Is., Sri Lanka, Thailand, Togo, Uganda, Vanuatu,
Vietnam.
ECOLOGY: subtropical and tropical humid or rain forest or
deciduous forest; climbing hemiepiphytes, rarely rheophytic
(R. beccarii).
ETYMOLOGY: Greek rhaphis, rhaphidos (needle) and pherô
(I bear); refers to the macroscopic (to 1cm long), needle-like
unicellular trichosclereids present in tissues.
TAXONOMIC ACCOUNTS: Engler & Krause (1908), Sivadasan
(1982), Nicolson (1988a), Hay (1990a, 1993b).
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15. Epipremnum
Epipremnum Schott in Bonplandia 5: 45 (1857). TYPE: E.
mirabile Schott (1858).
SYNONYM: Anthelia Schott in Ann. Mus. LugdunoBatavum 1: 127 (1863).
Trichosclereids abundant. HABIT: evergreen climbing herbs,
producing flagelliform shoots. LEAVES: several to many, distichous. PETIOLE: geniculate apically, sheath long,
marcescent to deciduous, often decomposing to conspicuous
net-fibrous mass. BLADE: entire, often oblique, lanceolate,
elliptic, elliptic- oblong, or pinnatipartite to pinnatisect, rarely
15. Epipremnum
minutely perforate (E. pinnatum); primary lateral veins pinnate, running into marginal vein, secondary and often
tertiaries parallel-pinnate, tertiary and higher order venation
often reticulate. INFLORESCENCE: 1(–2) in each floral sympodium. PEDUNCLE: relatively short. SPATHE: boat-shaped,
withering after anthesis, usually deciduous. SPADIX: subcylindric, conic, often quite thick, sessile or stipitate, shorter
than spathe. FLOWERS: bisexual, or lowermost ones female,
perigone absent. STAMENS: 4, free, filaments linear, somewhat broad, anthers much shorter than filaments, connective
slender, thecae oblong-ellipsoid, dehiscing by longitudinal
slit. POLLEN: fully zonate, hamburger-shaped, medium-sized
(mean 40 µm., range 36–44 µm.), exine foveolate-fossulate,
psilate at periphery, apertural exine coarsely verrucate.
GYNOECIUM: ovary subtetragonal-prismatic, truncate, 1-locular, ovules usually 2, more rarely 4 or 6–8 (E. amplissimum),
anatropous, funicle short, placenta parietal or near base of
parietal partial septa, stylar region prismatic, as broad or
broader than ovary, stigma umbonate to oblong-linear and
longitudinal. BERRY: 1–8-seeded, stylar region deciduous at
maturity. SEED: reniform, testa thickish, brittle, smooth,
embryo curved, endosperm copious. See Plates 15, 109C.
CHROMOSOMES: 2n = 60 (56, 84).
DISTRIBUTION: 20 spp.; tropical southeast Asia, Australasia,
Pacific:– Andaman Is., Australia (Queensland, Northern
Territories), Brunei, Burma, Cambodia, Caroline Is., China
(Guandong, Guangxi, Hainan, Taiwan,Yunnan), Fiji, Indonesia
(Irian Jaya, Java, Moluccas, Sulawesi, Sumatra, Timor), Japan
(Bonin Is., Ryukyu Is.), Malaysia (Borneo, Peninsula), Marshall
Is., Papua New Guinea, Philippines, Singapore, Solomon Is.,
Sri Lanka, Thailand, Vanuatu, Vietnam.
ECOLOGY: tropical humid forest; high-climbing hemiepiphytes, on trees and rocks.
NOTES: Engler & Krause (1908) kept Epipremnum separate
from Rhaphidophora because of the differences in seed
structure.
ETYMOLOGY: Greek prefix epi- (on) and premnon (bottom
of tree trunk).
TAXONOMIC ACCOUNTS: Engler & Krause (1908), Hay
(1990a).
MONSTEROIDEAE : EPIPREMNUM
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F
D
C
J
B
M
K
L
A
H
G
N
Plate 16. Scindapsus. A, habit × 1/3; B, stigma, top view × 6; C, juvenile habit × 1/3; D, habit × 1/3; E, detail of leaf venation × 5; F, seed,
side view × 2; G, habit showing fertile shoot and flagelliform shoot × 1/3; H, detail of spadix × 4; J, stigma, top view × 9; K, flower × 6;
L, gynoecium, longitudinal section × 6; M, stigma, top view × 6; N, flower with window cut in gynoecium to show ovule × 6. Scindapsus
rupestris: A, Chew & Corner 4253 (K); B, Beaman 9984 (K); S. pictus: C, Boyce 225 (K & Kew slide collection); S. officinalis: D–E, Kerr 20536
(K); F, J. Arn. Arb. 57(4): 185–201, pl. II, 31 (1976); S. beccarii: G, Boyce 318 (Kew slide collection); Cult. Kew 1965–47801 (Kew spirit collection 40953); H–L, Cult. Kew 1965–47801 (Kew spirit collection 40953); S. perakensis: M–N, Fedilis & Sumbing 68774 (K).
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16. Scindapsus
Scindapsus Schott in Schott & Endlicher, Melet. Bot. 21
(1832). LECTOTYPE: S. officinalis (Roxburgh) Schott (Pothos
officinalis Roxburgh; see Schott, Prodr. syst. Aroid. 395–397
(1860)).
Trichosclereids abundant. HABIT: evergreen climbing herbs,
sometimes very robust, sometimes producing flagelliform
shoots, shoots with leaves evenly spaced or forming rosulate
flowering zones separated by zones with elongated internodes
and smaller leaves, or solitary leaf trapping bole epiphyte.
LEAVES: many, juvenile plants often of shingle form. PETIOLE:
geniculate apically, sheath usually broad, rarely decomposing
to form persistent net-fibrous mass with abundant, stinging
sclereids. BLADE: always entire, lanceolate, elliptic or ovate to
obovate, acuminate, rarely variegated; primary lateral veins
hardly differentiated, pinnate, running into marginal vein, secondaries and also sometimes tertiaries parallel-pinnate, higher
order venation inconspicuous, transverse-reticulate. INFLORESCENCE: always solitary. PEDUNCLE: shorter than petiole.
SPATHE: boat-shaped, gaping only slightly, caducous to deciduous. SPADIX: sessile to shortly stipitate, cylindric, narrowly
ellipsoid or clavate, a little shorter than spathe. FLOWERS:
bisexual, perigone absent. STAMENS: 4, free, filaments oblong,
flattened, broadish, connective slender, thecae oblong-ellipsoid, dehiscing by apical slit. POLLEN: fully zonate,
hamburger-shaped, medium-sized (mean 38 µm., range 33–45
µm.), exine shallowly and sparsely punctate, scabrate or nearly
psilate. GYNOECIUM: ovary sometimes short, compressed ±
cylindric, 1-locular, ovules 1(–2), anatropous, funicle short,
placenta basal, stylar region well-developed, prismatic, truncate or with shortly conic central projection supporting stigma,
stigma globose, elongate-globose, elliptic, linear, or punctiform. BERRY: stylar region deciduous when mature, red. SEED:
rounded, subreniform, compressed, testa thickish, sparsely
verruculose or smooth, embryo curved, endosperm present
(Seubert 1993). See Plates 16, 109D.
CHROMOSOMES: 2n = 60 (42, 56, 58, 64, 70, 112).
DISTRIBUTION: ca. 36 spp.; tropical Asia, Malay Archipelago,
Melanesia, Pacific:– Andaman Is., Australia (Queensland),
16. Scindapsus
Bangladesh, Bhutan, Brunei, Burma, Cambodia, Caroline Is.,
China, Fiji, India (Assam, Bengal, Sikkim), Indonesia (Borneo,
Irian Jaya, Java, Moluccas, Sulawesi, Sumatra), Laos?, Malaysia
(Borneo, Peninsula), Nepal, Papua New Guinea, Philippines,
Samoa, Solomon Is., Sri Lanka, Thailand, Vietnam.
ECOLOGY: tropical humid forest or dry, deciduous or evergreen forest; climbing hemiepiphytes, also creeping over rocks,
often terrestrial when juvenile, rarely rheophytic (S. rupestris).
ETYMOLOGY: Greek skindapsos, once used for an ivy-like
plant.
TAXONOMIC ACCOUNTS: Engler & Krause (1908), Bogner
& Boyce (1994).
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17. Monstera
Monstera Adanson, Fam. Pl. 2: 470 (1763), nom. cons. TYPE:
M. adansonii Schott (Dracontium pertusum), typ. cons.
SYNONYMS: Tornelia Gutierrez ex Schott, Gen. Aroid. t.
74 (1858); Serangium W. Wood ex R.A. Salisbury, Gen. Pl.
Fragm. 5 (1866).
Trichosclereids abundant. HABIT: evergreen climbing herbs.
LEAVES: distichous, juvenile leaves sometimes of shingle plant
form, rarely variegated. PETIOLE: geniculate apically, sheath
usually long, persistent or decomposing to fibrous or membranous mass or entirely deciduous. BLADE: entire, oblique,
oblong to ovate-elliptic, often conspicuously and elaborately
perforated, more rarely deeply pinnatifid; primary lateral veins
pinnate, running into marginal vein, rarely forming an irregular submarginal collective vein (M. obliqua), secondary laterals
often parallel-pinnate, sometimes reticulated (e.g. M. dubia),
higher order venation reticulate. INFLORESCENCE: 1–several
in each floral sympodium. PEDUNCLE: shorter than petiole.
SPATHE: ovate or oblong-ovate, cuspidate, boat-shaped and
somewhat convolute basally, white to rose-coloured within,
remaining open after anthesis, caducous. SPADIX: sessile, subcylindric, somewhat shorter than spathe. FLOWERS: bisexual,
perigone absent, lowermost flowers usually sterile. STAMENS:
4, free, filaments flattened, connective slender, thecae oblongellipsoid, dehiscing by longitudinal slit. POLLEN: fully zonate,
17. Monstera
MONSTEROIDEAE : MONSTERA
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D
B
F
M
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A
N
P
J
K
L
H
Plate 17. Monstera. A, leaf × 1/3; B, detail of leaf venation × 5; C, leaf × 1/3; D, gynoecium × 4; E, gynoecium, longitudinal section × 4;
F, leaf × 1/3; G, infructescence × 1/3; H, inflorescence × 1/3; J, detail of spadix showing emerging stamens × 2; K, flower × 4; L, gynoecium,
longitudinal section × 4; M, seed, side view × 3; N, flowering shoot × 1/3; P, juvenile shingle habit × 1/3. Monstera oreophila: A–B, Grayum
et al. 6395 (K); M. subpinnata: C, Santos & Souza 1667 (K); D–E, Vasquez 1853 (K); M. adansonii var. laniata: F, Gomez 19565 (K); G,
Whitmore 749 (Kew spirit collection 25790); M. lechleriana: H–L, Cult. Mason (Kew spirit collection 29047.113); M, J. Arn. Arb. 57(4): 185–201,
pl. III, 40 (1976); M. tuberculata var. tuberculata: N, Mayo & Madison 341 (Kew spirit collection 29047.346) & Contr. Gray Herb. 207: 3–100,
f. 63 (1977); P, Mayo & Madison 341 (K).
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hamburger-shaped, medium-sized (mean 48 µm, range 40–52
µm), exine densely foveolate to subreticulate, sparsely and
shallowly foveolate or psilate, apertural exine verrucate or
rugulate. STERILE FLOWERS: with 4 minute, conic staminodia, pistillode 2-locular, prismatic, lacking ovules.
GYNOECIUM: obovoid to ellipsoid, prismatic, ovary 2-locular,
ovules 2 per locule, anatropous, funicle short, placenta axile
at base of septum; stylar region often massive, broader than
ovary, apex truncate to shortly attenuate, stigma oblong-elliptic to linear and longitudinal or round. BERRY: 1–3-seeded,
shedding prismatic stylar region at maturity, pulpy within.
SEED: obovoid to ellipsoid, compressed, testa smooth, embryo
large, endosperm absent. See Plates 17, 110A.
CHROMOSOMES: 2n = 60 (24, 48, 56, 58, 70).
DISTRIBUTION: ca. 40 spp. (T. Croat, pers. comm.); tropical
America, West Indies:– Belize, Bolivia, Brazil, Colombia,
Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala,
Guyana, Honduras, Lesser Antilles, Mexico, Nicaragua,
Panama, Peru, Surinam, Trinidad & Tobago, Venezuela.
ECOLOGY: tropical moist and humid forest, cloud forest;
climbing hemiepiphytes, usually on tree trunks, also on rocks
or ground (M. deliciosa).
NOTES: Madison (1977a) recognized four sections:– sect.
Monstera, sect. Marcgraviopsis, sect. Echinospadix and sect.
Tornelia.
ETYMOLOGY: Latin monstrum (monster), refers to the peculiar perforations of the leaves of many species.
TAXONOMIC ACCOUNTS: Engler & Krause (1908), Madison
(1977a).
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18. Alloschemone
Alloschemone Schott, Gen. Aroid. 99 (1858). TYPE: A.
poeppigiana Schott, nom. illeg. (Scindapsus occidentalis
Poeppig, A.. occidentalis (Poeppig) Engler & Krause).
Trichosclereids abundant. HABIT: evergreen climbing herbs,
stem epidermis becoming distinctly corky and longitudinally
furrowed with age. LEAVES: large, juvenile leaves entire,
ovate to ovate-elliptic. PETIOLE: geniculate apically, thickened at base, sheath short. BLADE: pinnatifid, subcordate,
lobes acute, falcate, 4–6 per side, primary lateral veins 1 per
lobe, secondary laterals ± parallel-pinnate, higher order venation reticulate. INFLORESCENCE: solitary. PEDUNCLE: shorter
than petiole. SPATHE: ovate-cymbiform, deciduous. SPADIX:
stipitate, cylindric, apex obtuse. FLOWERS: bisexual, perigone
absent. STAMENS: 4, free, filaments flattened, free or connate,
shorter than ovary, thecae oblong, dehiscing laterally by
oblique, apical, pore-like slit. POLLEN: not fully zonate, ellipsoid, medium-sized (mean 46 µm), exine shallowly foveolate.
GYNOECIUM: ovary prismatic, 1-locular, with abundant locular mucilage, ovule 1, amphitropous, funicle with trichomes,
placenta basal, stylar region densely packed with trichosclereids, stigma sessile, elliptic. BERRY: unknown. SEED:
unknown. See Plate 18.
CHROMOSOMES: 2n = 84.
DISTRIBUTION: 2 spp.; Brazil (Amazonas, Pará, Rondonia).
ECOLOGY: tropical humid forest; climbing hemiepiphytes.
NOTES: An incompletely known genus, which has been
attributed sometimes to Asiatic Scindapsus.
ETYMOLOGY: Greek allos (other), schema, schêmatos (form)
and ône (being).
TAXONOMIC ACCOUNTS: Engler & Krause (1908), Madison
(1976a), Boyce & Bogner (in prep.).
18. Alloschemone
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19. Rhodospatha
Rhodospatha Poeppig in Poeppig & Endlicher, Nov. Gen.
Sp. 3: 91 (1845). LECTOTYPE: R. latifolia Poeppig (see
Nicolson in Taxon 16: 518. 1967).
SYNONYMS: Anepsias Schott, Gen. Aroid. t. 73 (1858);
Atimeta Schott, Gen. Aroid. t. 71 (1858).
Trichosclereids abundant. HABIT: evergreen, usually climbing herbs, producing flagelliform shoots. LEAVES: many,
distichously arranged. PETIOLE: geniculate apically, sheath
long, persistent to marcescent. BLADE: oblong-elliptic, ±
oblique, always entire; primary lateral veins pinnate, numerous, running into ± distinct marginal vein, secondary and
tertiary laterals parallel-pinnate, higher order venation transverse-reticulate. INFLORESCENCE: usually solitary.
PEDUNCLE: shorter to longer than petiole. SPATHE: broadly
ovate or oblong-ovate, abruptly cuspidate, yellowish white,
cream, purplish or pink within, caducous after anthesis.
SPADIX: long-stipitate to sessile, cylindric-conic, basal flowers sometimes sterile or female and scattered. FLOWERS:
bisexual, perigone absent. STAMENS: 4, free, filaments linear-oblong, flattened, connective slender, thecae ovoid to
ellipsoid, dehiscing by longitudinal slit. POLLEN: extruded
in strands, fully zonate or inaperturate, hamburger-shaped or
ellipsoid to oblong, medium-sized (mean 47 µm., range
34–57 µm.), exine densely to sparsely foveolate and nearly
psilate to obscurely fossulate or verrucate. GYNOECIUM:
compressed obconic to cylindric, ovary 2-locular, ovules
usually numerous per locule, rarely few (R. venosa), anatropous to hemianatropous, funicle fairly long, placenta axile,
rarely subbasal, stylar region well-developed, broader than
ovary, prismatic, truncate to convex apically, stigma elliptic
to linear, usually longitudinal. BERRY: cylindric-prismatic,
MONSTEROIDEAE : RHODOSPATHA
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B
C
A
D
F
E
G
H
J
Plate 18. Alloschemone. A, leaf × 1/3; B, detail of leaf venation × 5; C, leaf × 1/3; D, detail of leaf venation × 5; E, mature main stem showing corky epidermis × 1; F, inflorescence, part of spathe removed, remainder flattened out × 1/2; G, detail of spadix × 1; H, flower × 5; J,
gynoecium, longitudinal section × 5. Alloschemone sp.: A–B, E, Madison et al. 6310 (K); A. occidentalis: C–D, F, H–J, Plowman et al. 12207
(NY); G, Krukoff 7162 (NY).
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F
K
D
H
B
J
E
C
A
G
L
Plate 19. Rhodospatha. A, habit × 1/2; B, flower × 8; C, gynoecium, longitudinal section × 8; D, seed × 20; E, habit × 1/2; F, detail of leaf venation × 5; G, detail of spadix × 5; H, flower × 8; J, gynoecium, longitudinal section × 8; K, gynoecium, transverse section × 16; L, flagelliform
shoot × 1. Rhodospatha oblongata: A–C, Harley et al. 18234 (K); D, Harley et al. 18193 (K); R. rubropunctata: E, J. Arn. Arb. 57(4): 185–201,
pl. I, 4 (1976); R. venosa: F–L, Montfort 155 (K).
MONSTEROIDEAE : RHODOSPATHA
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19. Rhodospatha
truncate, many- to few-seeded. SEEDS: rounded-reniform,
flattened, testa brittle, very hard, smooth or with verrucose
crest, embryo rather large, strongly curved, endosperm present but sparse. See Plates 19, 110B.
CHROMOSOMES: 2n = 28, 56.
DISTRIBUTION: ca. 75 spp. (T. Croat pers. comm.); tropical
America:– Belize, Bolivia, Brazil (Amazonia, Atlantic
region), Colombia, Costa Rica, Ecuador, French Guiana,
Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama,
Peru, Surinam, Trinidad, Venezuela.
ECOLOGY: tropical humid forest; climbing hemiepiphytes,
true epiphytes (?) or sometimes on rocks, juvenile plants
often on forest floor.
ETYMOLOGY: Greek rhodon (rose, roseate) and spathê
(spathe); refers to the spathe colour of some species.
TAXONOMIC ACCOUNTS: Engler & Krause (1908), Croat
(1978).
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20. Stenospermation
Stenospermation Schott, Gen. Aroid. t. 70 (1858). LECTOTYPE: S. mathewsii Schott (see Nicolson 1967).
SYNONYM: [Stenospermatium Schott in Oesterr. bot.
Zeitschr. 9: 39 (1859), orth. var.]
Trichosclereids abundant. HABIT: epiphytic, climbing
hemiepiphytic or terrestrial evergreen herbs, stem rather
densely leaved, erect, often elongated. LEAVES: many. PETIOLE: geniculate apically, sheath long. BLADE:
oblong-elliptic or lanceolate, oblique, often rather thick,
venation usually obscured; midrib narrowly sulcate above,
primary lateral veins weakly or not differentiated, pinnate,
128
THE GENERA OF ARACEAE
20. Stenospermation
running into margin, secondary laterals parallel-pinnate,
higher order venation inconspicuous. INFLORESCENCE:
solitary, often nodding. PEDUNCLE: relatively long. SPATHE:
convolute, gaping at anthesis, boat-shaped or opening
widely, white, caducous. SPADIX: usually stipitate, rarely
sessile, cylindric. FLOWERS: bisexual, perigone absent. STAMENS: 4, free, filaments oblong, flattened, connective
slender, thecae ovoid-ellipsoid, dehiscing by longitudinal
slit. POLLEN: extruded in strands, fully zonate or inaperturate, hamburger-shaped or subspheroidal, medium-sized
(mean 42 µm., range 30–58 µm.), exine psilate to shallowly
and sparsely foveolate, fossulate-foveolate, verrucate or
baculate. GYNOECIUM: compressed obconic to cylindric,
ovary (1–)2-locular, ovules 4–many per locule, anatropous,
arranged in 2 rows, funicles long, placenta basal, stylar
region well-developed, usually broader than ovary and truncate, stigma elliptic to punctiform. BERRY: obovoid, truncate
apically, locules 3–many-seeded, white, orange (S. ulei) to
reddish orange, or yellow. SEED: clavate to ellipsoid, raphe
prominent, testa thickish, smooth, embryo axile, elongate,
endosperm copious. See Plates 20, 110C.
CHROMOSOMES: 2n = 28.
DISTRIBUTION: ca. 36 spp.; tropical America:– Bolivia, Brazil
(Amazonia, Atlantic region), Colombia, Costa Rica, Ecuador,
French Guiana, Guatemala, Guyana, Nicaragua, Panama,
Peru, Surinam, Venezuela.
ECOLOGY: tropical humid forest, especially cloud forests;
epiphytes or terrestrial on forest floor.
NOTES: Vestigial tepals occasionally present (S. ulei).
ETYMOLOGY: Greek stenos (narrow), sperma, spermatos
(seed) and -ion (diminutive); refers to the slender seeds.
TAXONOMIC ACCOUNT: Engler & Krause (1908), Pérez de
Gómez (1983).
26b Tribes & Genera Acro 17/7/97 17:08 Page 129
E
F
D
G
H
B
C
A
K
J
Plate 20. Stenospermation. A, habit, inflorescence removed × 1/2; B, inflorescence × 1/2; C, gynoecium, longitudinal section; D, habit ×
1/2; E, detail of leaf venation × 5; F, detail of spadix × 5; G, flower × 10; H, gynoecium, longitudinal section × 10; J, infructescence × 1; K,
habit × 1/2. Stenospermation rusbyi: A–B, Rusby 2609 (K); S. ulei: C, E–H, Cult. Kew 1990–2738; D, Ule 8490 (K); S. angustifolium: J–K, Gómez
et al. 20533 (K).
MONSTEROIDEAE : STENOSPERMATION
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V. Subfamily Lasioideae
Subfamily Lasioideae Engler in Nova Acta Acad. Leopold.Carol. 39: 144 (1876); Hay (1992).
Laticifers and trichosclereids absent; terrestrial or rooted
aquatics, stem tuberous or rhizomatous, usually geophytic
(except Lasia, Podolasia); petiole usually aculeate or warty
or with striking coloration, long, usually ± geniculate apically;
primary lateral veins of leaf blade divisions pinnate to arcuate-parallel, higher order venation reticulate; spadix flowering
and fruiting in basipetal sequence; flowers bisexual, perigoniate (except Pycnospatha); tepals fornicate, ± truncate, free,
in 2 or more whorls, stamens free (except Lasimorpha) with
distinct filaments, anthers terminal, connective slender, pollen
monosulcate; stigma capitate to subcapitate; embryo large,
endosperm present (except Anaphyllum) and forming a thin
but distinct layer.
C
21. Dracontium
Dracontium L., Sp. Pl. 967 (1753). LECTOTYPE: D. polyphyllum L. (Britton & Wilson 1923, p.130).
SYNONYMS: Eutereia Rafinesque, Fl. Tell. 4: 12 (1838,
“1836”); Echidnium Schott in Oesterr. bot. Wochenbl. 7: 62
(1857); Ophione Schott in Oesterr. bot. Wochenbl. 7: 101
(1857); Chersydrium Schott in Oesterr. bot. Zeitschr. 15: 72
(1865); Godwinia Seemann in J. Bot. 7: 314 (1869).
HABIT: usually seasonally dormant, often robust, sometimes
gigantic herbs, tuber hypogeal, depressed-subglobose, often
bearing few to very numerous tubercles usually on upper
surface. LEAVES: usually solitary. PETIOLE: long, often verrucose-asperate, sometimes bearing few to many longer,
prickle-like processes, covered with striking, transversely
banded variegation, usually weakly geniculate at apex,
sheathed only at very base. BLADE: dracontioid, i.e trisect,
sometimes perforate, primary anterior division usually trisect at middle and primary posterior divisions bisect below
the middle, secondary and tertiary divisions further subdivided, ultimate lobes usually elliptic-acuminate, rarely linear
(D. margaretae); primary lateral veins of ultimate lobes pinnate, forming arching submarginal collective veins, higher
order venation reticulate. INFLORESCENCE: 1(–2), preceded
by cataphylls, appearing before, with or after the leaf.
PEDUNCLE: very short to long, epidermis similar to petiole.
SPATHE: oblong, usually ± boat-shaped, erect, acute, cuspidate to acuminate, often fornicate, convolute basally, gaping
above, sometimes pubescent within, marcescent to persistent,
usually dark brown-purple outside, more reddish-purple
within and often white at the base within. SPADIX: sessile to
stipitate, shortly cylindric to ellipsoid, much shorter than
spathe, apical flowers sometimes sterile or with enlarged,
irregularly shaped, projecting structures. FLOWERS: bisexual,
perigoniate; tepals 4–8, dilated apically, fornicate. STAMENS:
usually 4–6, free, sometimes up to 19, usually longer than
tepals at anthesis, filaments somewhat dilated, ± compressed,
anthers longer than connective, connective slender, thecae
oblong-ellipsoid, dehiscing by apical slit. POLLEN: extruded
in a conglutinate mass, monosulcate, ellipsoid to oblong,
medium-sized (mean 38 µm., range 29–48 µm.), exine foveolate-fossulate to subreticulate, apertural exine rugulate or
verruculate. GYNOECIUM: ovary ovoid, incompletely 1–6locular, ovules 1 per locule, anatropous or
130
THE GENERA OF ARACEAE
21. Dracontium
subcampylotropous, funicle short, placenta axile to subbasal,
stylar region as long or much longer than ovary, projecting
beyond perigone, stigma small, subcapitate or slightly 3—
lobed. BERRY: usually obpyramidal, bearing style rudiment,
greenish to brown. SEED: rounded-reniform, a little compressed, testa verrucose to almost smooth, rather thick,
embryo curved, endosperm present. See Plates 21, 110D.
CHROMOSOMES: 2n = 26
DISTRIBUTION: 23 spp.: tropical America, West Indies:–
Bolivia, Brazil (Amazonia, Central West), Colombia, Costa Rica,
Ecuador, French Guiana, Guyana, Mexico, Nicaragua, Panama,
Paraguay, Peru, Puerto Rico, Surinam, Trinidad, Venezuela.
ECOLOGY: tropical moist and humid forest, rarely in savannas (D. margaretae); geophytes on forest floor.
NOTES: Engler (1911) recognized 2 sections:– Sect. Dracontium, Sect. Godwinia; Sect. Echidnium is recognized by
modern workers (G.H. Zhu pers. comm.).
ETYMOLOGY: ancient name, Latin draco, dracontis (dragon,
snake) and suffix -ium (diminutive), referring to the similarities of the petiole markings to a snake; also perhaps from the
Greek drakontion.
TAXONOMIC ACCOUNTS: Engler (1911), Bogner (1986a),
Bunting (1986), Hay (1992a), Zhu (1996, 1997).
22. Dracontioides
Dracontioides Engler in Pflanzenreich 48 (IV.23C): 36
(1911). TYPE: D. desciscens (Schott) Engler (Urospatha
desciscens Schott).
SYNONYM: Dracontium sect. Urospathopsis Engler in
Bot. Jahrb. 5: 178 (1884).
HABIT: unarmed herbs, sometimes robust (to 2m), rhizome
subterranean, erect, sparsely branched, sometimes bearing a
few subterranean tubercles. LEAVES: several, ± erect. PETIOLE:
C
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H
K
B
C
J
P
R
F
D
T
A
Q
G
W
M
L
N
S
U
E
V
Plate 21. Dracontium. A, habit × 1/10; B, detail of petiole × 2/4; C, rachis/petiole insertion × 2/3; D, tubercules at soil–level junction of
petiole and tuber × 2/3; E, leaf segment × 1/2; F, leaf segment × 1/2; G, seedling × 1; H, partially buried inflorescence × 2/3; J, flower, longitudinal section × 6; K, inflorescence × 1/5; L, inflorescence × 2/3; M, spadix × 1; N, detail of spadix × 3; P, flower, longitudinal section ×
6; Q, spadix × 1; R, flower, longitudinal section × 6; S, leaf segment × 1/2; T, leaflet, transverse section × 1; U, infructescence × 1; V, berry,
side view × 3; W, seed, side view × 4. Dracontium asperum: A–D, Cult. Kew 1977–5355; D. gigas: E, Cult. Bull 1878 (K) & Cult. Bull 1881
(K); D. spruceanum: F, Plowman 4490 (K); G, Plowman 4490 (Kew illustration collection); D. changuango: H, Boyce s.n.; J, Aristeguieta
12734 (Kew spirit collection 53986); D. prancei : K, Cult. Kew 1977–5372 (Kew slide collection); D. asperum: L, Cult. Kew 1979–3887 (Kew
spirit collection 46575); M–P, Cult. Kew 1979–3887 (Kew spirit collection 29047.455); D. soconuscum: Q–R, Cult. Kew 1980–1628 (Kew spirit
collection 51365); D. margaretae: S, Emmerich 4053 (K illustration collection); T–W, Emmerich 4053 (Kew spirit collection 29047.358 & 43972).
LASIOIDEAE : DRACONTIUM
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F
G
K
L
H
J
D
C
E
A
B
Plate 22. Dracontioides. A, habit × 1/8; B, seedling × 1/3; C, perforate leaf × 2/3; D, eperforate leaf × 2/3; E, base of plant showing
erect rhizome and leaf–axillary tubercles × 2/3; F, inflorescence × 2/3; G, inflorescence, nearside half of spathe removed × 1; H, detail of
spadix × 5; J, flower, longitudinal section × 8; K, infructescence × 2/3; L, seed, side view × 3. Dracontioides desciscens: A, Harley et al.
18009 (Kew slide collection); B, Cult. Kew 1977–640 (Kew spirit collection 39121); C, Harley et al. 18009 (K); D, Lewis & de Carvalho 1060
(K); E, Harley et al. 18241A (Kew spirit collection 47695) & Lewis & de Carvalho 1060 (K); F–L, Harley et al. 18009 (Kew spirit collection
46561, 46564 & 47699).
132
THE GENERA OF ARACEAE
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23. Anaphyllopsis
Anaphyllopsis A. Hay in Aroideana 11 (1): 25–31 (1989,
“1988”). TYPE: A. americana (Engler) A. Hay
22. Dracontioides
long, smooth to roughened-verruculate, often transversely variegated, geniculate at apex, sheath less than half petiole length.
BLADE: deeply sagittate to subtripartite, often with a few perforations of irregular size between primary lateral veins; basal
ribs very well-developed, primary lateral veins mostly arising
near petiole insertion, very long-arcuate towards apex of each
division, running into margin, higher order venation reticulate.
INFLORESCENCE: solitary, appearing with leaves. PEDUNCLE: shorter than petiole. SPATHE: marcescent, tube with
convolute margins, longitudinally white-striped, blade strongly
fornicate, usually obscuring mouth of tube, brown-purple.
SPADIX: sessile to shortly stipitate, cylindric, obtuse, shorter
than spathe tube, flowering sequence basipetal. FLOWERS:
bisexual, perigoniate; tepals 4, fornicate, subtruncate. STAMENS: 4, free, strongly exserted from flower at anthesis,
anthers longer than connective, connective slender, thecae
ovate-ellipsoid, dehiscing by pore-like apical slit. POLLEN:
monosulcate, ellipsoid-oblong, small (mean 23 µm.), exine
subreticulate. GYNOECIUM: ovate-conoid, ovary 2-locular,
ovules 1 per locule, anatropous, placenta axile, stylar region
attenuate, longer than tepals, stigma small, button-like. BERRY:
obovoid, somewhat furrowed, 1–2-seeded, dark purplish-red.
SEED: reniform, attenuate towards micropyle, testa strongly
dentate-cristate, thick, hard, brown, embryo curved,
endosperm present. See Plates 22, 111A.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 1 sp.; Brazil (Atlantic region); the record
from Tijuca, Rio de Janeiro (Peyritsch 1879) is almost certainly
a mistake.
ECOLOGY: tropical humid forest; helophytes in swamp forest, marshes, stream margins, open or shaded sites, in peat
or sand.
ETYMOLOGY: Dracontium and Greek suffix -oides (resemblance), i.e. similar to Dracontium.
TAXONOMIC ACCOUNTS: Mayo (1978), Hay (1992a).
HABIT: seasonally dormant (A. americana), solitary herbs,
rhizome hypogeal, erect. LEAVES: solitary, rarely 2. PETIOLE: unarmed, smooth to tubercular, geniculate apically.
BLADE: pinnatifid and perforate or pinnatisect, juvenile
leaves entire; basal ribs well-developed, primary lateral veins
of ultimate lobes pinnate, higher order venation reticulate.
INFLORESCENCE: solitary, rarely 2. PEDUNCLE: long, similar to petiole in colour and texture. SPATHE: membranaceous,
convolute basally, spirally twisted apically, marcescent,
papery when dry. SPADIX: stipitate, stipe mostly adnate to
spathe, flowering sequence basipetal. FLOWERS: bisexual,
perigoniate; tepals 4, fornicate. STAMENS: 4, free, filaments
short, linear, connective slender, thecae dehiscing by short,
apical pore-like slit. POLLEN: monosulcate, ellipsoid,
medium-sized (31 µm.), exine foveolate, apertural exine psilate. GYNOECIUM: ovary 1–locular, ovules 1–2, anatropous,
placenta basal, stylar region ± attenuate, stigma subcapitate.
BERRY: ovoid to obpyramidal, reddish. SEED: campylotropous, testa thick, verruculose to channelled, embryo
curved, endosperm present. See Plates 23, 111B.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 3 spp., tropical South America:– Brazil
(Amazonia), French Guiana, Surinam, Venezuela.
ECOLOGY: tropical humid swamp forest; helophytes in
sandy, partially flooded places along streams, swamp forest.
ETYMOLOGY: Anaphyllum and Greek opsis (appearance);
i.e. “like Anaphyllum”.
TAXONOMIC ACCOUNTS: Hay (1989, 1992a).
23. Anaphyllopsis
LASIOIDEAE : ANAPHYLLOPSIS
133
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B
F
E
D
A
C
K
H
L
J
G
Plate 23. Anaphyllopsis. A, leaf × 1/4; B, gynoecium, longitudinal section × 5; C, leaf × 1/4; D, infructescence × 2/3; E, immature fruit,
longitudinal section × 6; F, seed, side view × 4; G, leaf × 1/4; H, base of plant showing erect rhizome × 1/2; J, inflorescence, nearside half
of spathe removed × 2/3; K, detail of spadix × 4; L, flower, nearside tepal removed × 6. Anaphyllopsis pinnata: A–B, Wessels Boer 2387 (U);
A. cururuana: C–F, Anderson 10627 (NY); A. americana: G, J, Leprieur 152 (P); H, Aroideana 11(1) 30, fig. 3 (1988) (as A. cururuana);
K–L, Mélinon 52 (P).
134
THE GENERA OF ARACEAE
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24. Pycnospatha
C
25. Anaphyllum
Pycnospatha Thorel ex Gagnepain in Bull. Soc. Bot. France
88: 511 (1941). TYPE: P. palmata Thorel ex Gagnepain
Anaphyllum Schott in Bonplandia 5: 126 (1857). TYPE: A.
wightii Schott
HABIT: seasonally dormant herbs with subglobose tuber.
LEAVES: 1–2. PETIOLE: smooth, rough or aculeate, mottled,
sheath very short, inconspicuous. BLADE: dracontioid, i.e.
trisect, anterior division trifid, segments simple to pinnatifid,
posterior divisions bifid to pedatifid, segments then simple to
pinnatifid, ultimate lobes decurrent, ovate-elliptic to triangular, acute to acuminate; primary lateral veins pinnate, running
into distinct marginal vein, higher order venation reticulate.
INFLORESCENCE: solitary, appearing before or with leaf.
PEDUNCLE: much shorter than petiole, similar in appearance
and texture to petiole. SPATHE: margins not overlapping,
strongly fornicate, thick, ± purple, marcescent. SPADIX: much
shorter than spathe, conic to ovoid-conoid, stipitate, fertile to
apex, flowering sequence basipetal. FLOWERS: bisexual,
perigone absent. STAMENS: ca. 6 or more per flower, free,
crowded densely together with those of neighbouring flowers, filaments oblong, flattened, connective slender, thecae
oblong-ellipsoid, dehiscing by apical, pore-like slit. POLLEN:
monosulcate, ellipsoid to oblong, medium-sized (mean 34
µm.), exine subreticulate to rugulate. GYNOECIUM: elongated-flask-shaped, ovary 1-locular, ovule 1, anatropous to
hemianatropous, funicle short, placenta basal to subparietal,
stylar region greatly elongated, straight or somewhat curved,
projecting well beyond stamens, stigma small, scarcely or no
broader than style. BERRY: globose, pericarp densely covered
with conic prickles, with conspicuous, persistent style remnant, dark green. SEED: reniform, black or very dark brown,
testa hard, thick, verrucose, containing white druses, embryo
large, ellipsoid to slightly curved, endosperm very sparse,
only a few cell layers thick. See Plates 24, 111C.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 2 spp.; tropical southeast Asia:– Laos,
Thailand, Vietnam.
ECOLOGY: tropical humid forest; geophytes on forest floor
in sandy loam.
ETYMOLOGY: Greek pyknos (compact, thick) and spathê
(spathe).
TAXONOMIC ACCOUNTS: Bogner (1973c), Hay (1992a),
Boyce (1993b).
HABIT: evergreen herbs, clump- or colony-forming, rhizome creeping. LEAVES: solitary to few. PETIOLE: smooth
to tuberculate, geniculate apically, sheath short. BLADE:
sagittate-hastate to pedatifid when juvenile, trisect at maturity, anterior division remotely pinnatisect with ±
oblong-lanceolate, acute lobes, the upper ones decurrent,
posterior divisions either ± oblong-lanceolate or deeply
divided into 3 coherent segments, rachis geniculate at insertion of anterior and posterior divisions; basal ribs
well-developed, primary lateral veins of ultimate lobes pinnate, running into marginal vein, higher order venation
reticulate. INFLORESCENCE: solitary. PEDUNCLE: very long
and slender, similar in colour and texture to petiole. SPATHE:
membranous to coriaceous, marcescent, either convolute
basally and becoming spirally twisted and long-acuminate
apically, or oblong-ovate, ± flat and fully expanded. SPADIX:
cylindric, much shorter than spathe, stipitate or sessile, flowering sequence basipetal. FLOWERS: bisexual, perigoniate,
tepals 3–4, fornicate. STAMENS: 3–5, free, filaments fairly
wide, connective slender, thecae ellipsoid, dehiscing by
short, apical, pore-like slit. POLLEN: monosulcate, ellipsoid,
medium-sized (mean 29 µm., range 25–33 µm.), exine foveolate to reticulate, sometimes with elevated psilate regions,
apertural exine psilate. GYNOECIUM: ovary ovoid, 1-locular, ovule 1, hemianatropous, funicle short, placenta parietal
on single intrusive septum, stylar region thick, attenuate,
stigma subcapitate, exuding droplet at anthesis. BERRY:
ovoid, smooth, red. SEED: ovoid, funicle slender, testa membranaceous, smooth, embryo stout, straight, endosperm
absent. See Plates 25, 111D.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 2 spp.; southern India (Kerala, Tamil Nadu).
ECOLOGY: tropical evergreen forest in leaf litter and in
swamp forest undergrowth; geophytes, rare.
ETYMOLOGY: Greek ana- (up, erect) and phyllon (leaf).
TAXONOMIC ACCOUNTS: Engler (1911), Sivadasan (1982),
Hay (1992a).
24. Pycnospatha
25. Anaphyllum
LASIOIDEAE : ANAPHYLLUM
135
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A
C
B
Q
P
D
F
H
G
L
N
M
E
J
K
Plate 24. Pycnospatha. A–E, leaf developmental sequence from first leaf (A) to flowering size (E) × 1/3; F, detail of petiole × 1; G, habit
× 1/8; H, inflorescence × 2/3; J, spathe sectioned to show spadix × 1; K, detail of spadix × 3; L, flower × 6; M, gynoecium, longitudinal section × 6; N, gynoecium, transverse section × 6; P, infructescence × 2/3; Q, seed, side view × 5. Pycnospatha arietina: A–F, Bogner 395 (K);
G, Cult. Kew 1971–1039 (Kew slide collection 8021); H–J, Bogner 395 (Kew spirit collection 34429); K–Q, Bogner 395 (Kew spirit collection
29047.184).
136
THE GENERA OF ARACEAE
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H
A
G
J
D
B
E
C
F
Plate 25. Anaphyllum. A, habit × 1/8; B, leaf × 1/3; C, base of plant × 2/3; D, inflorescence × 2/3; E, detail of spadix × 5; F, flower, longitudinal section × 6; G, seed, hilum view × 3; H, leaf × 1/3; J, inflorescence × 2/3. Anaphyllum wightii: A–B, Cult. Kew 1984–04519; Fliegner
245 (Kew spirit collection 49762 & 51853); C, Sivadasan CU 9060 (K); D–F, Cult. Kew 1983–02560; Hay s.n. (Kew spirit collection 49796);
G, Cult. Kew 1984–04519; Fliegner 245 (Kew spirit collection 51853); A. beddomei: H, Anon. s.n. (K); J, Blasco s.n. (K).
LASIOIDEAE : ANAPHYLLUM
137
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C
26. Cyrtosperma
Cyrtosperma Griffith, Notul. Pl. Asiat. (Posthum. Pap.) 3:
149 (1851); Icon. pl. Asiat. 3, t.169 (1851). TYPE: C. lasioides
Griffith (“lacioides”), [= C. merkusii (Hassk.) Schott].
SYNONYM: Arisacontis Schott in Bonplandia 5: 129 (1857).
HABIT: slender to gigantic evergreen herbs, usually solitary,
sometimes clump-forming, rhizome thick, condensed, creeping. LEAVES: several. PETIOLE: sometimes very long, aculeate,
geniculate apically, sheath short. BLADE: deeply sagittate,
hastate-sagittate or ± tripartite (posterior divisions usually
larger than anterior), veins sometimes aculeate on lower surface; basal ribs very well-developed, primary lateral veins
pinnate, running into marginal vein, higher order venation
reticulate. INFLORESCENCE: 1–2 in each floral sympodium,
appearing with the leaves. PEDUNCLE: long, similar to petioles. SPATHE: marcescent, erect, blackish purple to white,
convolute or not in lower part, upper part rarely somewhat
fornicate, long-acuminate and twisted in some species.
SPADIX: sessile or stipitate. FLOWERS: bisexual, perigoniate;
tepals 4–6, somewhat thickened at apex, fornicate. STAMENS:
4–6, free, filaments free, flat and broad, connective slender,
thecae oblong-ovate, dehiscing by apical slit. POLLEN: monosulcate, ellipsoid, medium-sized (mean 29 µm., range 28–30
µm.), exine foveolate, apertural exine psilate. GYNOECIUM:
1-locular, ovules 1–many, campylotropous to subamphitropous, placenta basal to parietal, stylar region short or
inconspicuous, stigma subhemispheric, exuding droplet at
anthesis. BERRY: obovoid, 1–7-seeded, usually red when
mature, bearing remnant of stigma (in C. cuspidispathum ripe
berries are extruded and dangle on strips of tepal epidermis;
A. Hay pers. comm.). SEED: reniform to orbicular to helically
twisted, cristate, warty or smooth, embryo curved, endosperm
present. See Plates 26, 112A.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 11–12 spp.; tropical southeast Asia, Malay
Archipelago, Melanesia, Pacific:– Brunei, Caroline Is., China
(cultivated?), Cook Is., Fiji, Gilbert & Ellice Is., Guam, Indonesia
26. Cyrtosperma
138
THE GENERA OF ARACEAE
(Borneo, Irian Jaya, Java, Palau Is., Sumatra), Malaysia (Borneo,
Peninsula), Mariana Is., Marquesas Is., Marshall Is., Papua New
Guinea, Philippines, Samoa, Singapore, Society Is., Solomon
Is., Tahiti, Vanuatu, Vietnam (cultivated?).
ECOLOGY: tropical humid forest, swamp forest, open
swamps and cultivated areas; helophytes in streams, ponds
and other wet places.
NOTES: Hay (1988) recognized 4 informal groups:– “Merkusii” group, “Cuspidispathum” group, “Carrii” group,
“Macrotum” group.
ETYMOLOGY: Greek kyrtos (curved) and sperma (seed); the
seeds are strongly curved.
TAXONOMIC ACCOUNTS: Engler (1911), Thompson (1982),
Hay (1988, 1992a).
27. Lasimorpha
Lasimorpha Schott in Bonplandia 5: 127 (1857). TYPE: L.
senegalensis Schott (syn. Cyrtosperma senegalense (Schott)
Engler).
SYNONYM: [Lasiomorpha Engler in Engler, Pflanzenreich 48 (IV.23C): 14 (1911), orth. var.].
HABIT: robust to gigantic evergreen herbs forming large
colonies, rhizome short, thick, hypogeal, vigorously stoloniferous. LEAVES: several. PETIOLE: very long, 4–6 angled,
aculeate along angled ridges, weakly geniculate at apex,
sheath short. BLADE: deeply sagittate, sometimes weakly
hastate, to over 1m long, coriaceous, ± erect; basal ribs
well-developed, primary lateral veins pinnate, long arcuate
towards apex of each leaf division and running into marginal vein, higher order venation reticulate.
INFLORESCENCE: solitary, appearing with leaves. PEDUNCLE:
subequal to petiole and similar in appearance. SPATHE:
erect, ovate, ± convolute in lower third, gaping at anthesis,
striped purple and yellow within, persistent. SPADIX: sessile to stipitate, cylindric, obtuse, shorter than spathe,
flowering sequence basipetal. FLOWERS: bisexual, perigo-
27. Lasimorpha
C
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G
B
A
K
N
H
D
M
J
E
C
F
L
Plate 26. Cyrtosperma. A, inflorescence × 2.3; B, flower, longitudinal section × 8; C, infructescence × 2/3; D, seed, side view × 6; E, leaf ×
2/3; F, base of plant × 2/3; G, habit × 1/8; H, leaf × 2/3; J, base of petiole × 2/3; K, inflorescence × 2/3; L, detail of spadix × 4; M, flower, longitudinal section × 8; N, infructescence × 2/3. Cyrtosperma cuspidispathum: A–B, NGF 10241 (K & Kew spirit collection 18946); C–D, Hay s.n.
(Kew spirit collection 45943); C. beccarianum: E, Reksodihardjo 412 (K); F, van Royen 4792 (K); C. macrotum: G, Aroids of Papua New Guinea
pl. x, 3 (1990); C. merkusii: H, Lobb s.n. (K); J, Nicolson 1217 (K); L–M, Bogner 1510 (Kew spirit collection 45187); N, Reksodihardjo 311 (K).
L A S I O I D E A E : C Y RTO S P E R M A
139
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H
E
F
D
G
B
C
J
A
Plate 27. Lasimorpha. A, base of plant showing stolons × 2/3; B, leaf × 2/3; C, inflorescence × 2/3; D, detail of spadix × 4; E, flower, tepals
removed × 8; F, gynoecium, longitudinal section × 8; G, stamens, top view × 8; H, infructescence × 2/3; J, seed, side view × 5. Lasimorpha
senegalensis: A, Bogner 691 (K & Kew spirit collection 29047.472); B, Leeuwenberg 1873 (K); C, Bogner 691 (Kew spirit collection 57526);
D–J, Meikle 642 (Kew spirit collection 25024).
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THE GENERA OF ARACEAE
26b Tribes & Genera Acro 17/7/97 17:13 Page 141
niate; tepals 4(–5), free, fornicate. STAMENS: 4(–5), filaments free or partially to completely connate, anthers
partially exserted from tepals at anthesis, connective slender, thecae dehiscing by short apical slit. POLLEN:
monosulcate, ellipsoid, small (22 µm.), exine subreticulate,
apertural exine psilate. GYNOECIUM: ovoid-ellipsoid to
oblong, ovary 1-locular, ovules 4–6(–8), campylotropous,
placenta single, ± prominent, parietal and basal, stylar
region short, somewhat narrowed, stigma discoid-hemispheric. BERRY: irregularly globose, 1–4-seeded, red. SEED:
strongly curved, weakly strophiolate, testa hard, brown,
warty to spiny, embryo rather large, curved, endosperm
present but only as a few cell layers. See Plates 27, 112B.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 1 sp.; tropical west and central Africa:–
Angola, Benin, Cameroon, Central African Republic, Chad,
Congo, Equatorial Guinea (Bioko, Rio Muni), Gabon,
Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia,
Nigeria, Senegal, Sierra Leone, Zaïre.
ECOLOGY: tropical swamp forest, open wet areas; helophyte along streams, in ditches and ponds, in forest gaps,
often very abundant.
ETYMOLOGY: Lasia and Greek morphê (shape).
TAXONOMIC ACCOUNTS: Engler (1911, as Cyrtosperma),
Knecht (1983), Hay (1988, 1992a).
C
veins mostly arising near petiole insertion, long-arcuate
towards division apex and running into margin, higher order
venation reticulate. INFLORESCENCE: solitary. PEDUNCLE:
subequal to petiole and similar in appearance. SPATHE: ovatelanceolate, fully expanded, persistent, red brown. SPADIX:
shorter or equalling spathe, cylindric, stipitate, stipe basally
adnate to spathe, flowering sequence basipetal. FLOWERS:
bisexual, perigoniate; tepals 4–6, fornicate. STAMENS: 4–6,
free, filaments oblong, flattened, connective slender, thecae
ellipsoid, dehiscing by longitudinal slit. POLLEN: monosulcate,
ellipsoid-oblong, small (mean 18 µm.), exine scabrate or verruculate, minutely foveolate between verruculae.
GYNOECIUM: cylindric to obovoid, ovary 1-locular, ovule 1,
anatropous, placenta parietal to subbasal, stigma discoidhemispheric. BERRY: ovoid to ellipsoid, smooth, strongly
exserted at maturity, very prominent and thicker than spadix,
red. SEED: curved, ± spherical, testa thin, hard, smooth, dark
brown, embryo curved, endosperm present but only as a few
cell layers. See Plates 28, 112C.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 1 sp.; Malay Archipelago:– Indonesia
(Sumatra), Malaysia (Sarawak, Peninsula).
ECOLOGY: tropical humid forest, usually peat swamp forest;
helophyte, along streams.
ETYMOLOGY: Greek pous, podos (foot) and Lasia; refers to the
± basal placentation of the ovule and the resemblance to Lasia.
TAXONOMIC ACCOUNTS: Engler (1911), Hay (1988, 1992a).
28. Podolasia
Podolasia N.E. Brown Gard. Chron., ser.2, 18: 70 (1882).
TYPE: P. stipitata N.E. Brown
HABIT: evergreen herbs, solitary or forming small clumps, rhizomatous, aerial stem erect to decumbent, internodes distinct,
unarmed. LEAVES: several. PETIOLE: long, geniculate apically, aculeate, spines either patent or pointing downwards,
sheath short. BLADE: unarmed, sagittate to hastate or almost
tripartite, coriaceous, posterior divisions ± equalling anterior,
sometimes longer; basal ribs well-developed, primary lateral
28. Podolasia
C
29. Lasia
Lasia Loureiro, Fl. Cochinch. 64, 81 (1790). TYPE: L. aculeata
Lour. (= L. spinosa (L.) Thwaites).
SYNONYM: [Lasius Hasskarl, Cat. Bogor. 59 (1844),
orth.var.]
HABIT: clump- and colony-forming evergreen herbs,
stoloniferous, stem thick, aculeate or unarmed (L. concinna),
erect to decumbent, green, epigeal or submersed, internodes
29. Lasia
LASIOIDEAE : LASIA
141
26b Tribes & Genera Acro 17/7/97 17:13 Page 142
C
D
E
A
G
F
B
Plate 28. Podolasia. A, habit × 2/3; B, detail of spadix × 5; C, flower × 10; D, flower, nearside tepals removed × 10; E, gynoecium, longitudinal section × 10; F, infructescence, × 2/3; G, seed, side view × 3. Podolasia stipitata: A, Corner 30898 (K); Kunstler (Dr King’s collector)
5499 (K); Parris 10979 (K); B, Corner 30898 (K); C–G, Parris 10979 (K).
142
THE GENERA OF ARACEAE
26b Tribes & Genera Acro 17/7/97 17:13 Page 143
K
J
F
B
H
A
D
G
E
C
Plate 29. Lasia. A, leaf × 2/3; B, leaf × 2/3; C, leaf and base of plant with adventitious shoots, large portion of petiole removed × 2/3; D,
habit × 1/15; E, inflorescence × 2/3; F, tranverse section of spiral portion of spathe × 2/3; G, detail of spadix × 5; H, flower, longitudinal section × 7; J, infructescence × 2/3; K, seed, side view × 5. Lasia spinosa: A, Cult. Kew (K); B, Hooker & Thomson s.n. (K); C, Clarke 7934 (K);
Bogner 428 (Kew spirit collection 46984); D, Forman & Blewett 975 (Kew slide collection); E–H, Mayo 133 (Kew spirit collection 47735); J–K,
Hooker & Thomson s.n. (K); Boyce 340 (Kew slide collection).
LASIOIDEAE : LASIA
143
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relatively long or short. LEAVES: several. PETIOLE: long,
aculeate, weakly geniculate apically, sheath relatively short.
BLADE: sagittate to hastate-sagittate when juvenile, adult
blade deeply pinnatifid in anterior division, posterior divisions pedatifid, sometimes simple, adult blade rarely entire,
or bipinnatifid (L. concinna), major veins aculeate on lower
surface; primary lateral veins pinnate in anterior division,
pedate in posterior divisions, primary lateral veins of each
pinna forming submarginal collective vein in pinnatifid
leaves, or running into marginal vein in simple leaves, higher
order venation reticulate. INFLORESCENCE: solitary. PEDUNCLE: subequal to petiole, aculeate as petiole. SPATHE: linear,
very long and narrow (L. spinosa) or broader (L. concinna),
very thick and spongy, spirally twisted, marcescent or deciduous, basal part enclosing spadix, gaping at anthesis.
SPADIX: shortly cylindric, obtuse, sessile. FLOWERS: bisexual, perigoniate; tepals usually 4, more rarely 6, fornicate.
STAMENS: 4(–6), free, filaments broad, connective slender,
thecae ellipsoid, dehiscing by longitudinal slit. POLLEN:
monosulcate, ellipsoid, medium-sized (mean 27 µm.), exine
reticulate, psilate along aperture margins. GYNOECIUM:
ovoid to ellipsoid, ovary 1-locular, ovule 1, anatropous, funicle very short, placenta apical, stylar region well developed,
shortly attenuate to cylindric, stigma discoid-hemispheric.
BERRY: borne in cylindric infructescence, crowded, quadrangular, apically densely muricate to spinose or smooth,
1-seeded, green. SEED: large, compressed-obovoid, testa
thin, brown, hard, somewhat rugose, embryo large, somewhat curved, endosperm present but only as a single cell
layer. See Plates 29, 112D.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 2 spp.; tropical southeast Asia, Malay
Archipelago:- Bangladesh, Brunei, Burma, Cambodia, China
(Guandong, Guangxi, Hainan, Hong Kong, Taiwan,
Yunnan), India, Indonesia, Laos, Malaysia (Borneo,
Peninsula), Nepal, Papua New Guinea, Singapore, Sri Lanka,
Thailand, Vietnam.
ECOLOGY: tropical humid forest; helophytes, wet places in
forest, open swamps, along streams, rice fields, tidal flats.
ETYMOLOGY: Greek lasios (shaggy), refers to the densely
spiny stems.
TAXONOMIC ACCOUNTS: Engler (1911), Sivadasan (1982),
Hay (1988, 1990b, 1992a).
C
30. Urospatha
Urospatha Schott, Aroideae 3 (1853). LECTOTYPE: U.
sagittifolia (Rudge) Schott (“sagittaefolia ”, Pothos sagittaefolia Rudge; see Nicolson 1967).
SYNONYMS: Urophyllum K. Koch in Berliner Allg.
Gartenzeitung 25: 173 (1857, non Jack ex Wallich 1824);
Urospathella Bunting in Phytologia 65: 391 (1988).
HABIT: robust to slender evergreen herbs, solitary to clumpforming, rhizome subterranean, horizontal or vertical,
spongy. LEAVES: few, basal, ± erect. PETIOLE: long, spongy,
smooth or scabrid-verrucose, sometimes angled, often variegated, apical geniculum absent or only very weakly
developed, sheath long to short. BLADE: deeply sagittate or
subtripartite to hastate, posterior divisions usually longer
than anterior division, rarely blade lanceolate-linear and
lacking posterior divisions (U. wurdackii); basal ribs welldeveloped, primary lateral veins of both anterior and
posterior divisions pinnate, long-arcuate towards division
144
THE GENERA OF ARACEAE
30. Urospatha
apex and running into marginal vein, higher order venation
reticulate. INFLORESCENCE: solitary, rarely 2 in each floral
sympodium. PEDUNCLE: equal to or longer than leaf, similar in appearance to petiole. SPATHE: erect, persistent,
convolute below, gaping above, apically long-acuminate,
usually spirally twisted, sometimes flattened. SPADIX:
shortly stipitate or sessile, usually much shorter than spathe,
cylindric to subcylindric, obtuse. FLOWERS: bisexual,
perigoniate; tepals 4–6, fornicate. STAMENS: 4–6, free, filaments broadish, a little compressed, connective slender,
thecae ellipsoid, dehiscing by apical slit. POLLEN: monosulcate, ellipsoid, medium-sized (mean 26 µm., range 25–28
µm.), exine subreticulate, subrugulate to reticulate, apertural
exine psilate. GYNOECIUM: ovoid, ovary 1–2-locular,
ovules (1–)2–4 or more per locule, anatropous, placenta
axile in 2-locular ovaries, basal in 1-locular ovaries, stylar
region a little narrower than ovary, stigma broad, circular,
discoid. BERRY: obovoid, 1–5(–8)-seeded, green to greenish yellow. SEED: curved, testa hard, brown, thickish,
strongly warty, or spiny or crested, embryo curved,
endosperm present but only as a very thin layer about 2
cells thick. See Plates 30, 113A.
CHROMOSOMES: 2n = 52.
DISTRIBUTION: ca. 10 spp. (T. Croat pers. comm.); tropical
America:– Brazil, Colombia, Costa Rica, ?Ecuador, French
Guiana, Guatemala, Guyana, Nicaragua, Panama, Peru,
Surinam, Venezuela.
ECOLOGY: tropical humid forest and wetlands; helophytes,
open aquatic habitats, swamps, along streams, brackish water.
NOTE: Urospatha wurdackii (syn. Urospathella wurdackii) is
notable for its small stature, linear-lanceolate leaves, and
very slender spathe.
ETYMOLOGY: Greek “oura” (tail) and “spathê” (spathe).
TAXONOMIC ACCOUNTS: Engler (1911), Bunting (1988,
1989a), Hay (1992a).
26b Tribes & Genera Acro 17/7/97 17:14 Page 145
N
G
M
L
K
F
B
A
D
J
C
H
E
Plate 30. Urospatha. A, habit × 1/10; B, leaf × 2/3; C, inflorescence × 2/3; D, detail of spadix × 4; E, flower, longitudinal section × 10; F,
infructescence showing persistent spathe × 2/3; G, seed, side view × 5; H, leaf × 2/3; J, leaf × 2/3; K, inflorescence × 2/3; L, diagrammatic
longitudinal section of inflorescence to show partial spathe/spadix fusion × 2/3; M, detail of spadix × 4; N, flower, longitudinal section × 10.
Urospatha sagittifolia : A, Mayo (Kew slide collection); U. sagittifolia: B, Jenman 5777 (K); C, Bogner s.n. (Kew spirit collection 29047.469);
D–G, Bogner 580 (Kew spirit collection 29047.191); U. angustiloba : H, Spruce 3761 (K); U. wurdackii: J, Huber, Tillet & Davidse 3721 (K);
K–N, Davidse, Huber & Tillet 17085 (K & Kew spirit collection 57275).
LASIOIDEAE : UROSPATHA
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C
VI. Subfamily Calloideae
VII. Subfamily Aroideae
Subfamily Calloideae Endlicher, Gen. Pl. 239 (1837,
“Callaceae”).
Subfamily Aroideae
Laticifers present, simple, articulated; trichosclereids absent;
rooted aquatic, stem rhizomatous; leaves distichous; petiole not geniculate apically, sheath long; blade cordate,
venation parallel-pinnate, uniformly fine; spathe fully
expanded, elliptic- to ovate-lanceolate, persistent; flowers
bisexual, perigone absent, 3-merous; stamens 6 (or more),
thecae dehiscing by longitudinal slit, pollen dicolpate;
ovary 1-locular, ovules 6–9, anatropous, placenta basal;
endosperm copious.
C
31. Calla
Calla L., Sp. Pl. 968 (1753). TYPE: C. palustris L.
SYNONYMS: Provenzalia Adanson, Fam. 2: 469 (1763);
Aroides Heister ex Fabricius, Enum., ed. 2, p. 42 (1763);
Callaria Rafinesque in Amer. Monthly Mag. & Crit. Rev. 2: 267
(1818).
Laticifers present, simple, articulated. HABIT: seasonally
dormant herb with repent or submersed, green, rhizomatous stem, rooting at nodes. LEAVES: distichous. PETIOLE:
sheath long, with long, free, ligulate apex. BLADE: cordate
to broadly cordate, rounded, cuspidate-apiculate; primary
lateral veins not differentiated, higher order venation parallel-pinnate. INFLORESCENCE: solitary. PEDUNCLE: erect,
as long or longer than petiole. SPATHE: fully expanded,
elliptic- or ovate-lanceolate, acuminate, shortly decurrent,
persistent, white within at anthesis, green without. SPADIX:
stipitate, cylindric, obtuse. FLOWERS: bisexual, often male
at spadix apex, perigone absent. STAMENS: ca. 6, free,
sometimes more, filaments somewhat flattened, anthers
short, connective slender, short, thecae ellipsoid, opposite, dehiscing by longitudinal slit. POLLEN: diaperturate,
globose, small (mean 23 µm.), exine foveolate, apertural
exine verrucate. GYNOECIUM: shortly ovoid, 1-locular,
ovules 6–9, anatropous, oblong, funicles short, placenta
basal, stylar region attenuate, stigma small, subhemispheric.
BERRY: spheroid-conic, several-seeded, red. SEED: tereteoblong, testa thick, scrobiculate towards chalaza,
sulcate-striate towards micropyle, raphe prominent, embryo
axile, elongate, endosperm copious. See Plates 31, 113B.
CHROMOSOMES: 2n = 36, 54, 72.
DISTRIBUTION: 1 sp.; circumboreal:– Austria, Belgium,
Canada, China, Croatia, Czech Republic, Denmark, Estonia,
Finland, France, Germany, ?Hungary, ?Japan, Korea (N.),
Netherlands, Norway, Poland, Romania, Russia, Slovak
Republic, Slovenia, Sweden, Switzerland, Turkey, USA.
ECOLOGY: in forest swamps, often between forest margins
and raised bogs, often with Sphagnum, up to 1270m alt.;
creeping helophyte in streams and ponds.
ETYMOLOGY: classical name, first used by Pliny for two different kinds of aroids; perhaps from the Greek kallos
(beauty).
TAXONOMIC ACCOUNTS: Krause (1908), Dudley (1937),
Huttleston (1953), Riedl (1977–1979), Topic & Ilijanic (1989).
146
THE GENERA OF ARACEAE
C
Laticifers present (except Pistieae, Stylochaetoneae, Zamioculcadeae), usually simple and articulated, more rarely
anastomosing (in Caladieae, Colocasieae, Zomicarpeae); trichosclereids absent; stem most frequently hypogeal, tuberous
or rhizomatous, less often aerial, rarely hemiepiphytic
climbers or epiphytes (Culcasieae, Philodendreae,
Syngonium), very rarely floating aquatics (Pistieae); petiole
usually not geniculate apically (except Anubiadeae, Bognera,
Culcasieae, Zamioculcadeae, rarely in Philodendreae and
Homalomeneae); higher order leaf venation more usually
reticulate, less often parallel-pinnate (in Aglaonemateae,
Anubiadeae, Colocasieae, Dieffenbachia, Homalomeneae,
Peltandreae, Philodendreae, Schismatoglottideae,
Zantedeschieae); spathe usually differentiated into lower,
convolute tube and upper, gaping blade; flowers unisexual,
perigone absent (except Stylochaetoneae, Zamioculcadeae);
pollen inaperturate (except Zamioculcadeae and sometimes
Stylochaetoneae).
Tribe Zamioculcadeae
C
Tribe Zamioculcadeae Engler in Nova Acta Acad. Leopold.Carol. 39: 141 (1876, “Zamioculcaseae ”).
Laticifers absent; seasonally dormant or evergreen
(Zamioculcas), stem hypogeal; petiole geniculate; leaf blade
compound; spathe convolute basally, blade reflexed at
anthesis; spadix subequalling spathe, female zone separated
from male by short, constricted zone of sterile flowers, male
zone cylindric to clavate, fertile to apex; flowers unisexual,
perigoniate; tepals 4, free, ± prismatic; stamens 4, surrounding ± clavate pistillode, filaments free, (connate in
Gonatopus), anther terminal, connective inconspicuous,
pollen extended-monosulcate to fully zonate, extruded in
strands; ovary 2-locular, ovules 1 per locule, hemianatropous, placenta axile to basal, style short, distinct, stigma
large, hemispheric-discoid; berries and seeds large, testa
smooth, endosperm absent.
32. Zamioculcas
Zamioculcas Schott, Syn. Aroid. 71 (1856). TYPE: Z. loddigesii Schott, nom. illeg. (Caladium zamiaefolium Loddiges,
Z. zamiifolia (Loddiges) Engler).
HABIT: seasonally dormant or evergreen herb with short,
very thick rhizome. LEAVES: few to many, erect, leaflets
deciduous during dormancy leaving persistent petiole. PETIOLE: terete, base greatly thickened and succulent, geniculate
at apex, sheath ligulate, free almost to the base, very short,
inconspicuous. BLADE: pinnatisect, leaflets oblong-elliptic,
thickly coriaceous, capable of rooting at base once shed and
forming new plants; primary lateral veins of each leaflet pinnate, running into marginal vein, higher order venation
reticulate. INFLORESCENCE: 1–2 in each floral sympodium,
held at ground level. PEDUNCLE: very short. SPATHE: entirely
persistent to fruiting stage, slightly constricted between tube
and blade, green without, whitish within, tube convolute,
blade longer than tube, expanded and horizontally reflexed
C
26b Tribes & Genera Acro 17/7/97 17:15 Page 147
B
F
C
D
A
E
Plate 31. Calla. A, habit × 2/3; B, spadix × 4; C, flower × 15; D, gynoecium, longitudinal section × 15; E, infructescence × 2/3; F, seed, side
view × 10. Calla palustris: A, Bogner s.n. (Kew spirit collection 58031, 58904); B–F, Bogner 2117 (Kew spirit collection 57571).
31. Calla
CALLOIDEAE : CALLA
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26b Tribes & Genera Acro 17/7/97 17:15 Page 148
C
B
D
A
E
J
H
K
L
G
Q
P
N
F
M
Plate 32. Zamioculcas. A, habit × 1/3; B, leaflet × 2/3; C, leaflet with adventitious tuberlet × 2/3; D, first leafy shoot from adventitious tuberlet × 2/3; E, base of leaf showing swollen petiole × 2/3; F, inflorescence × 1; G, spadix × 1; H, male flower, nearside tepal removed × 8; J,
detail of male flowers × 5; K, sterile flower, nearside tepal removed × 8; L, detail of sterile flowers × 5; M, gynoecium, longitudinal section
× 8; N, detail of female flowers × 5; P, infructescence, longitudinal section × 1; Q, seed, side view × 6. Zamioculcas zamiifolia: A–M, Bogner
s.n. Cult. Kew 1967–49401 (Kew spirit collection 49776, 29047.131 & 58712); P–Q, Faden & Faden 77/377 (K).
148
THE GENERA OF ARACEAE
26b Tribes & Genera Acro 17/7/97 17:15 Page 149
SYNONYMS: Heterolobium A. Peter, Nachr. Ges. Wiss.
Göttingen, Math.-Phys. Kl. 1929 (3): 211, 221 (1930);
Microculcas A. Peter, Nachr. Ges. Wiss. Göttingen, Math.Phys. Kl. 1929 (3): 212, 222 (1930).
32. Zamioculcas
at anthesis. SPADIX: sessile, female zone subcylindric, separated from male zone by short constricted zone bearing sterile
flowers, male zone cylindric, ellipsoid to clavate, fertile to
apex. FLOWERS: unisexual, perigoniate; tepals 4, in two
whorls, decussate. MALE FLOWER: tepals subprismatic, apex
thickened, stamens 4, free, shorter than tepals, filaments free,
oblong, thick, somewhat flattened, anthers introrse, connective slender, thecae ovate-ellipsoid, dehiscing by apical slit,
pistillode clavate, equalling tepals. POLLEN: extruded in
strands, extended monosulcate to perhaps fully zonate, ellipsoid, large (mean 60 µm.), exine thick, fossulate-foveolate,
apertural exine verrucate. STERILE FLOWERS: each consisting
of 4 tepals surrounding a clavate pistillode. FEMALE FLOWER:
tepals strongly thickened apically, staminodes lacking, gynoecium equalling tepals, ovary ovoid, 2-locular, ovules 1 per
locule, hemianatropous, funicle very short, placenta axile
near base of septum, stylar region attenuate, stigma large,
discoid-capitate. BERRY: depressed-globose with furrow at
septum, 1–2-seeded, surrounded by persistent tepals, white,
infructescence ellipsoid. SEED: ellipsoid, testa smooth, brown,
raphe conspicuous, embryo large, rich in starch, endosperm
nearly absent, present only as a few cell layers at chalazal end.
See Plates 32, 113C.
CHROMOSOMES: 2n = 34.
DISTRIBUTION: 1 sp.; tropical east and subtropical southeast
Africa:– Kenya, Malawi, Mozambique, South Africa (Natal),
Tanzania (incl. Pemba, Zanzibar), Zimbabwe.
ECOLOGY: tropical moist forest, savannas; geophytes on
forest floor or in stony ground.
ETYMOLOGY: Zamia (genus of cycads) and Greek kolokasia (from Middle Eastern “qolqas”); perhaps in reference to the
pinnately compound leaves, in fanciful comparison to Zamia.
TAXONOMIC ACCOUNTS: Engler (1905), Obermeyer & Strey
(1969), Mayo (1985a).
C
HABIT: Seasonally dormant herbs, stem subterranean, a subglobose tuber or a cylindric, horizontal rhizome. LEAF:
solitary, rarely pilose or scabrous, preceded by lanceolate
cataphylls. PETIOLE: geniculate basally or centrally. BLADE:
usually trisect, rarely not (G. petiolulatus), primary divisions
trifid to trisect or pinnatifid, or pinnatisect to quadri-pinnatifid, pinnae geniculate at junction with rachis, ultimate lobes
varying from linear to broad-elliptic, often decurrent; primary
lateral veins of each lobe pinnate, forming arching submarginal collective vein, higher order venation reticulate.
INFLORESCENCE: 1–4 in each floral sympodium, appearing
before or with leaves, subtended by several cataphylls.
PEDUNCLE: erect, very short to long. SPATHE: constricted
between tube and blade, tube convolute, subglobose, cylindric or suburceolate, blade oblong to elliptic, reflexed at
anthesis, marcescent. SPADIX: subequal to spathe, female
zone subcylindric, separated from male zone by very short,
constricted zone of sterile flowers, male zone longer than
female, cylindric to clavate, fertile to apex. FLOWERS: unisexual, perigoniate; tepals 4(–6), in 2 decussate whorls,
fleshy, truncate to ± cucullate. MALE FLOWER: stamens with
connate filaments forming tube around central, cylindric to
clavate pistillode, often exserted above tepals at anthesis,
connective slender, thecae dehiscing by apical pore.
POLLEN: extruded in strands, extended monosulcate or fully
zonate, hamburger-shaped, large (mean 76 µm., range 73–79
µm.), exine thick, foveolate, the foveolae scattered or
grouped in fossulae, apertural exine psilate to ± verrucate.
FEMALE FLOWER: usually lacking staminodes, exceptionally
1 staminode present, ovary 2-locular, ovules 1 per locule,
anatropous, funicle very short to almost absent, placenta
basal-axile, stylar region thick, somewhat attenuate, stigma
large, discoid-hemispheric. BERRY: ovoid-ellipsoid, 1–2seeded, red or orange to yellow, or whitish. SEED:
ovoid-ellipsoid, testa thin, smooth, embryo large, plumule
lateral, superficial, endosperm absent. See Plates 33, 113D.
33. Gonatopus
Gonatopus J.D. Hooker ex Engler in A. & C. De Candolle,
Monogr. Phan. 2: 208 (1879). TYPE: G. boivinii (Decaisne)
Engler (Zamioculcas boivinii Decaisne).
33. Gonatopus
Z A M I O C U L C A D E A E : G O N ATO P U S
149
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B
D
EE
DD
M
Y
W
Z
E
X
AA
F
V
FF
A
C
T
U
K
H
GG
N
S
P
R
Q
CC
J
G
L
BB
Plate 33. Gonatopus. A, habit × 1/2; B, stamens, perigone removed × 5; C, detail of male flower × 5; D, gynoecium, longitudinal section
× 5; E, infructescence × 2/3; F, seed, front view × 5; G, habit × 1/2; H, stamens, perigone removed × 5; J, detail of female flower × 5; K,
gynoecium, longitudinal section × 5; L, habit × 1/2; M, leaflet × 1; N, inflorescence × 1; P, detail of male flowers × 2; Q, detail of female flowers × 2; R, stamens, perigone removed × 5; S, detail of male flower × 5; T, gynoecium, longitudinal section × 5; U, single tepal, three quarter
view × 5; V, habit × 1/2; W, stamens, perigone removed × 5; X, male flower × 5; Y, gynoecium, longitudinal section × 5; Z, infructescence ×
2/3; AA, seed, side view × 2; BB, habit × 1/2; CC,, inflorescence, lower part of spathe removed to display spadix; DD, stamens, perigone
removed × 5; EE, single tepal, three quarter view × 5; FF, male flower × 5; GG, gynoecium, longitudinal section × 5. Gonatopus angustus:
A, Nuvunga & Conjo 385 (K); B–D, Cult. Kew 1971–02232 (Kew spirit collection 45233); E, Mogg 30003 (K); F, Bogner s.n. (Kew spirit collection 45229); G. petiolulatus: G, Vollesen 4788 (K); H–K, Bogner 241 (Kew spirit collection 37580); G. clavatus: L–M, Milne-Redhead & Taylor
7670 (K & Kew spirit collection 22034); N–U, Milne-Redhead & Taylor 7670 (Kew spirit collection 22034); G. marattioides: V–AA, Bogner
247 (Kew spirit collection 45222 & 52143); G. boivinii: BB, Bullock 1323 (K); CC–GG, Bogner 127 (Kew spirit collection 29047.481 ).
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CHROMOSOMES: 2n = 34, 68.
DISTRIBUTION: 5 spp.; tropical east and subtropical southeast Africa:– Kenya, Malawi, Mozambique, South Africa
(Natal, Transvaal), Tanzania (incl. Pemba, Zanzibar), Zaïre,
Zambia, Zimbabwe.
ECOLOGY: tropical evergreen forest; geophytes, on forest
floor, also in rocky crevices with humus deposits.
NOTE: The leaf blade of G. petiolulatus, in which the lower
pinnae are reduced to irregular, linear rudimentary leaflets, is
intermediate in form between Gonatopus and Zamioculcas. In
G. boivinii, the fallen leaflets may root and form new plants.
ETYMOLOGY: Greek gony, gonatus (knee) and pous, podos
(foot); in reference to the petiole geniculum in G. boivinii.
TAXONOMIC ACCOUNTS: Engler (1905), Obermeyer &
Bogner (1979), Mayo (1985a).
C
Tribe Stylochaetoneae
Tribe Stylochaetoneae Schott, Syn. Aroid. 132 (1856,
“Stylochitoneae”).
Laticifers absent; stem hypogeal, rhizomatous, roots often
very thick, fleshy; higher order leaf venation reticulate; spathe
tube margins connate; spadix mostly hidden within spathe,
fertile to apex; flowers unisexual, perigoniate; perigone a
single, cup-like (urceolate) structure; male flower usually
with central peg-like pistillode, stamen filaments long, slender, filiform, anthers terminal, dehiscing by longitudinal slits,
connective slender, pollen sometimes monosulcoidate, otherwise inaperturate; ovary 1–4 locular, ovules 1–many per
locule, anatropous, placenta basal, parietal or axile, style
thick, exserted from perigone, stigma capitate to thickly discoid; endosperm copious.
C
34. Stylochaeton
Stylochaeton Leprieur in Ann. Sci. Nat., ser. 2, Bot., 2: 184
(1834). TYPE: S. hypogeum Leprieur
SYNONYM: [Stylochiton Schott, Aroideae 10 (1855),
orth.var.].
Laticifers absent. HABIT: seasonally dormant or evergreen
herbs, rhizome subterranean, horizontal to erect, sometimes
stoloniferous, roots thick, spindle-shaped, often very fleshy,
almost tuberous. LEAVES: 1 to several, cataphylls often conspicuously mottled and apically auriculate, sometimes
persistent as fibrous mass. PETIOLE: sheath short to long,
often purplish-spotted or banded. BLADE: lanceolate, ovate,
± rounded, cordate-sagittate, sagittate, hastate-sagittate or
hastate; primary lateral veins pinnate or mostly arising basally,
long-arcuate and running into marginal vein, lowermost primaries sometimes retrorse and then ascending, higher order
venation reticulate. INFLORESCENCE: 1–4 in each floral sympodium, appearing before or with leaves, borne at or partially
below ground level. PEDUNCLE: short, much shorter than
petiole. SPATHE: erect, marcescent; tube: margins connate,
often ventricose at extreme base, sometimes constricted
between a lower and an upper inflated zone, rarely entire
spathe narrowly cylindric; blade: lanceolate-elliptic, ± gaping
or opening only by narrow longitudinal slit, often much
thickened. SPADIX: free, shorter than spathe, female zone
densely flowered, sometimes contiguous with male zone,
often separated by axis bearing a few (to many) sterile or
bisexual flowers, male zone fertile to apex. FLOWERS: unisexual, perigoniate, borne in single basal whorl or in spirals;
perigone a single cup-like (urceolate) structure. MALE
FLOWER: perigone often with very thick, fleshy margins,
stamens 2–7, free, filaments filiform, long, rarely much thickened apically, connective slender, sometimes slightly
thickened, thecae oblong, dehiscing by longitudinal slit, pistillode central, cylindric to conoid, sometimes absent.
POLLEN: inaperturate, or sometimes vestigially monosulcate,
ellipsoid, large (mean 53 µm., range 43–58 µm.), exine foveolate-reticulate or subreticulate. FEMALE FLOWER: perigone
usually greatly thickened and sticky-glandular or farinaceous
on upper surface, ovary 1–4-locular, ovules 1–many per
locule, anatropous, placenta basal, parietal or axile, stylar
region thick, ± cylindric, exserted beyond perigone, stigma
capitate to broadly discoid and massive. BERRY: borne at or
below ground level in globose to cylindric infructescence,
often rugose, fleshy, 1–few-seeded. SEED: ovoid to ellipsoid, slightly compressed, testa black, thin, costate, embryo
axile, elongate, endosperm copious. See Plates 34, 114A.
CHROMOSOMES: 2n = 28, 56.
DISTRIBUTION: 17 spp.; tropical and southeast subtropical
Africa:– Angola, Benin, Burkina Faso, Cabinda, Cameroon,
Central African Republic, ?Chad, Equatorial Guinea (Bioko,
Rio Muni), Ethiopia, Gabon, Ghana, Guinea, Ivory Coast,
Kenya, Liberia, Malawi, Mali, Mozambique, Nigeria, Senegal,
Sierra Leone, Somalia, South Africa (Transvaal, Natal), Sudan,
Swaziland, Tanzania, Togo, Uganda, Zaïre, Zambia, Zimbabwe.
ECOLOGY: tropical humid forests (evergreen species, e.g. S.
zenkeri), tropical savannas and deciduous forests (seasonally
dormant species, e.g. S. natalensis); geophytes.
NOTES: Engler (1920a) recognized 2 sections:– sect.
Stylochaeton (syn. sect. Cyclogyne) and sect. Spirogyne.
ETYMOLOGY: Greek stylos (style) and chitôn (tunic); refers
to connate perigone surrounding gynoecium.
TAXONOMIC ACCOUNTS: Engler (1920a), Knecht (1983),
Bogner (1984c), Mayo (1985a), Ntépé-Nyame (1988), Malaisse
& Bamps (1994).
34. Stylochaeton
S T Y L O C H A E TO N E A E : S T Y L O C H A E TO N
151
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F
D
A
J
E
K
G
B
C
H
L
Plate 34. Stylochaeton. A, habit × 1/2; B, flowering habit × 2/3; C, spadix × 2; D, habit × 1/2; E, habit × 1/2; F, infructescence × 1; G, habit
× 1/2; H, spadix × 2; J, male flower × 8; K, female flower × 5; L, gynoecium, longitudinal section × 5. Stylochaeton lancifolius: A, Andrews
732 (K); B–C, Meikle 1294 (K & Kew spirit collection 27685); Schweinfurth 199 (K); Synge 220 (K & Kew spirit collection 58038); S. zenkeri:
D, Letouzey 14413 (K); S. borumensis: E, Greenway & Kanuri 12751 (K); Verdcourt 3224A (K); S. bogneri: G, Bogner 145 (K); Lucas 253 (K);
H–L, Bogner 148 (Kew spirit collection 7707).
152
THE GENERA OF ARACEAE
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C
Tribe Dieffenbachieae
Tribe Dieffenbachieae Engler in Nova Acta Acad. Leopold.Carol. 39: 148 (1876).
SYNONYM: Tribe Bognereae Mayo & Nicolson in Taxon
33 (4): 689 (1984).
Laticifers present, simple, articulated; terrestrial to helophytic, stem aerial, internodes distinct; spadix: female zone
entirely adnate to spathe, laxly flowered, sterile male flowers (synandrodes) usually present between female and
male zones; flowers unisexual, perigone absent; stamens
connate into a truncate, prismatic synandrium, fused connectives strongly thickened, thecae lateral, pollen grains
large; female flowers distant from one another, ovary 1–3
locular, ovules 1 per locule, anatropous, placenta basal or
basal-axile.
C
35. Dieffenbachia
Dieffenbachia Schott in Wiener Z. Kunst 1829 (3): 803
(1829). TYPE: D. seguine (Jacquin) Schott (“seguinum”; Arum
seguine Jacquin).
SYNONYMS: Seguinum Rafinesque, Fl. Tell. 3: 66 (1837,
“1836”); Maguirea A.D. Hawkes in Bull. Torrey Bot. Club 75:
635 (1948).
HABIT: evergreen herbs, sometimes robust, stems erect to
decumbent, sometimes ± rhizomatous, rooting proximally,
erect and unbranched distally, internodes distinct, green,
smooth, with conspicuous annular leaf scars. LEAVES:
numerous, forming an apical crown. PETIOLE: sheath more
than half as long as petiole or reaching blade. BLADE:
oblong-ovate, elliptic to oblanceolate, dark to light green or
sometimes variegated with white, silver, yellow or various
shades of green; midrib thick, sulcate or prominent on
upper surface, primary lateral veins pinnate, sometimes
only weakly differentiated, running into margin, secondary
laterals parallel-pinnate, connected by transverse tertiary
veins. INFLORESCENCE: (1–)2-several in each floral sympodium, cataphylls short and usually inconspicuous.
PEDUNCLE: shorter than petiole. SPATHE: persistent,
slightly or distinctly constricted between tube and blade,
green, lower part convolute into a usually rather long, persistent tube which splits longitudinally in fruit, upper part
expanded into a short, erect or recurved blade. SPADIX:
slightly shorter than spathe, female zone entirely adnate to
spathe, enclosed within tube, laxly flowered, separated
from male zone by subnaked axis with a few, scattered
sterile male flowers with reduced staminodes, rarely fertile
zones contiguous (D. humilis), male zone fertile to apex,
free, subcylindric, densely flowered, erect. FLOWERS: unisexual, perigone absent. MALE FLOWER: stamens 4–5,
connate into a subsessile, rhomboid to hexagonal synandrium, truncate at apex, sulcate laterally, anthers lateral,
common connective thick, fleshy, thecae oblong-ellipsoid,
dehiscing by short, apical, pore-like slit. POLLEN: extruded
in strands, inaperturate, ellipsoid to oblong or nearly spherical, large (mean 79 µm., range 54–99 µm.), exine almost
perfectly psilate to obscurely verruculate and/or sparingly
punctate-foveolate to densely foveolate, rarely coarsely
tuberculate (D. parlatorei). STERILE MALE FLOWERS: composed of a whorl of (3–)4–5(–6), ± flattened, irregularly
globose-ellipsoid, sometimes ± connate staminodes.
35. Dieffenbachia
FEMALE FLOWER: staminodes 4–5 in a whorl, white, clavate
with rounded apices, spreading to erect, surrounding and
longer than gynoecium; ovary stout, subglobose to ovoid,
thickwalled, 1–3-locular, locule walls bulging outwards giving ovary distinctly lobed appearance when plurilocular,
ovules 1 per locule, anatropous, placenta axile to basal,
stylar region inconspicuous, stigma massive, almost as broad
to broader than ovary, 2–3-lobed or subhemispheric (when
unilocular), usually yellow, saturated with oily secretion at
anthesis. BERRY: usually borne in arching infructescence,
berries globose to 2–3-furrowed, stigma remnants persistent,
1–3-seeded, scarlet red to orange. SEED: globose to ovoid,
testa smooth, green to blackish green, embryo large,
endosperm absent. See Plates 35, 114B.
CHROMOSOMES: 2n = 34, 68.
DISTRIBUTION: 30 spp.; tropical and subtropical America,
West Indies: Argentina (Corrientes, Misiones), ?Belize,
?Bolivia, Brazil (Amazonia, Central West, South), Colombia,
Costa Rica, Dominican Republic, Ecuador, El Salvador, French
Guiana, Guatemala, Guyana, Haiti, Honduras, Jamaica, Lesser
Antilles, Mexico, Nicaragua, Panama, Paraguay, Peru, Puerto
Rico, Surinam, Trinidad, Venezuela.
ECOLOGY: tropical and subtropical humid forests, helophytes,
at edges of stream banks, or terrestrial in forest leaf litter.
ETYMOLOGY: named after J. Dieffenbach (1796–1863), head
gardener at the Imperial Palace of Schönbrunn, where Schott
was Director.
TAXONOMIC ACCOUNTS: Engler (1915), Young (1986).
DIEFFENBACHIEAE : DIEFFENBACHIA
153
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L
B
A
H
E
K
D
J
F
G
C
Plate 35. Dieffenbachia. A, habit × 1/4; B, leaf × 1/3; C, inflorescence, nearside half of spathe removed × 2/3; D, detail of spadix showing
sterile zone between male and female zones × 2; E, synandrium × 6; F, female flower × 6; G, gynoecium, transverse section × 6; H, infructescence × 2/3; J, habit, upper part of stem removed × 1/4; K, leaf × 1/2; L, detail of leaf venation × 5. Dieffenbachia seguine cv. Reginae: A,
Cult. Kew 1950–48701; D. seguine: B, Bunting 2026A (K); D. seguine var. viridis: C–G, Cult. Kew 1973–13142 (Kew spirit collection 58927); D.
seguine: H, Croat 65536 (Kew slide collection); D. elegans: J, Cremers 5730 (K); D. paludicola: K–L, Liesner 4006 (K).
154
THE GENERA OF ARACEAE
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C
36. Bognera
Bognera Mayo & Nicolson in Taxon 33: 690 (1984). TYPE:
B. recondita (Madison) Mayo & Nicolson (Ulearum reconditum Madison).
HABIT: evergreen herb with creeping rhizomatous stem,
cataphylls marcescent, persistent and entire, drying reddish-brown. LEAVES: erect, several. PETIOLE:
shortly-sheathed, pilose, weakly geniculate at apex and
base. BLADE: ovate, base rounded, apex acute; primary lateral veins pinnate, ca. 12 per side, glabrous adaxially,
minutely pilose abaxially especially along veins, running
into marginal vein, secondary laterals arcuate and ± parallel to primaries, finer veins reticulate. INFLORESCENCE:
solitary, erect. PEDUNCLE: shorter than petiole, subtended
by 3 cataphylls. SPATHE: erect, broadly ovoid, convolute in
lower two-thirds, not constricted, apiculate, persistent.
SPADIX: subequal to spathe, fertile to apex or most apical
flowers sterile, female zone laxly flowered and entirely
adnate to spathe, separated from male zone by very
sparsely flowered sterile zone, male zone densely flowered.
FLOWERS: unisexual, perigone absent. MALE FLOWER:
3–4-androus, stamens connate into a synandrium, synandria
truncate, irregularly rhombic, somewhat domed, usually
with central slit, common connective very thick, thecae
ellipsoid-oblong, lateral, dehiscing apically by very broad
slit. POLLEN: inaperturate, broadly ellipsoid, large (50–60
µm.), exine scabrate to nearly smooth (psilate). STERILE
MALE FLOWERS: each usually consisting of 4 staminodes,
those of lower flowers ± free and roundish, upper ones
nearly completely connate and irregularly formed, sometimes all 4 connate with a central slit. FEMALE FLOWER:
gynoecia arranged in somewhat distant spirals, ovary
depressed globose, 1-locular, ovule 1, anatropous, funicle
short, placenta basal, stigma sessile, discoid, broad. BERRY:
unknown. SEED: unknown. See Plates 36, 114C.
CHROMOSOMES: 2n = 34 (karyotype resembles that of
Dieffenbachia).
DISTRIBUTION: 1 sp.; Brazil (Amazonas), ?Peru.
ECOLOGY: tropical humid forest (“terra firme”); terrestrial,
creeping in leaf litter on sandy soil.
NOTES: The mature shoot architecture seems to consist of
repeating units of one small cataphyll, one larger cataphyll
and one foliage leaf (T. Ray, pers. comm.).
ETYMOLOGY: Named after Josef Bogner (born 1939).
TAXONOMIC ACCOUNTS: Madison (1980, as Ulearum
reconditum).
C
Tribe Spathicarpeae
Tribe Spathicarpeae Schott, Syn. Aroid. 214 (1856).
Laticifers present, simple, articulated; seasonally dormant,
stem tuberous, hypogeal; primary lateral veins of leaf or leaf
lobes forming single marginal vein (except Spathantheum
and Spathicarpa), higher order venation reticulate; spathe
unconstricted; spadix fertile to apex (except Mangonia); flowers unisexual, perigone absent; male flower a synandrium of
partially or completely connate stamens (sometimes completely free in Gorgonidium); in female flower the gynoecium
surrounded by whorl of free staminodes or by cup-like synandrode, ovules 1 per ovary locule (except Mangonia); embryo
relatively small, axile, endosperm copious.
36. Bognera
C
37. Mangonia
Mangonia Schott in Oesterr. bot. Wochenbl. 7: 77 (1857).
TYPE: M. tweedieana Schott (“twedieana”).
SYNONYMS: Felipponia Hicken in Anales Soc. Ci. Argent.
84: 242 (1917), non Felipponea Brotherus (1912);
Felipponiella Hicken in Darwiniana 2: 30 (1928).
HABIT: seasonally dormant small herbs, tuber depressed-globose, deeply embedded in soil. LEAVES: few to several.
PETIOLE: sheath long. BLADE: linear-elliptic or broadly ovateelliptic to oblong-sagittate; primary lateral veins pinnate, few,
running into margin, higher order venation reticulate. INFLORESCENCE: solitary, appearing before the leaves. PEDUNCLE:
fairly long, mostly subterranean. SPATHE: erect, not constricted, lower part convolute into subcylindric tube, blade
lanceolate to oblong, erect, gaping. SPADIX: subequal to
spathe, sessile, female zone short, densely flowered, male
zone less densely to laxly flowered especially in basal portion,
either contiguous with female or separated by short ± naked
axis, apical third to half of spadix more densely flowered and
covered with sterile male flowers. FLOWERS: unisexual,
perigone absent. MALE FLOWER: 2–5-androus, stamens with
filaments connate, forming stipitate or sessile synandrium,
anthers free, connective inconspicuous, thecae ellipsoid to
globose, dehiscing by a narrow slit or apical pore. STERILE
MALE FLOWERS: synandrode stipitate, consisting of 3–5 subcapitate, basally connate staminodes. POLLEN: inaperturate,
ellipsoid, medium-sized (40 × 25 µm.), exine areolate to subrugulate. FEMALE FLOWER: gynoecium surrounded by whorl
of 3–4 clavate-spathulate staminodes, ovary globose to ovoid,
2–3-locular, ovules 2 per locule, anatropous, funicle short,
placenta axile in upper part of septum, stylar region distinct,
narrower than ovary, stigma 3-lobed or discoid, broader than
style, concave centrally. BERRY: depressed-globose, in dense,
subglobose to shortly cylindric infructescence. SEED: ellipsoid,
somewhat compressed, testa smooth, embryo and endosperm
unknown. See Plates 37, 114D.
CHROMOSOMES: unknown.
SPATHICARPEAE : MANGONIA
155
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B
D
E
G
F
H
C
J
A
Plate 36. Bognera. A, habit × 2/3; B, detail of leaf venation and trichomes on abaxial surface × 15; C, inflorescence, nearside lower half
of spathe removed × 1; D, synandrium, top view × 8; E, synandrium, side view × 8; F, staminode, top view × 8; G, staminode, side view
× 8; H, gynoecium × 8; J, gynoecium, longitudinal section × 8. Bognera recondita: A–B, Bogner 1995 (K); C–J, Bogner 1995 (Kew spirit
collection 57525).
156
THE GENERA OF ARACEAE
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J
F
D
E
Q
G
K
H
N
L
P
A
C
B
M
S
R
Plate 37. Mangonia, A, habit showing inflorescence and petiole base only × 2/3; B, habit × 2/3; C, spadix × 1; D, synandrium, top view ×
15; E, synandrium, side view × 15; F, synandrode × 15; G, gynoecium with associated staminodes × 15; H, gynoecium, longitudinal section ×
15; J, infructescence × 1; K, leaf × 2/3; L, inflorescence × 1; M, spadix × 2; N, synandrium, top view × 15; P, synandrium, side view × 15; Q,
synandrode × 15; R, gynoecium with associated staminodes × 15; S, gynoecium, longitudinal section × 15. Mangonia uruguaya: A, Darwiniana
18: 73, fig. 1,1; B, Darwiniana 18: 74, fig. 2,2; C–H, Felippone 5772 (SI); Felippone SI 297 (K, Kew spirit collection 58120 & SI); J, Darwiniana
18: 74, fig. 2,3 (1973); M. tweedieana: K, Waechter 2347 (K); L–S, Tweedie s.n. (K, LE); Waechter 2347 (K & Kew spirit collection 58090).
SPATHICARPEAE : MANGONIA
157
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37. Mangonia
DISTRIBUTION: 2 spp.; warm temperate South America:–
Brazil (Rio Grande do Sul), Uruguay.
ECOLOGY: subtropical gallery forest; geophytes, stony, well
drained soils, flat areas, slopes near water courses.
NOTES: The first reliable record of M. tweedieana for Brazil
was recently made by Prof. Jorge Waechter (Waechter 2347
[ICN, K!]), who also provided important new information
contained in this generic treatment.
ETYMOLOGY: Latin mango, mangonis (dealer, hence English
monger).
TAXONOMIC ACCOUNTS: Engler (1920a), Herter (1943),
Bogner (1973a).
C
38. Taccarum
Taccarum Brongniart ex Schott in Oesterr. bot. Wochenbl.
7: 221 (1857). TYPE: T. weddellianum Brongniart ex Schott
SYNONYMS: Lysistigma Schott in Bonplandia 10: 222
(1862); Endera Regel in Gartenflora 21: 226 (1872).
HABIT: seasonally dormant herbs, often robust, tuber
depressed-globose. LEAF: solitary. PETIOLE: terete, mottled
and variegated or not, sheath very short. BLADE: juvenile
leaves simply lobed, adult leaves subdracontioid, trifid to trisect, anterior division usually deeply bipinnatifid, often
tripinnatifid in lower pinnae, posterior divisions deeply pedatifid with segments themselves pinnatifid, ultimate lobes
subtriangular to elliptic or lanceolate, acute to acuminate,
broadly decurrent; basal ribs well-developed, primary lateral
veins of ultimate lobes pinnate, running into inconspicuous
marginal vein, higher order venation reticulate. INFLORESCENCE: 1, rarely 2 in each floral sympodium. PEDUNCLE:
usually much shorter than petiole. SPATHE: not constricted,
tube convolute, blade gaping to widely spreading, marcescent
158
THE GENERA OF ARACEAE
38. Taccarum
and later deciduous (T. weddellianum). SPADIX: free or female
zone adnate to spathe, sessile or stipitate, erect, much longer
than, subequal or shorter than spathe, male zone usually contiguous with female, rarely with a few bisexual flowers in
between, fertile to apex. FLOWERS: unisexual, perigone absent.
MALE FLOWER: 3–8-androus, stamens connate, synandrium
very long-stipitate with apical whorl of anthers to short with
anthers near base, stigmatoid apex inconspicuous or distinct
and 4–6-lobed, or very large and dome-shaped, thecae oblong
or broadly ellipsoid, dehiscing by short apical slit or pore.
POLLEN: extruded in strands, inaperturate, ellipsoid to oblong,
large (mean 63 µm., range 49–76 µm.), exine scabrate or verruculate or spinulose-spinose, or smooth (psilate). FEMALE
FLOWER: gynoecium surrounded by whorl of 4–6 free, erect,
filiform, clavate or oblong, often flattened staminodes, or by
urceolate synandrode composed of connate staminodes (T.
caudatum), ovary 3–6(–7)-locular, ovules 1 per locule, anatropous, funicle short, placenta axile, style very long and slender
or very short to ± absent, always narrower than ovary, stigma
thick, capitate or 5–7-lobed, lobes erect or stellate. BERRY:
borne in cylindric infructescence, depressed-globose, slightly
furrowed, stylar region persistent, 3–5-seeded. SEED: ellipsoid,
raphe conspicuous, testa granulate, light brown, embryo
straight, elongate, endosperm copious. See Plates 38, 115A.
CHROMOSOMES: 2n = 34.
DISTRIBUTION: 5 spp.; tropical and subtropical South
America:– N. Argentina (Misiones), Bolivia, Brazil, Paraguay,
Peru.
ECOLOGY: open tropical woodland (cerrado), forests, humid
mountain valleys; geophytes, often in stony soils or between
rocks.
ETYMOLOGY: Malay taka (name for Tacca in the Taccaceae)
and Arum; refers to similarity of the leaf to that of Tacca leontopetaloides.
TAXONOMIC ACCOUNTS: Engler (1920a), Bogner (1989a).
26c Tribes & Genera Acro 17/7/97 17:38 Page 159
B
J
A
L
M
N
D
C
H
E
F
G
K
Plate 38. Taccarum. A, leaf × 6; B, flowering habit, leaf removed × 1/8; C, spadix × 1/2; D, synandrium × 3; E, female flower × 3; F, gynoecium, longitudinal section × 3; G, gynoecium, tranverse section × 3; H, infructescence × 1/2; J, habit × 1/5; K, inflorescence, nearside half of
spathe removed × 1/3; L, synandrium × 3; M, female flower × 3; N, gynoecium, longitudinal section × 3. Taccarum weddellianum: A, Pirani
et al. 1946 (K); B, Cult. Hetterscheid (Kew slide collection); C–G, Bogner 458 (Kew spirit collection 29047.741); H, Harley 20436A (Kew spirit
collection 29047.453); T. warmingii: J, Type drawing (Kew illustration collection); K–N, Cult. Kew 9 April 1890 (K & Kew spirit collection 58086).
SPATHICARPEAE : TACCARUM
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39. Asterostigma
Asterostigma F.E.L. Fischer & C.A. Meyer in Bull. Cl. Phys.Math. Acad. Imp. Sci. Saint Pétersbourg, ser. 2, 3: 148 (1845).
TYPE: A. langsdorffianum F.E.L. Fischer & C.A. Meyer
SYNONYMS: Staurostigma Scheidweiler in Allg.
Gartenzeitung 16: 129 (1848); Andromycia A. Richard in R.
de la Sagra, Hist. Fis. Cuba 11: 282 (1850); Rhopalostigmium
Schott in Oesterr. bot. Zeitschr. 9: 39 (1859); [Rhopalostigma
B.D. Jackson, Index Kew. 2: 713 (1895), orth. var., non R.A.
Philippi (1860)].
HABIT: medium-sized, seasonally dormant herbs, tuber depressed-globose. LEAVES: usually solitary. PETIOLE: smooth,
maculate, sheath very short. BLADE: usually pinnatisect, rarely
entire, lobes oblong-lanceolate, acute to acuminate; primary
lateral veins of ultimate lobes pinnate, running into marginal
vein, higher order venation reticulate. INFLORESCENCE: 1–3
in each floral sympodium, appearing with or before leaves,
cataphylls often beautifully variegated. PEDUNCLE: rather
long, similar to petiole. SPATHE: erect, hardly to not constricted, slender, persistent, lower part convolute into
narrowly cylindric tube, blade gaping to widely expanded at
anthesis. SPADIX: female zone free or partly adnate to spathe,
laxly flowered, contiguous with male zone, male zone longer,
fertile to apex. FLOWERS: unisexual, perigone absent. MALE
FLOWER: synandrium 3–4-androus, surrounding and concrescent with pistillode, subhexagonal to rounded, sometimes
very shallow, umbonate at apex, shortly stipitate or sessile,
thecae subglobose, distant, almost pendent from upper margin of synandrium, dehiscing by transversely elongated pore.
POLLEN: inaperturate, ellipsoid to ellipsoid-oblong, mediumsized (mean 36 µm., range 35–38 µm.), virtually psilate or
coarsely verrucate. FEMALE FLOWER: gynoecium surrounded
by cup-like synandrode, or by whorl of 3–5 short, somewhat thickened, subcuneate, truncate, often irregularly
connate staminodes, ovary pear-shaped to depressed-globose, 3–5-locular, ovules 1 per locule, anatropous, funicle
39. Asterostigma
160
THE GENERA OF ARACEAE
short, placenta axile at base of septum, stylar region distinct,
stigma usually deeply and stellately 3–5-lobed with each lobe
itself lobed, or 2–3-lobed with oblong, entire lobes. BERRY:
subglobose to depressed-globose, deeply 4–5-sulcate, pale to
whitish green. SEED: oblong to ellipsoid, with swollen arillike funicle, testa nearly smooth, embryo axile, elongate,
endosperm copious. See Plates 39, 115B.
CHROMOSOMES: 2n = 34.
DISTRIBUTION: ca. 7 spp.; tropical and subtropical South
America:– Bolivia, Brazil (Central, Northeast, Southeast,
South), Ecuador, Peru.
ECOLOGY: tropical and subtropical humid forests; geophytes, forest floor.
NOTES: Engler (1920a) recognized 2 sections: sect. Asterostigma, sect. Rhopalostigma.
ETYMOLOGY: Greek astêr (star) and stigma (a mark), refers
to the star-shaped stigmas.
TAXONOMIC ACCOUNTS: Engler (1920a), Bogner (1969),
Bogner (in press).
40. Gorgonidium
Gorgonidium Schott in Ann. Mus. Bot. Lugduno-Batavum 1:
282 (1864). TYPE: G. mirabile Schott
HABIT: seasonally dormant herbs, tuber depressed globose.
LEAF: solitary. PETIOLE: terete, sheath short. BLADE: pinnatifid, pinnatisect or bipinnatifid, pinnae (9–)11–14, elliptic, entire
or pinnatifid (with all intermediates), acute, upper lobes decurrent, lower ones sessile to shortly stalked; primary lateral veins
of ultimate lobes pinnate, running into margin, higher order
venation reticulate. INFLORESCENCE: 1(–2) per floral sympodium, appearing before leaf. PEDUNCLE: much shorter than
petiole. SPATHE: erect or slightly fornicate, boat-shaped, very
shortly convolute at base, not constricted, purple, persistent at
least in lower part. SPADIX: sessile or stipitate (G. mirabile),
fertile to apex, female zone contiguous with and much shorter
than male zone. FLOWERS: unisexual, perigone absent. MALE
FLOWER: 3–7-androus, stamens free or connate to different
degrees into a synandrium, connective slender, sometimes
stipe-like between thecae (G. mirabile), otherwise inconspicuous, thecae globular, sometimes remote from one another,
dehiscing by apical pore or slit, pistillode present or absent, if
present composed of 3–4 stylodia with slightly lobed or discoid-capitate apices (stigmatoids). POLLEN: inaperturate,
ellipsoid, medium-sized (mean 34 µm, range 27–42 µm.), exine
verrucose (G. mirabile) to retiverruculate, sometimes verrucae
irregularly formed and flattened (G. vargasii). FEMALE FLOWERS: gynoecium surrounded by whorl of 6–8 filiform or
subclavate staminodes, ovary subglobular to broadly ovoid,
(2–)4–5(–7)-locular, ovules 1 per locule, orthotropous, ovoid,
funicle half as long as ovule, placenta axile at base of septum,
stylar region short to long, stigma 4–5-lobed or subcapitate.
BERRY: globular to depressed-globular, blackish-purple to
purple, sometimes upper surface somewhat warty (G. vargasii), stigma and style remnants persistent. SEED: ovoid,
globular to ellipsoid, testa brownish, smooth to rough, embryo
elongate, endosperm copious. See Plates 40, 115C.
CHROMOSOMES: 2n = 34.
DISTRIBUTION: 3 spp.; Western and Andean South
America:– N. Argentina, Bolivia, Peru.
ECOLOGY: tropical and subtropical forest or open places,
between 900–3000m; geophytes, stony ground.
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B
Q
J
A
D
G
M
R
H
F
L
C
K
E
S
P
N
Plate 39. Asterostigma. A, leaf × 1/2; B, detail of leaf venation × 5; C, base of plant × 1/2; D, juvenile infructescence enclosed by persistent spathe × 1/2; E, spadix × 2; F, female flower × 10; G, synandrium × 10; H, gynoecium, longitudinal section × 15; J, young plant × 2/3;
K, spadix × 2; L, female flower × 10; M, synandrium × 10; N, female flower × 10; P, gynoecium, longitudinal section × 15; Q, infructescence
× 1; R, leaf × 1/2; S, base of plant × 1/2. Asterostigma cryptostylum: A–H, Bogner 1237 (K & Kew spirit collection 48202); A. riedelianum:
J–P, Harley et al. 18565 (K & Kew spirit collection 39166, 46592, 47693 & Kew slide collection); A. integrifolium: Q–S, Rawlins 204 (K).
SPATHICARPEAE : ASTEROSTIGMA
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K
L
A
H
G
D
J
F
E
B
C
Plate 40. Gorgonidium. A, vegetative habit × 1/5; B, flowering habit, tuber longitudinally split; C, spadix × 2; D, synandrium × 8; E, female
flower × 8; F, gynoecium, longitudinal section × 8; G, gynoecium, transverse section × 8; H, leaf × 2/3; J, infructescence × 2/3; K, synandrium × 3; L, female flower × 3; Gorgonidium vermicidum: A, Bot. Jahrb. Syst. 109:550, fig. 23 (1988); B, Araque & Barkley s.n. (K); Aichinger
2 (Kew slide collection); C–G, Bogner 101(Kew spirit collection 45269); G. vargasii : H, Brunel 557 (K); J, Vargas s.n. (Kew spirit collection
49725); G. mirabile : K–L, Nicolson 3390 (K & Kew spirit collection 58918).
162
THE GENERA OF ARACEAE
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40. Gorgonidium
ETYMOLOGY: Greek Gorgo (the Grim One), -ides (descendant) and -ion (diminutive); the name alludes to the filiform
staminodia and stamens in G. mirabile, the appearance of
which recalls mythic Gorgo, whose hair was a mass of
writhing serpents.
TAXONOMIC ACCOUNTS: Bogner & Nicolson (1988).
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41. Synandrospadix
Synandrospadix Engler in Bot. Jahrb. 4: 61 (1883). TYPE:
S. vermitoxicus (Grisebach) Engler (Asterostigma vermitoxicum Grisebach).
SYNONYMS: Lilloa Spegazzini, Pl. Nov. Crit. Argentina 3:
10 (1897); [Synandriospadix Engler in Engler, Pflanzenreich
73 (IV.23F): 49 (1920), orth. var.].
HABIT: seasonally dormant herb, tuber subglobose. LEAVES:
several. PETIOLE: fairly long, with darker longitudinal striations, sheath long. BLADE: ovate-cordate to -emarginate,
somewhat glaucous; primary lateral veins pinnate, running
into inconspicuous marginal vein, higher order venation
reticulate. INFLORESCENCE: 1, rarely 2 in each floral sympodium, usually appearing with leaves. PEDUNCLE: short.
SPATHE: ovate-lanceolate, boat-shaped, unconstricted, persistent, convolute at base, gaping above, light green outside
with dark longitudinal lines, inside purple and roughened.
SPADIX: much shorter than spathe, subcylindric, obtuse,
female zone partly or completely adnate to spathe, ± laxly
flowered, separated from male zone by a few bisexual or
sterile flowers, male zone longer, fertile to apex. FLOWERS:
unisexual, perigone absent. MALE FLOWER: synandrium
4–5-androus, long-stipitate, stipe elongate-conoid, whorl of
anthers apical or shortly overtopped by central pistillode,
thecae oblong-ellipsoid, dehiscing by longitudinal slit.
POLLEN: purple to pinkish, inaperturate, spherical to subspheroidal, medium-sized (mean 49 µm.), exine spinose.
BISEXUAL FLOWERS: as for female but with whorl of 4–5
free stamens with flattened elongate-triangular filaments and
41. Synandrospadix
thecae dehiscing as above. FEMALE FLOWER: gynoecium
surrounded by 3–5 free, elongate-triangular, flattened, acute
staminodes, ovary ovoid-globose, 3–5-locular, ovules 1 per
locule, orthotropous, funicle distinct, placenta axile-basal,
stylar region attenuate, stigma discoid-subcapitate, slightly
3–5-lobed. BERRY: ± subglobose, 3–5-furrowed, 3–5-seeded,
style persistent. SEED: rather large, ovoid to obnapiform,
testa ± rough, embryo elongate, straight, endosperm copious.
See Plates 41, 115D.
CHROMOSOMES: 2n = 34.
DISTRIBUTION: 1 sp.; N. Argentina, Bolivia, Paraguay, Peru.
ECOLOGY: subtropical dry thorn forest; geophytes in clearings or on stony ground in shade.
ETYMOLOGY: Greek syn (together), anêr, andros (man)
and spadix (spadix).
TAXONOMIC ACCOUNTS: Engler (1920a), Crisci (1971),
Croat & Mount (1988).
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42. Gearum
Gearum N.E.Brown in J. Bot. 20: 196–197 (1882). TYPE: G.
brasiliense N.E.Brown
HABIT: seasonally dormant, tuberous herbs with aromatic
exudate when cut. LEAF: solitary. PETIOLE: sheath distinct,
about half length of petiole. BLADE: subpalmatifid to pedatisect, lobes or segments 5–9; primary lateral veins of each
lobe forming submarginal collective vein on each side,
higher order venation reticulate. INFLORESCENCE: solitary.
PEDUNCLE: very short, much shorter than petiole.
SPATHE: erect, slightly constricted, purplish, tube subcylindric, convolute, blade erect, gaping, oblong, cuspidate.
SPADIX: sessile, shorter than spathe, fertile to apex, female
zone shorter than male and separated from it by a sterile
zone of synandrodes. FLOWERS: unisexual, perigone
absent. MALE FLOWER: 4-androus, synandrium very shallow, subrhombic, truncate, subpeltate or flat and not
subpeltate, thecae ± remote, situated near margin of synan-
SPATHICARPEAE : GEARUM
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A
E
D
F
G
H
J
C
K
B
Plate 41. Synandrospadix. A, habit × 1/4; B, juvenile plant × 1/2; C, leaf × 2/3; D, inflorescence × 2/3; E, spadix × 1; F, synandrium
× 6; G, bisexual flower × 6; H, female flower × 6; J, gynoecium, longitudinal section × 6; K, infructescence × 1/2. Synandrospadix vermitoxicus:
A, 184/10 (Kew slide collection); B, Cult. Kew 9 October 1891 (K); C, Araque & Barkley 440 (K); D–F, H–J, Bogner s.n. (Kew spirit collection 56099); G, Burkart et al. 30412 (K); K, Badcock 815 (K).
164
THE GENERA OF ARACEAE
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42. Gearum
drium, globose to oblong-ellipsoid, dehiscing by apical
pore or occasionally by an oblique slit. POLLEN: ellipsoid,
inaperturate, large (mean 56µm, range 52–60 µm), exine
smooth (psilate) to scabrous-granulate. STERILE MALE
FLOWERS: composed of irregularly elongated, shallow,
truncate synandrodes. FEMALE FLOWER: densely crowded,
gynoecium surrounded by usually 4 staminodes, staminodes laterally compressed, thick, rounded to obovoid or
subtrapezoid, ovary subglobose, 3–4-locular, ovules 1 per
locule, orthotropous, rather elongate, placenta axile at base
of septum, stigma subsessile, ± discoid, slightly (3–)4-lobed.
BERRY: unknown. SEED: unknown. See Plate 42.
CHROMOSOMES: unknown.
DISTRIBUTION: ?2 spp.; Brazil (Central–West).
ECOLOGY: tropical open herbaceous vegetation (cerrado , in
campo limpo); geophytes in low-lying sites prone to periodic
flooding.
ETYMOLOGY: Greek gê (earth) and Arum.
TAXONOMIC ACCOUNTS: Engler (1920a), Bogner &
Nicolson (1988), Mayo, Bogner & Boyce (1994).
H
D
F
B
C
G
A
E
Plate 42. Gearum. A, leaf × 1/3; B, inflorescence × 1/3; C, spadix × 2/3; D, synandrium, top view × 8; E, synandrium, side view × 8; F,
gynoecium with staminode, side view × 8; G, gynoecium, longitudinal section × 8. H, leaf × 1/3. Gearum sp .: A–G Araujo Dias 41 (HRB &
Kew spirit collection 57663); Gearum brasiliense : H from Hatschbach 56028 (K).
SPATHICARPEAE: GEARUM
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43. Spathantheum
Spathantheum Schott in Bonplandia 7: 164 (1859). TYPE:
S. orbignyanum Schott
SYNONYM: Gamochlamys J.G. Baker in Saunders Refug.
Bot. 5: t. 346 (1873).
HABIT: medium-sized, seasonally dormant herbs, tuber depressed-globose, sometimes large. LEAVES: solitary.
PETIOLE: sheath very short. BLADE: outline ovate to ovatecordate, entire or pinnatifid; primary lateral veins pinnate,
running into margin, higher order venation reticulate.
INFLORESCENCE: usually 1, rarely 2 in each floral sympodium, flowering before leaf. PEDUNCLE: short (S.
intermedium) to long (S. orbignyanum), slender. SPATHE:
oblong-elliptic, boat-shaped, not constricted, cuspidate, at
first convolute basally, then widely gaping at anthesis, green
or purple (S. intermedium), entirely persistent. SPADIX:
entirely adnate to spathe (S. orbignyanum) or male part free
(S. intermedium), slightly shorter than spathe, densely flowered, either female zone basal, contiguous with longer male
zone and spadix fertile to apex (S. inter medium, S.
orbignyanum), or female and male zones sometimes separated by a zone of mixed male and female flowers (S.
orbignyanum). FLOWERS: unisexual, perigone absent.
MALE FLOWER: 4–7-androus, stamens either connate into
a long-stipitate, apically convex, peltate and shallowly 5–7lobed (stigmatoid) synandrium with anthers almost pendent
from thickened common connective, or filaments connate,
anthers free and stigmatoids elongated, overtopping anthers
(S. intermedium), thecae linear-oblong and dehiscing by
longitudinal slit (S. orbignyanum) or subglobose and
dehiscing by apical pore (S. intermedium). POLLEN: inaperturate, ellipsoid-oblong, large (mean 54 µm.), exine nearly
psilate or shallowly uneven. FEMALE FLOWER: gynoecium
surrounded by whorl of 5–8 terete-clavate, short staminodes, ovary ovoid-ellipsoid, 5–8-locular, ovules 1 per locule,
43. Spathantheum
166
THE GENERA OF ARACEAE
suborthotropous, funicle distinct, placenta axile at base of
septum, stylar region elongate-attenuate, stigma stellate,
6–8-lobed, lobes subtriangular. BERRY: subglobose to
depressed-globose, 5–8-seeded. SEED: shortly ovoid to ±
ellipsoid, testa ± smooth to slightly roughened, embryo
elongate, endosperm copious. See Plates 43, 116A.
CHROMOSOMES: 2n = 34.
DISTRIBUTION: 2 spp.; Andean South America:– N. Argentina,
Bolivia, Peru.
ECOLOGY: tropical and subtropical uplands, mountain grasslands, up to 2400m; geophytes on stony ground in shade, in
deposits of humus on rocks.
ETYMOLOGY: Greek spathê, anthos (flower) and -eum (possessing); refers to the fusion of the spadix to the spathe.
TAXONOMIC ACCOUNTS: Engler (1920a), Crisci (1971),
Bogner (in press).
44. Spathicarpa
Spathicarpa W.J. Hooker in Bot. Misc. 2: 146 (1831). TYPE:
S. hastifolia W.J. Hooker
SYNONYMS: [Spaticarpa Schott in Oesterr. bot. Zeitschr.
15: 34 (1865), orth. var.]; Aropsis Rojas Acosta in Bull. Acad.
Int. Géogr. Bot. 28: 158 (1918).
HABIT: small, seasonally dormant, sometimes evergreen
herbs, tuber subterranean, rhizomatous, shortly oblong, horizontal. LEAVES: several. PETIOLE: slender, sheath often rather
long. BLADE: narrowly elliptic, oblong, ovate-emarginate,
ovate-cordate, cordate, cordate-sagittate, auriculate-hastate
or strongly hastate to subtrisect; basal ribs short when present, primary lateral veins pinnate or mostly arising at petiole
insertion, arcuate and running into margin or forming an
irregular, submarginal collective vein, higher order venation
reticulate. INFLORESCENCE: solitary, appearing with leaves.
PEDUNCLE: relatively long, slender. SPATHE: not constricted,
44. Spathicarpa
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J
E
F
G
H
D
K
L
M
N
P
B
C
A
Plate 43. Spathantheum. A, flowering habit × 2/3; B, juvenile leaf × 2/3; C, mature leaf × 2/3; D, inflorescence, nearside half of spathe
removed × 2/3; E, synandrium × 4; F, female flower × 4; G, gynoecium, longitudinal section × 4; H, gynoecium, transverse section × 6; J,
infructescence × 2/3; K, inflorescence, nearside half of spathe removed × 2/3; L, synandrium × 4; M, gynoecium with associated staminodes
(= female flower) × 4; N, gynoecium, longitudinal section × 4; P, gynoecium, transverse section × 6. Spathantheum orbignyanum: A, Bang
1626 (K), Rauh 26024 (Kew spirit collection 37322); B, Bogner 900 (K); C, Cult. Kew 1883 (K); D–H, Rauh 26024 (Kew spirit collection 37322);
Bogner 900 (K & Kew spirit collection 37369); S. intermedium: K–P, Munn 148 (Kew spirit collection 29047.761).
SPATHICARPEAE : SPATHANTHEUM
167
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B
C
E
K
G
D
A
F
H
J
Plate 44. Spathicarpa. A, habit × 2/3; B, synandrium and gynoecium with associated staminodes (= male and female flowers) × 10; C, gynoecium, longitudinal section × 16; D, leaf × 2/3; E, habit × 2/3; F, inflorescence × 2; G, detail of spadix × 6; H, synandrium and gynoecium with
associated staminodes (= male and female flowers) × 10; J, gynoecium, longitudinal section × 16; K, infructescence, nearside half of spathe
removed × 1. Spathicarpa burchelliana: A, Burchell 8335(K); Gardner 2447 (K); B–C, Cult. Kew 1981–388, Cristobal & Krapovickas s.n. (Kew
spirit collection 45662); S. lanceolata: D, Balansa 579 (K); S. hastifolia (S. cf. gardneri ): E–K, Tressens et al. 1569 (K); Tressens et al. 3471 (K).
168
THE GENERA OF ARACEAE
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oblong-lanceolate to narrowly elliptic or oblanceolate, acuminate, fully expanded to subrevolute at anthesis, later closing,
persistent, green. SPADIX: entirely adnate to spathe, recurved
at anthesis, fertile to apex, ± laxly flowered, female flowers
forming 2 outer longitudinal rows, enclosing 2 rows of male
flowers, all in parallel. FLOWERS: unisexual, perigone absent.
MALE FLOWER: 3-4-androus, stamens connate, synandrium
stipitate, apex formed by nectariferous, usually shallowly
lobed stigmatoid-connective, anthers short, partly covered
and overtopped by stigmatoid-connective, thecae 6-8, broadly
ellipsoid, lateral, dehiscing by subapical pore. POLLEN:
extruded in strands, inaperturate, ellipsoid-oblong to -elongate, medium-sized (mean 48 µm., range 45-51 µm.), exine
almost perfectly psilate. FEMALE FLOWER: gynoecium partially surrounded on one side by 3 small, very shortly stipitate,
discoid-umbonate, green staminodes, ovary oblong-ovoid,
1-locular, ovule 1, orthotropous, funicle very short to ±
absent, placenta basal, stylar region attenuate, cylindricconoid, stigma discoid-subcapitate. BERRY: ovoid to ellipsoid,
acute-attenuate, green. SEED: ovoid-obnapiform, strophiolate,
testa smooth to ± rough, brownish to green, embryo axile,
elongate, endosperm copious. See Plates 44, 116B.
CHROMOSOMES: 2n = 34.
DISTRIBUTION: ca. 5 spp.; tropical and subtropical South
America:– N. Argentina, Bolivia, Brazil (Northeast, Central
West, Southeast, South), Paraguay, Uruguay.
ECOLOGY: tropical dry forest, humid and marshy forest,
seasonally wet places; geophytes; in dry forest areas the
plant has a dormant period and starts growth at the beginning of the rainy season.
ETYMOLOGY: Greek spathê (spathe) and karpos (fruit);
refers to the fusion of spathe and spadix (in fruit).
TAXONOMIC ACCOUNTS: Engler (1920a), Crisci (1971),
Uhlarz (1983), Croat & Mount (1988).
C
HABIT: evergreen herbs, small to gigantic, stem repent to
rhizomatous, climbing, arborescent or plant rosulate and
acaulescent, internodes usually long, often short to very
short, intravaginal squamules present, sometimes producing
flagelliform shoots. LEAVES: numerous, small to gigantic,
prophylls of mature stems caducous, marcescent and deciduous or persistent and membranaceous or decomposing to
net-fibrous remains. PETIOLE: sometimes warty or covered
with scale-like processes, sometimes swollen, rarely geniculate apically, sheath long and slilghtly ligulate in monopodial
leaves of all subgenera and in sympodial leaves of subgen.
Pteromischum, otherwise very short and inconspicuous
except when subtending inflorescences. BLADE: very variously shaped; simple and linear, cordate, sagittate or hastate,
or trifid, trisect, pinnatifid, bipinnatifid, rarely pedatisect,
resin canals linear, short to long, obscured to very distinct on
abaxial surface; basal ribs sometimes well-developed, primary lateral veins pinnate, rarely pedate, running into
marginal vein, secondary lateral and higher order venation
parallel-pinnate, sometimes tertiaries and higher order veins
transversely reticulate between secondaries, sometimes all
veins slender with no distinct primary laterals. FLOWERING
BRANCHES: sympodial articles of three main patterns:– subgen. Pteromischum: prophyll, many foliage leaves, 1–2(–3)
inflorescences; subgen. Philodendron: prophyll, following
internode suppressed, 1 foliage leaf, 1–11 inflorescences,
internode to prophyll of continuation shoot elongated; subgen. Meconostigma: prophyll, following internode developed
or very short, 1 foliage leaf, 1(–2) inflorescences, internode
to prophyll of continuation shoot suppressed. INFLORESCENCE: 1–11 in each floral sympodium, secreting resin at
anthesis, either from spathe or from spadix, rarely from both.
PEDUNCLE: usually much shorter than petiole. SPATHE:
erect, entirely persistent, deciduous only at ripening of fruit
(caducous after anthesis in P. surinamense), fairly thick,
Tribe Philodendreae
Tribe Philodendreae Schott, Syn. Aroid. 71 (1856).
Laticifers present, simple, articulated, resin canals present in
roots, stems, leaves and inflorescences, sclerotic hypodermis
present in roots; diminutive to gigantic, climbing hemiepiphytes, epiphytes or terrestrial, stem usually epigeal,
intravaginal squamules present; petiole only rarely geniculate
apically; primary lateral veins pinnate (very rarely pedate)
forming 1 marginal vein, higher order venation parallel-pinnate; spathe persisting until fruit maturity, then deciduous at
base; flowers unisexual, perigone absent; anther lacking cell
wall thickenings in endothecium (except P. goeldii, P. lealcostae); endosperm copious.
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45. Philodendron
Philodendron Schott in Wiener Z. Kunst 1829 (3): 780
(1829), nom. et orth. cons. (‘Philodendrum’). LECTOTYPE: P.
grandifolium (Jacq.) Schott (see Britton & Wilson 1923).
SYNONYMS: Philodendrum Schott in Wiener Z. Kunst
1929 (3): 780 (1829), orth. rej.; Arosma Rafinesque, Fl. Tell. 3:
66 (1837, “1836”); Telipodus Rafinesque, Fl. Tell. 3: 66 (1837,
“1836”); Thaumatophyllum Schott in Bonplandia 7: 31 (1859);
Elopium Schott in Oesterr. bot. Zeitschr. 15: 34 (1865); Baursea
Post & O. Kuntze, Lexicon Gen. Phanerog. 62 (1903).
45. Philodendron
PHILODENDREAE : PHILODENDRON
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E
D
C
A
K
B
G
F
J
H
Plate 45 (i). Philodendron. A, leaf × 1/2; B, leaf × 1/2; C, leaf × 1/2; D, leaf × 1/2; E, leaf × 1/2; F, leaf × 1/2; G, leaf × 1/2; H, leaf × 1/2;
J, leaf × 1/2; K, leaf × 1/2. Philodendron callosum: A, Granville et al. 10487 (K); P. crassinervium : B; Hatschbach 45979 (K); P. fibrillosum:
C, Plowman et al. 11406 (K); P. calatheifolium: D, Bunting 11659 (K); P. heterophyllum: E, Whitmore 748 (K); P. blanchetianum: F, Storr
13 (K); P. grazielae: G, Dodson 2718 (K); P. frits-wentii: H, Madison 4175 (K); P. aromaticum: J, Croat 68423 (K); P. sp. cf. verrucosum: K,
André 2629 (K).
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B
C
A
D
E
Plate 45 (ii). Philodendron. A, leaf × 1/2; B, leaf × 1/2; C, leaf × 1/3; D, leaf × 1/3; E, leaf × 1/6. Philodendron bipennifolium: A, Engler
237 (K); P. anisotomum: B, Heyde & Lux 4283 (K); P. goeldii: C, Stevenson 829 (K); P. angustisectum: D, Cult. Kew 1984–1076; E, P. bipinnatifidum: Mayo et al. 574 (K).
PHILODENDREAE : PHILODENDRON
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A
C
B
D
E
F
Plate 45 (iii). Philodendron. A, habit × 1/6; B, leaf × 1/12; C, habit × 1/12; D, habit × 1/3; E, detail of lower stem showing intravaginal
squamules × 1/2; F, habit × 1/12. Philodendron insigne: A, Cult. Kew. 1980–2229; P. verrucosum : B, Boyce s.n. (Kew slide collection); P. bipinnatifidum: C, Cult. Kew 1983–2024; P. scandens: D, Cult. Kew 1953–43201; P. uliginosum: E, Kew Bull. 46(4): 601–681, f.3, A (1991); P.
melinonii: F, Cult. Kew 1970–84.
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B
A
D
C
Plate 45 (iv). Philodendron. A, inflorescence and associated leaf × 1/2; B, infructescences and associated stem and petiole bases × 1/2; C,
floral sympodium and associated stem and petiole base × 1/2; D, inflorescence and associated petiole base × 1/2. Philodendron rigidifolium:
A, Sugden 585 (K); P. leal-costae: B, Harley et al. 19428 (Kew slide collection); P. verrucosum: C, Knapp 4959 (K); McPherson 9033 (K); P.
bipinnatifidum: D, Boyce s.n. (Kew slide collection).
PHILODENDREAE : PHILODENDRON
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B
L
G
C
N
M
D
E
H
K
J
Q
DD
A
F
R
S
T
EE
AA
V
X
W
FF
CC
BB
P
Z
Y
U
Plate 45 (v). Philodendron. A, spadix × 1; B, stamen × 10; C, gynoecium × 10; D, gynoecium, longitudinal section × 10; E, gynoecium,
transverse section × 10; F, spadix × 1; G, stamens × 10; H, gynoecium × 10; J, gynoecium, longitudinal section × 10; K, spadix × 1; L, stamen
× 10; M, gynoecium × 10; N, gynoecium, longitudinal section × 10; P, spadix × 1; Q, stamen × 10; R, gynoecium × 10; S, gynoecium, longitudinal section × 10; T, gynoecium, transverse section × 10; U, spadix × 1; V, stamen × 10; W, gynoecium × 10; X, gynoecium, longitudinal
section × 10; Y, gynoecium, transverse section × 10; Z, spadix × 2/3; AA, gynoecium × 5; BB, gynoecium, longitudinal section × 5; CC, spadix
× 2/3; DD, stamen × 8; EE, gynoecium × 8; FF, gynoecium, longitudinal section × 8. Philodendron bipennifolium: A–E, Mayo 599 (Kew spirit collection 46286); P. melinonii: F–J, Evemy & Burgess 161 (Kew spirit collection 29047.428); P. blanchetianum: K–N, Storr 13 (Kew spirit collection
48471); P. eximium: P–T, Boyce s.n. (Kew spirit collection 51441); P. inaequilaterum: U–Y, Cult. Kew 1964–39505 (Kew spirit collection 49977);
P. goeldii: Z–BB, Bogner 233 (Kew spirit collection 29047.740); P. bipinnatifidum: CC–FF, Boyce s.n. (Kew spirit collection 29047.785).
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sometimes (subgen. Meconostigma) extremely thick, usually
constricted between tube and blade, tube convolute, cylindric to ventricose, often coloured purple or red within, blade
usually boat-shaped, widely gaping at anthesis, later closing,
usually white within, rarely red. SPADIX: sessile to stipitate,
female zone free, rarely basally adnate to spathe, usually
shorter than male zone and separated from it by intermediate sterile zone of staminodial flowers, intermediate sterile
zone cylindric or constricted or ellipsoid and thicker than
male zone, usually shorter than male zone, sometimes longer
(subgen. Meconostigma), a terminal staminodial appendix
sometimes also present. FLOWERS: unisexual, perigone
absent. MALE FLOWER: 2–6-androus, stamens free, prismatic
to obpyramidal, sometimes very elongated and slender (subgen. Meconostigma), anthers sessile to subsessile, connective
thick, apically truncate, overtopping thecae, thecae ellipsoid
to oblong, dehiscing by short lateral slit or by subapical pore,
endothecial thickenings lacking (except P. goeldii, P. lealcostae). POLLEN: extruded in strands or mixed with resin
secretion or exuded in amorphous masses, inaperturate, ellipsoid to oblong or occasionally elongate, medium-sized (mean
40 µm., range 28–54 µm.), mostly perfectly psilate, sometimes
from minutely verruculate, scabrate or fossulate to clearly
punctate, subfossulate, subfoveolate or subverrucate, rarely
densely and coarsely verrucate (P. leal-costae). STERILE MALE
FLOWERS: staminodes usually prismatic, truncate, sometimes
clavate, often somewhat similar to stamens. FEMALE
FLOWER: gynoecium ovoid, subcylindric, cylindric or
obovoid, ovary (2–)4–8(–47)-locular, ovules 1–50 or more
per locule, usually hemiorthotropous, rarely hemianatropous
to nearly anatropous, funicle long to very short, placenta
axile to basal, stylar region usually as broad as ovary, sometimes slightly broader, sometimes attenuate, rarely elongate,
lobed in subgen. Meconostigma, stigma sometimes also lobed
or discoid-hemispheric, often as broad as style. BERRY: subcylindric to obovoid, 1–many-seeded, white, whitishtranslucent, red or orange-red. SEED: tiny to fairly large,
ovoid-oblong to ellipsoid, rarely arillate (in P. goeldii funicle
thick, swollen, much larger than seed itself), testa thick,
costate, rarely sarcotestate, embryo axile, straight, elongate,
endosperm copious. See Plates 45i–v, 116C.
CHROMOSOMES: 2n = 28, 30, 32, 34, 36 (26, 48).
DISTRIBUTION: over 500 spp.; tropical and southern subtropical America, West Indies:– Argentina, Belize, Bolivia,
Brazil, Colombia, Costa Rica, Cuba, Dominican Republic,
Ecuador, El Salvador, French Guiana, Guatemala, Guyana,
Haiti, Honduras, Jamaica, Lesser Antilles, Mexico, Nicaragua,
Panama, Paraguay, Peru, Puerto Rico, Surinam, Trinidad &
Tobago, Uruguay, Venezuela.
ECOLOGY: usually tropical humid forest, more rarely in open
woodland, swamps, streamsides; climbing hemiepiphytes,
rosulate acaulescent epiphytes, rhizomatous terrestrials, lithophytes (also on cliffs), helophytes, mostly shade-loving,
sometimes arborescent.
NOTES: Mayo (1986b, 1989b, 1990a, 1991) recognized 3 subgenera: subgen. Philodendron, subgen. Pteromischum
(partially revised by Grayum 1996), subgen. Meconostigma
(revised by Mayo 1991).
ETYMOLOGY: Greek philos (fond of) and dendron (tree);
refers to the predominantly epiphytic or hemiepiphytic habit.
TAXONOMIC ACCOUNTS: Krause (1913), Bunting (1968,
1977, 1980, 1984), Mayo (1986b, 1989a, b, 1990a, 1991),
Grayum (1992b, 1996), Croat & Grayum (1994), Sakuragui
(1994), Nadruz Coelho (1995).
Tribe Homalomeneae
C
Tribe Homalomeneae (Schott) M. Hotta in Mem. Fac. Sci.
Kyoto Univ., ser. Biol. 4: 89 (1970).
Laticifers present, simple, articulated, resin canals present in
roots, stems and leaves, sclerotic hypodermis present in
roots; terrestrial or rheophytic, diminutive to robust, stem
usually epigeal; petiole geniculum absent (very rarely present in Homalomena); primary lateral veins pinnate forming
1 marginal vein, higher order venation parallel-pinnate;
spathe often boat-shaped, constricted or unconstricted, persistent, closing after anthesis; flowers unisexual, perigone
absent; anther with cell wall thickenings in endothecium;
endosperm copious.
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46. Furtadoa
Furtadoa M. Hotta in Acta Phytotax. Geobot. 32: 142 (1981).
TYPE: F. sumatrensis M. Hotta
HABIT: small evergreen herbs, stem repent. LEAVES: several to
many. PETIOLE: sheath to half as long as petiole or more.
BLADE: elliptic; primary lateral veins pinnate, running into
margin, higher order venation parallel-pinnate. INFLORESCENCE: 1–3 in each floral sympodium. PEDUNCLE: shorter
than or subequal to petiole. SPATHE: green, ellipsoid, not constricted, boat-shaped, persistent. SPADIX: subcylindric, tapering
apically, female zone a third to nearly half spadix length, male
zone contiguous with female. FLOWERS: unisexual, perigone
absent; each male and female flower with a stamen or staminode situated basally to pistillode or gynoecium respectively.
MALE FLOWER: consisting of a single free stamen overtopped
by single flask-shaped pistillode with subglobose stigmatoid
apex, pistillodes absent from apical flowers, stamen apex truncate, connective thick, thecae ovoid, dehiscing by short,
longitudinal slit. POLLEN: inaperturate, ellipsoid-oblong, small
(mean 17 µm.), exine virtually psilate. FEMALE FLOWER: consisting of gynoecium with single, shorter, obovoid, apically
truncate staminode, lowermost flowers sometimes apparently
with more than one staminode, gynoecium ovoid, ovary 1-
46. Furtadoa
HOMALOMENEAE : FURTADOA
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C
D
F
E
B
L
K
N
M
J
H
A
G
Plate 46. Furtadoa. A, habit × 2/3; B, spadix × 3; C, stamens with associated pistillodes, × 15; D, stamen and associated pistillode, top view
× 15; E, gynoecia with associated staminodes, × 15; F, gynoecium, longitudinal section × 15; G, habit × 2/3; H, detail of leaf tip tubule × 8;
J, spadix × 3; K, stamen with associated pistillode, gynoecium in longitudinal section × 15; L, stamen and associated pistillode, top view ×
15; M, gynoecia with associated staminodes, upper gynoecium in longitudinal section × 15; N, gynoecium with associated staminode, top
view × 15. Furtadoa mixta: A, Nur 11091 (K); B–F, Hay 9131 (Kew spirit collection 58934); F. sumatrensis: G–H, Hotta s.n. (K); J, Bogner
s.n. (Kew spirit collection 56675); K–N, Nerz s.n. (Kew spirit collection 56142).
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locular, ovules many, hemianatropous, placenta basal to intrusive basal, stylar region short and attenuate to inconspicuous,
stigma discoid-subcapitate. BERRY: subcylindric, light green,
bearing old stigma remains. SEED: ellipsoid to ovoid, testa
smooth, thin, cream-coloured to very light green, embryo
straight, endosperm copious. See Plates 46, 116D.
CHROMOSOMES: 2n = 40.
DISTRIBUTION: 2 spp.; Malay Archipelago:– Indonesia
(Sumatra), Malaysia (Peninsula).
ECOLOGY: tropical humid forest; rheophytes on rocks in
streams (F. sumatrensis), or forest floor terrestrials (F. mixta).
ETYMOLOGY: named after C.X. Furtado (1897–1980).
TAXONOMIC ACCOUNTS: Hotta (1981, 1985).
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47. Homalomena
Homalomena Schott in Schott & Endlicher, Melet. Bot. 20
(1832). LECTOTYPE: H. cordata Schott (Dracontium cordatum Houttuyn 1779, non Aublet 1775; see Nicolson in Taxon
16: 517. 1967).
SYNONYMS: Homalonema Endlicher, Gen. Pl. 238
(1837), orth. var.; Spirospatha Rafinesque, Fl. Tell. 4: 8 (1838,
“1836”); Cyrtocladon Griffith, Notul. Pl. Asiat. (Posthum. Pap.)
3: 147 (1851); Chamaecladon Miq. in Bot. Zeitung (Berlin)
14: 564 (1856); Adelonema Schott, Prodr. syst. Aroid. 316
(1860); Curmeria E.F. André, Ill. Hortic. 20: 45 (1873);
Diandriella Engler, Nova Guinea 8: 250 (1910).
HABIT: evergreen, usually aromatic (anise-scented) herbs,
stem shortly aerial, more rarely arborescent or hypogeal.
LEAVES: several, rarely distichous (H. geniculata). PETIOLE:
rarely aculeate or pubescent, rarely geniculate apically (H.
geniculata), sheath usually less than half as long as petiole.
BLADE: lanceolate, elliptic, oblong, subtriangular or cordate to
sagittate, rarely peltate, usually glabrous, rarely pubescent on
midrib and veins; primary lateral veins pinnate, running into
marginal vein, secondary and tertiary lateral veins parallelpinnate. INFLORESCENCE: 1–6 (or more) in each floral
sympodium. PEDUNCLE: shorter than petiole. SPATHE: erect,
often becoming green, more rarely white or yellow-green or
red, persistent, usually not constricted, ellipsoid to boatshaped, more rarely constricted between tube and blade and
then tube convolute, blade gaping at anthesis and afterwards
closing. SPADIX: shorter or subequal to spathe, stipitate or
sessile, female zone cylindric, male zone usually entirely fertile, contiguous with and longer than female zone, rarely
bearing staminodes basally, or very rarely separated by a ±
naked interstice. FLOWERS: unisexual, perigone absent.
MALE FLOWER: 2–4-androus, rarely 5–6-androus, very rarely
1-androus (H. monandra), stamens free, truncate apically, filaments absent or distinct, connective thick, thecae ovoid,
ellipsoid or oblong, opening by longitudinal slit, rarely by
transversal slit. POLLEN: extruded in strands, inaperturate,
ellipsoid to oblong, small (mean 22 µm., range 12–31 µm.),
exine perfectly psilate in most species, rarely obscurely fossulate. STERILE MALE FLOWERS: 2–4-androus, sometimes
present at base of fertile male zone, staminodia subprismatic,
somewhat rounded apically. FEMALE FLOWER: gynoecium
ovoid or oblong or subglobose, usually with single, anterior
staminode (rarely 2, very rarely 3), equalling or half as long
as ovary, sometimes absent (H. lindenii), ovary incompletely
2–4–(–5)-locular, ovules many, hemianatropous, funicle long,
placenta parietal and axile, stylar region shortly narrowed or
inconspicuous, stigma discoid, subhemispheric, subcapitate
or slightly 2–4-lobed. BERRY: obovoid or subglobose or
cylindric, locules many-seeded, rarely few-seeded. SEED:
ellipsoid or elongate ellipsoid, testa thick, distinctly or only
slightly costate, embryo axile, elongate, endosperm copious.
See Plates 47i–ii, 117A.
CHROMOSOMES: 2n = 38, 40, 42, 80.
DISTRIBUTION: ca. 110 spp.; tropical southeast Asia, Malay
Archipelago, tropical America:– Bangladesh, Bolivia, Brazil
(Amazonia, Central-West), Brunei, Burma, Cambodia, China
(Guandong, Guangxi, Hainan, Taiwan, Yunnan), Colombia,
Costa Rica, Ecuador, French Guiana, Guyana, India (Assam),
Indonesia (Borneo, Irian Jaya, Java, Moluccas, Sulawesi,
Sumatra, Sunda Is.), Laos, Malaysia (Borneo, Peninsula),
Panama, Papua New Guinea, Peru, Philippines, Singapore,
Solomon Is., Surinam, Thailand, ?Venezuela, Vietnam.
47. Homalomena
HOMALOMENEAE : HOMALOMENA
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G
E
A
C
B
F
D
H
Plate 47 (i). Homalomena. A, habit × 1/5; B, leaf × 1/2; C; leaf × 1/2; D, base of plant showing inflorescences × 1/2; E, leaf × 1/2; F, base
of plant showing inflorescences × 1/2; G, leaf × 1/2; H, leaf × 1/2. Homalomena sagittifolia: A, Boyce 252 (Kew slide collecttion); H. picturata: B, de Granville 5467 (K); H. rubescens: C–D, Keenan s.n. (K); H. havilandii: E, Ilias & Azahari S 35677 (K); F, Hetterscheid s.n. (Kew
slide collection); H. consobrina: G, de Wilde & de Wilde-Duyfjes 13495 (K); H. propinqua: H, Haviland 3134 (K).
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H
C
F
E
A
L
K
D
J
B
N
R
T
W
G
M
P
Q
S
U
V
Plate 47 (ii). Homalomena. A, infructescence, lower part of spathe removed to reveal berries × 1/1/2; B, inflorescence × 4; C, stamen ×
15; D, gynoecium and associated staminode × 15; E, gynoecium, longitudinal section × 15; F, gynoecium, transverse section × 24; G, inflorescence, spathe partly removed × 2/3; H, stamen × 10; J, gynoecium × 10; K, gynoecium, longitudinal section × 10; L, gynoecium, transverse
section × 16; M, inflorescence × 1; N, stamen × 10; P, gynoecium and associated staminode × 10; Q, gynoecium, longitudinal section × 10;
R, gynoecium, transverse section × 16; S, inflorescence × 1; T, stamen × 10; U, gynoecium × 10; V, gynoecium, longitudinal section × 10; W,
gynoecium, transverse section × 16. Homalomena vagans: A, Poulsen & de la Motte 273 (Kew spirit collection 58113); H. humilis: B–F, Sands
180 (Kew spirit collection 32886); H. speariae: G–L, Spear s.n. (Kew spirit collection 58911); H. rubra: M–R, Burkhill & Haniff 12792 (K &
Kew spirit collection 59026); H. hostifolia: S–W, Poulsen 268 (Kew spirit collection 59027).
HOMALOMENEAE : HOMALOMENA
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ECOLOGY: tropical humid forest, swamp forest, rarely in
open swamps; terrestrial in leaf litter on forest floor, along forest streams, on road banks, on well-drained slopes in moist
forest, rarely rheophytes.
NOTES: Engler (1912) recognized 3 sections:– sect.
Homalomena, sect. Chamaecladon, sect. Curmeria (tropical
America); Furtado (1939) recognized a fourth section, sect.
Cyrtocladon and Hotta (1967) a fifth, sect. Geniculatae.
ETYMOLOGY: Greek homalos (flat) and mênê (moon), translation of a vernacular name.
TAXONOMIC ACCOUNTS: Engler (1912), Furtado (1939),
Hotta (1967, 1982, 1984, 1985, 1986a, 1993), Bogner (1976b,
1986a), Bogner & Moffler (1984, 1985).
C
Tribe Anubiadeae
Tribe Anubiadeae Engler in Nova Acta Acad. Leopold.Carol. 39: 147 (1876).
Laticifers present, simple, articulated, roots with sclerotic
hypodermis; helophytic or rheophytic, stem rhizomatous,
creeping; petiole geniculate apically; leaf blade elliptic, lanceolate to hastate-tripartite, primary lateral veins pinnate,
forming single marginal vein, higher order venation parallelpinnate, finest transverse veins ± distinct; spathe boat-shaped,
unconstricted, persistent; flowers unisexual, perigone absent;
stamens connate into ± prismatic synandria, fused connectives thickened, ± truncate, thecae lateral or marginal, rarely
covering whole synandrium, dehiscing by longitudinal slit;
ovary (1–)2–3-locular, ovules many per locule, anatropous,
placenta axile, style narrower than ovary, stigma broad; berry
depressed-globose to obovoid; seeds small, ± ovoid to subcylindric, endosperm copious.
C
48. Anubias
Anubias Schott in Oesterr. bot. Wochenbl. 7: 398 (1857).
TYPE: A. afzelii Schott
SYNONYM: Amauriella Rendle, Cat. Talbot’s Nigerian
Pl. 115 (1913).
HABIT: evergreen herbs, rhizome thick, creeping, internodes
short. LEAVES: several. PETIOLE: usually smooth, rarely
shortly and sparsely spiny, geniculate apically, sheath relatively short. BLADE: lanceolate, ovate, elliptic, nearly
triangular to subsagittate, subcordate, auriculate, hastate to
trifid, mostly coriaceous, completely glabrous or midrib and
primary lateral veins densely pilose abaxially; primary lateral
veins pinnate, secondary lateral veins parallel-pinnate, tertiaries transverse between them. INFLORESCENCE: 1–3 in
each floral sympodium. PEDUNCLE: ± as long as petiole or
shorter. SPATHE: elliptic-ovate or ovate, not constricted, only
weakly differentiated into tube and blade, widely expanded
at anthesis, but always slightly convolute at base, closing
after anthesis and persistent to fruiting stage, uniformly
coloured, mostly green or cream to reddish tinged, paler
within. SPADIX: cylindric, shorter or sometimes much longer
than spathe, sessile or stipitate, female zone free, usually
densely flowered, rarely somewhat laxly so, shorter than
male and contiguous with it or rarely with few sterile or
irregular, bisexual flowers in between, male zone fertile to
apex. FLOWERS: unisexual, perigone absent. MALE
FLOWER: 3–8-androus, stamens connate, synandrium ±
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THE GENERA OF ARACEAE
48. Anubias
obpyramidal, filaments connate, sometimes fairly long, fused
connectives thick, fleshy, sometimes covered by thecae and
inconspicuous, often only incompletely connate at apex,
with shallow fissures in between, thecae lateral or marginal
or covering nearly the whole synandrium from apex to base
(A. pynaertii), dehiscing by longitudinal slit. POLLEN: inaperturate, subspheroidal to spherical, small (mean 24 µm., range
20–31 µm.), exine perfectly psilate to obscurely verrucate
and/or dimpled. FEMALE FLOWER: gynoecium depressedglobose to ovoid, ovary (1–)2–3-locular, ovules many per
locule, anatropous, placenta axile, stylar region narrower
than ovary, stigma broad, discoid, green, pink or white.
BERRY: depressed-globular to obovoid, green to pale green,
many-seeded. SEED: small, irregularly ovoid to subcylindric, testa rough, thickish, embryo axile, elongate,
endosperm copious. See Plates 48, 117B.
CHROMOSOMES: 2n = 48, 72.
DISTRIBUTION: 8 spp.; tropical west and central Africa:–
Angola, ?Benin, Cabinda, Cameroon, ?Central African
Republic, Congo, Equatorial Guinea (Bioko, Rio Muni),
Gabon, ?Gambia, Ghana, Guinea, ?Guinea-Bissau, Ivory Coast,
Liberia, Mali, Nigeria, Senegal, Sierra Leone, Togo, Zaïre.
ECOLOGY: tropical humid forest; helophytes or rheophytes,
forest swamps, in rocky places along streams, sometimes
completely submerged.
ETYMOLOGY: Classical name of an unknown herb,
anoubias (according to Schott).
TAXONOMIC ACCOUNTS: Engler (1915), Crusio (1979,
1987), Kasselmann (1995).
Tribe Schismatoglottideae
Tribe Schismatoglottideae Nakai, Ord. Fam. Trib. Nov. 218
(1943); Hotta in Acta Phytotax. Geobot. 33: 127–139 (1982).
Laticifers present, simple, articulated; terrestrial or rheophytic,
stem usually epigeal; petiole sheath usually with long,
marcescent, apical ligule (except most Schismatoglottis spp.);
blade apex with tubular mucro (except most Schismatoglottis
spp.), primary lateral veins pinnate, forming single, usually
prominent marginal vein, higher order venation parallel-pin-
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Q
P
R
S
V
U
T
F
E
H
A
G
C
J
M
D
L
B
K
N
W
Plate 48. Anubias. A, habit × 1/2; B, inflorescence × 1; C, detail of male zone of spadix × 5; D, detail of female zone of spadix × 5; E, synandrium, side view × 10; F, synandrium, top view × 10; G, gynoecium, longitudinal section × 10; H, gynoecium, transverse section × 10; J, habit
× 1/2; K, habit × 1/2; L, synandrium, side view × 10; M, synandrium, top view × 10; N, gynoecium, longitudinal section × 10; P, synandrium,
side view × 10; Q, synandrium, top view × 10; R, gynoecium, longitudinal section × 10; S, inflorescence × 1; T, synandrium, side view × 10; U,
synandrium, top view × 10; V, gynoecium, longitudinal section × 10; W, leaf × 1/2. Anubias afzelii: A, Morton & Gledhill SL 1169 (K); B, Hepper
2504 (K); C–H, Cult. Kew 1963–02202 (Kew spirit collection 50101); A. gracilis: J, Morton & Gledhill SL 1929 (K); A. barteri var. barteri: K, Onochie
& Okafor IFH 36037 (K); L–N, Brenan 9257 (Kew spirit collection 25469); A. hastifolia: P–R, Bogner s.n. (Kew spirit collection 7100); A. pynaertii: S, W. Crusio, Die Gattung Anubias Schott, p. 38 (1987); T–V, Bogner 699 (K & Kew spirit collection 56680); A. gigantea: W, Bos 1914 (K).
ANUBIADEAE : ANUBIAS
181
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nate; inflorescence usually 1 (except Schismatoglottis);
peduncle usually elongating in fruit; spathe tube persistent,
blade usually white (except Piptospatha), deciduous at anthesis, rarely marcescent (in Schismatoglottis beccariana,
Hottarum lucens); flowers unisexual, perigone absent; stamens usually free, sometimes connate by fused filaments,
filaments often ± elongated, thecae truncate or horned, nearly
always dehiscing by apical pore; ovary 1-locular, ovules
orthotropous to hemiorthotropous (except Schismatoglottis),
stigma usually sessile (except Schismatoglottis); seed testa
usually costate, embryo axile, endosperm copious.
C
49. Schismatoglottis
Schismatoglottis Zollinger & Moritzi in Moritzi, Syst.
Verzeichnis Zollinger, 83 (1846). TYPE: S. calyptrata
(Roxburgh) Zollinger & Moritzi (Calla calyptrata Roxburgh).
SYNONYMS: Philonotion Schott in Oesterr. bot.
Wochenbl. 7: 421 (1857); Apoballis Schott in Oesterr. bot.
Zeitschr. 8: 318 (1858); Apatemone Schott, Gen. Aroid. t. 57
(1858); Colobogynium Schott in Oesterr. bot. Zeitschr. 15: 34
(1865); Nebrownia O. Kuntze, Rev. Gen. 2: 742 (1891).
HABIT: small to large, evergreen herbs, rarely shortly, densely
or long-pubescent, stem rhizomatous or epigeal, shortly erect.
LEAVES: numerous, rarely distichous. PETIOLE: sheath less
than half petiole length, sometimes with long apical ligule.
BLADE: narrow-elliptic, elliptic, lanceolate, oblanceolate,
ovate, obovate, cordate, cordate-sagittate, sometimes variegated with paler or silvery green, white or yellow; primary
lateral veins pinnate, running into distinct marginal vein, secondary and tertiary laterals parallel-pinnate, higher order
venation transverse-reticulate. INFLORESCENCE: 1–3 (or
more) in each floral sympodium. PEDUNCLE: shorter than
petiole. SPATHE: constricted between tube and blade, sometimes only slightly so, rarely not at all, tube convolute,
persistent, blade thinner, erect, broadly boat-shaped, gaping
and then caducous at anthesis, rarely marcescent, usually
white to cream, sometimes greenish-yellow, very rarely pink,
cuspidate to acuminate. SPADIX: shorter than or equalling
spathe, lower part consisting of cylindric to conoid female
zone, free or partially adnate to spathe, sometimes bearing
sterile organs at the very base, upper part of spadix usually
± clavate, sometimes subcylindric, either fertile male below
and sterile terminally, or sterile below and fertile male terminally, or sterile below, centrally fertile male and sterile
terminally, lowermost sterile zone sometimes very laxly flowered, often constricted. FLOWERS: unisexual, perigone
absent. MALE FLOWER: 2–3-androus, stamens very short to
long, mostly free, filaments usually well-developed, sometimes connate basally, always with distinctive tannin cells
(dark in dried specimens), connective usually rather slender,
sometimes thicker apically, anthers truncate, often concave
apically, thecae opposite, cylindric or obconic to ovoid,
dehiscing by apical, broadly elliptic, or bilobed pore.
POLLEN: extruded in strands, inaperturate, ellipsoid to
oblong, small (mean 20 µm., range 15–26 µm.), exine perfectly psilate, rarely rugulate to verruculate (S. spruceana).
STERILE MALE FLOWERS: staminodes less compressed than
stamens, obpyramidal to clavate, usually truncate, short to
long. FEMALE FLOWER: gynoecium sometimes accompanied by 1–4 clavate, rarely peltate staminodes with generally
distinctly swollen apices, or rarely with sterile flowers scattered among gynoecia, ovary 1-locular, ovules (1–)few to
many, anatropous to hemianatropous, funicle rather long,
placentae 1–4, parietal, usually extending from base to apex
of locule, stylar region inconspicuous or shortly conoid,
stigma discoid to capitate, small to as wide as ovary. BERRY:
oblong to globose, green or dull yellow or deep red, few- to
many-seeded. SEED: ellipsoid, testa costate, embryo straight,
elongate, endosperm copious. See Plates 49i–iii, 117C.
CHROMOSOMES: 2n = 26, 39, 52.
DISTRIBUTION: ca. 120 spp.; tropical Asia, Malay Archipelago,
tropical South America:– Brazil (Amazonia), Brunei, Burma,
Cambodia, China (Guandong, Guangxi, Hainan, Yunnan),
Colombia, French Guiana, ?Guyana, Indonesia (Borneo, Irian
Jaya, Java, Moluccas, Sulawesi, Sumatra, Sunda Is.), Laos,
Malaysia (Borneo, Peninsula), Papua New Guinea, Peru,
Philippines, Solomon Is., Surinam, Thailand, Vanuatu,
Venezuela, Vietnam.
ECOLOGY: tropical humid forest; terrestrial, forest floor,
sometimes rheophytes.
NOTES: Hotta (1966a) recognized 5 informal groups in the
Bornean species:– S. homalomenoidea group, S. monoplacenta group, S. barbata group, S. acutifolia group, S.
calyptrata group; the neotropical species earlier recognized
as the genus Philonotion now form sect. Philonotion
(Bunting 1960b).
49. Schismatoglottis
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THE GENERA OF ARACEAE
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B
C
D
A
E
Plate 49 (i). Schismatoglottis. A, habit × 1/2; B, detail of leaf tip tubule × 8; C, habit × 1/2; D, habit × 1/2; E, habit × 1/2. Schismatoglottis
gillianae: A–B, Coode 6313 (K); S. spruceana: C, Plowman 13527A (K); S. hottae: D, Johns 6872 (K); S. convolvula: E, Mamit S42102 (K).
S C H I S M ATO G L OT T I D E A E : S C H I S M ATO G L OT T I S
183
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D
A
B
C
E
F
G
Plate 49 (ii). Schismatoglottis. A, leaf × 1/2; B, leaf × 1/2; C, leaf × 1/2; D, leaf × 1/2; E, leaf × 1/2; F, leaf × 1/2; G, leaf × 1/2. Schismatoglottis
hastifolia: A, Clemens & Clemens 29493 (K); S. calyptrata: B, Beaman 10632 (K); S. ferruginea: C, Dransfield 6871 (K); D, S. hottae: Johns
6872 (K); S. crispata: E, Cult. Veitch, June & July 1881 (K); S. spruceana: F, Plowman 13527A (K); S. gillianae: G, Coode 6313 (K).
ETYMOLOGY: Greek schisma, schismatos (separating) and
glôtta (tongue); refers to the deciduous spathe blade.
TAXONOMIC ACCOUNTS: Engler (1912), Bunting (1960b),
Hotta (1965, 1966a), Bunting & Steyermark (1969), Bogner &
Hotta (1983b), Bogner (1988a).
C
50. Piptospatha
Piptospatha N.E. Brown in Gard. Chron., ser. 2, 11: 138
(1879). TYPE: P. insignis N.E. Brown
SYNONYMS: Rhynchopyle Engler in Bot. Jahrb. 1: 183
(1880) (“1881”); Gamogyne N.E. Brown in J. Bot. 20: 195
(1882).
HABIT: small to medium-sized evergreen herbs, stem erect
or decumbent. LEAVES: several. PETIOLE: sheath short with
long, marcescent ligule. BLADE: elongate-lanceolate to elliptic or oblanceolate, coriaceous, apex with tubular mucro;
primary lateral veins pinnate, running into distinct marginal
vein, secondary laterals and higher order venation parallelpinnate. INFLORESCENCE: solitary, usually nodding.
PEDUNCLE: subequal to or longer than petiole. SPATHE:
stoutly ellipsoid, not constricted, often pink, lower part persistent and cup-like, upper part slightly gaping at anthesis,
caducous or deliquescent, cuspidate to acuminate. SPADIX:
sessile with ± oblique insertion, sometimes with sterile
female flowers at extreme base, female zone cylindric,
shorter and contiguous with male, or separated by a short
184
THE GENERA OF ARACEAE
zone of sterile male flowers, male zone cylindric, equal in
thickness to female, obtuse, fertile to apex or with a few
sterile terminal flowers. FLOWERS: unisexual, perigone
absent. MALE FLOWER: 1–2-androus, stamens free, compressed, anthers truncate, connective ± flat or expanded
apically or with conical beak (P. insignis), overtopping thecae, thecae oblong-ellipsoid, dehiscing by apical pore.
POLLEN: inaperturate, ellipsoid, small to medium-sized
(mean 25 µm.), exine psilate. STERILE MALE FLOWERS:
apparently composed of a single truncate, subclavate, prismatic staminode. FEMALE FLOWER: gynoecium free or
cohering to neighbouring ones, ovary 1-locular, ovules
many, hemiorthotropous to almost orthotropous and erect,
funicle long, placentae 2–4, parietal or parietal and basal,
stigma ± sessile or stylar region inconspicuous, as broad as
ovary, contiguous with adjacent ones. BERRY: obovoid,
green. SEED: elongate-ellipsoid to cylindric, with long,
curved micropylar appendage, testa slightly costate, embryo
elongate, endosperm copious. See Plates 50, 117D.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 10 spp.; Brunei, Indonesia (Borneo),
Malaysia (Borneo, Peninsula), Thailand.
ECOLOGY: tropical humid forest; rheophytes.
NOTES: sect. Piptospatha, sect. Gamogyne (N.E. Brown) M.
Hotta. The latter section is only weakly defined, by the presence of superficially connate gynoecia.
ETYMOLOGY: Greek piptô (I fall) and spathê (spathe); refers
to the deciduous spathe blade.
TAXONOMIC ACCOUNTS: Engler (1912), Hotta (1965).
26c Tribes & Genera Acro 17/7/97 17:46 Page 185
K
D
L
E
P
B
H
A
F
M
G
N
C
J
S
T
BB
Y
W
Q
R
U
V
Z
AA
X
Plate 49 (iii). Schismatoglottis. A, infructescences with associated petiole × 2/3; B, inflorescence × 1; C, spadix × 2; D, staminode × 20;
E, stamens × 20; F, gynoecium × 20; G, gynoecium, longitudinal section × 20; H, gynoecium, transverse section × 30; J, spadix × 2; K, staminode × 20; L, stamen × 20; M, gynoecium × 20; N, gynoecium, longitudinal section × 20; P, gynoecium, transverse section × 30; Q,
inflorescence × 1; R, spadix × 2; S, staminode × 20; T, stamen × 20; U, gynoecium × 20; V, gynoecium, longitudinal section × 20; W, gynoecium, transverse section × 30; X, spadix, spathe partly removed × 2; Y, stamen × 20; Z, gynoecium × 20; AA, gynoecium, longitudinal section
× 20; BB, gynoecium, transverse section × 30. Schismatoglottis neoguinensis: A, Floyd 6445 (K); S. tecturata: B–H, Bogner 1554 (Kew spirit
collection 45228); S. spruceana: J–P, Plowman 13527A (K & Kew spirit collection 58039); S. crispata: Q–W, Boyce 672 (Kew spirit collection
59035); S. calyptrata: X–BB, Hay 2007, Cult. Kew 1982–04973 (Kew spirit collection 46560).
S C H I S M ATO G L OT T I D E A E : S C H I S M ATO G L OT T I S
185
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E
B
F
D
C
H
K
N
A
L
M
G
J
Plate 50. Piptospatha. A, habit × 1/2; B, seed × 15; C, habit × 1/2; D, spadix × 2; E, stamen × 15; F, gynoecia, right hand gynoecium longitudinally sectioned × 10; G, habit × 1/2; H, detail of leaf tip tubule × 6; J, spadix × 2; K, stamen × 15; L, gynoecium × 15; M, gynoecium,
longitudinal section × 15; N, staminode × 15. Piptospatha elongata: A, Chew, Corner & Stainton 2501 (K); B, Bogner 2153 (Kew spirit collection 59089); P. burbidgei: C–F, Richards 1091 (K & Kew spirit collection 58020); P. ridleyi: G, Burkill 2577 (K); H, Sinclair 10577 (K); J–M,
Bogner 2120 (Kew spirit collection 57278).
186
THE GENERA OF ARACEAE
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50. Piptospatha
C
51. Hottarum
Hottarum Bogner & Nicolson in Aroideana 1: 72 (1979,
“1978”). TYPE: H. truncatum (M. Hotta) Bogner & Nicolson
(Microcasia truncata M.Hotta).
SYNONYM: Based on Microcasia sect. Truncatae M. Hotta
in Mem. Coll. Sci. Univ. Kyoto, ser. B, Biol., 32: 21 (1965).
HABIT: evergreen herbs, stem short, ± erect, epigeal, internodes short. LEAVES: numerous. PETIOLE: sheath with long,
free ligule. BLADE: elliptic, oblong-elliptic, or narrowly elliptic, coriaceous, apex with tubular mucro; primary lateral
veins pinnate, running into distinct marginal vein, higher
order venation parallel-pinnate. INFLORESCENCE: 1, rarely 2
in each floral sympodium. PEDUNCLE: subequal to petiole
in flower, elongating in fruit. SPATHE: constricted or not,
uniformly coloured, or green below and white above, ellipsoid to obovoid at anthesis, lower part convolute, cup-shaped
and persistent after anthesis, upper part only opening slightly at anthesis, caducous, or marcescent and then evanescent
(H. lucens), apex acuminate to cuspidate. SPADIX: subcylindric, usually free or sometimes adnate to spathe for
two-thirds of length (H. lucens), female zone subcylindric,
sometimes with sterile flowers at base, either contiguous
with male, or with a few sterile male flowers in between,
male zone as thick or thicker than female, apical zone composed of sterile male flowers, in H. lucens fertile only where
exposed at anthesis by spathe opening and otherwise com-
posed entirely of sterile male flowers. FLOWERS: unisexual,
perigone absent. MALE FLOWER: (1–)2–3(–4)-androus, stamens truncate at apex, filaments distinct, sometimes connate
basally, connective broad, thick, thecae lateral, opposite, not
horned, dehiscing apically by single pore or two pores confluent into a short transverse slit. POLLEN: inaperturate,
ellipsoid or globose, small (mean 14 µm., range 10–17 µm.),
exine perfectly psilate or irregularly dimpled. STERILE MALE
FLOWERS: composed of truncate, prismatic staminodes.
FEMALE FLOWER: usually consisting of gynoecium alone,
sometimes also with a clavate staminode in basal flowers
(or lateral flowers when female zone adnate to spathe), ovary
depressed-globose, 1-locular, ovules 10–15, orthotropous,
funicle long, placenta basal, stigma sessile, discoid or subcapitate. BERRY: ± globose, many-seeded, whitish green with
brownish stigma remnants. SEED: ellipsoid to elongate, testa
whitish to brownish, costate, embryo straight, elongate,
endosperm copious. See Plates 51, 118A.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 6 spp.; Brunei, Indonesia (Borneo), Malaysia
(Borneo).
ECOLOGY: tropical humid forest; rheophytes.
NOTES: Hottarum lucens is rather different from the other
species.
ETYMOLOGY: named after Mitsuru Hotta (born 1935) and
Arum.
TAXONOMIC ACCOUNTS: Bogner (1983b,1984b), Bogner &
Hotta (1983a).
51. Hottarum
S C H I S M ATO G L OT T I D E A E : H OT TA R U M
187
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C
E
D
A
L
B
N
F
G
H
J
M
P
K
Q
Plate 51. Hottarum. A, habit × 2/3; B, spadix × 2; C, stamen × 16; D, staminode × 16; E, gynoecium, longitudinal section × 16; F, spadix ×
2; G, stamen × 16; H, staminode × 16; J, gynoecium with associated staminode; K, habit × 2/3; L, detail of leaf tip tubule × 6; M, spadix × 3;
N, stamen × 16; P, gynoecium × 16; Q, gynoecium, longitudinal section × 16. Hottarum lucens: A, Elsener 184 (K); B–E, Bogner 1439 (Kew
spirit collection 45223); H. sarikeense: F–J, Bogner 1553 (Kew spirit collection 45681); H. kinabaluense : K, M–Q, Edwards 2162 (Kew spirit
collection 54425); L, Clemens & Clemens 29135 (K).
188
THE GENERA OF ARACEAE
26d Tribes & Genera Acro 18/7/97 6:27 Page 189
C
52. Bucephalandra
Bucephalandra Schott, Gen. Aroid. t. 56 (1858). TYPE: B.
motleyana Schott
SYNONYM: Microcasia Beccari in Bull. Soc. Tosc. Ortic.
4: 180 (1879).
HABIT: minute to medium-sized evergreen herbs, stem creeping, apex upright. LEAVES: numerous. PETIOLE: sheath with
long marcescent ligule. BLADE: elliptic, elliptic-oblong, linearoblanceolate to obovate, coriaceous, punctate below, apex
with tubular mucro; primary lateral veins pinnate, running into
distinct marginal vein, higher order venation parallel-pinnate.
INFLORESCENCE: solitary. PEDUNCLE: subequal to petiole at
anthesis, elongating later. SPATHE: ellipsoid, cuspidate, not
constricted, lower part light green, convolute, broadly funnelshaped, persistent, enclosing developing fruits, upper part
white, gaping at anthesis, caducous immediately afterwards.
SPADIX: sessile, shorter than spathe, with a few pistillodes at
extreme base, female zone cylindric, narrower than upper
parts, with gynoecia in 2–6 spirals, separated from male zone
by a few rows (usually 2) of flattened, smooth, scale-like staminodes, male zone with 2–5 rows of flowers, terminal
appendix globose or ellipsoid to subcylindric, composed of
truncate, obpyramidal to subcylindric, apically papillose staminodes, the uppermost ± connate. FLOWERS: unisexual,
perigone absent. MALE FLOWER: 1-androus, filament distinct
but short, flattened, connective ± inconspicuous, thecae ellipsoid, extrorse, dehiscing by pore at tip of conspicuous apical
horn. POLLEN: extruded in a droplet, inaperturate, ellipsoid,
medium-sized (mean 29 µm., range 28–30 × 20–24 µm.), exine
smooth (psilate). FEMALE FLOWER: gynoecium depressedglobose, 1-locular, ovules many, orthotropous, attenuate
towards micropyle, funicle distinct, placenta basal, stigma sessile, discoid, slightly concave in centre, narrower than ovary.
BERRY: globose to ellipsoid with numerous seeds. SEED: narrow-ellipsoid, with long, curved micropylar appendage, testa
very slightly longitudinally ribbed to scabrous, embryo straight,
elongate, endosperm copious. See Plates 52, 118B.
CHROMOSOMES: 2n = ca. 26.
DISTRIBUTION: 3 spp.; Brunei, Indonesia (Borneo), Malaysia
(Borneo).
ECOLOGY: tropical humid forest; rheophytes.
ETYMOLOGY: Greek bous (bull or cow), cephalê (head) and
anêr, andros (man).
TAXONOMIC ACCOUNTS: Engler (1912), Bogner (1980a,
1984b), Boyce (1995a), Boyce, Bogner & Mayo (1995).
C
53. Phymatarum
Phymatarum M. Hotta in Mem. Coll. Sci. Kyoto Imp. Univ.,
ser. B, 32: 29 (1965). TYPE: P. borneense M. Hotta
HABIT: small evergreen herbs, stem creeping to decumbent. LEAVES: several. PETIOLE: sheath fairly short with
long marcescent ligule. BLADE: narrowly elliptic, somewhat coriaceous, apex with tubular mucro; primary lateral
veins pinnate, running into conspicuous marginal vein, secondary and tertiary laterals parallel-pinnate, higher order
venation inconspicuously transverse-reticulate. INFLORESCENCE: solitary. PEDUNCLE: erect, shorter or subequal to
petiole. SPATHE: constricted between tube and blade, tube
convolute, persistent, green, blade longer, boat-shaped and
gaping at anthesis, whitish, cuspidate, caducous after anthesis. SPADIX: extreme base bearing a few pistillodes or not,
female zone conoid to subcylindric, basally adnate to
spathe, separated from male zone by cylindric to ellipsoid
zone of sterile male flowers, male zone very short and
slightly narrower, terminal appendix much longer, elongate-conoid, bearing sterile male flowers. FLOWERS:
unisexual, perigone absent. MALE FLOWER: apparently 1androus, free, filament short, connective inconspicuous,
thecae tuberculate, ending in curved horn, dehiscing by
apical pore. STERILE MALE FLOWERS: staminodes subprismatic, tuberculate, flattened or excavated, lowermost
either with or without central, short, subulate projection,
uppermost more slender, relatively longer, otherwise similar but never with projections. POLLEN: inaperturate,
ellipsoid, small (mean 19 µm., range 17–22 µm.) exine psilate. FEMALE FLOWER: gynoecium depressed- globose,
ovary 1-locular, ovules many, hemiorthotropous, funicle
long, placenta basal, stigma sessile, slightly concave centrally, narrower than ovary, very thinly discoid. BERRY:
many-seeded, depressed-obovoid, slightly furrowed, greenish-white. SEED: ellipsoid, with long micropylar appendage,
testa costate, embryo elongate, straight, endosperm copious.
See Plates 53, 118C.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 3 spp.; Brunei, Indonesia (Borneo), Malaysia
(Borneo).
ECOLOGY: tropical humid forest; rheophytes.
ETYMOLOGY: Greek phyma, phymatos (tumour, growth)
and Arum.
TAXONOMIC ACCOUNTS: Bogner (1984a).
52. Bucephalandra
S C H I S M ATO G L OT T I D E A E : P H Y M ATA R U M
189
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C
P
Q
A
D
B
M
F
G
N
L
E
K
H
J
Plate 52. Bucephalandra. A, habit × 2/3; B, habit × 2/3; C, detail of leaf tip tubule × 6; D, inflorescence × 1; E, spadix × 5; F, upper spadix
staminode × 15; G, stamen × 15; H, mid–spadix staminode × 15; J, gynoecium, longitudinal section × 15; K, lower spadix pistillode × 15; L,
base of plant × 2/3; M, leaf × 2/3; N, spadix × 5; P, habit × 2/3; Q, spadix × 5. Bucephalandra motleyana: A, Mamit S 33470 (K); B, Chew
1111 (K); C, Marsh & Simpson 21 (Kew spirit collection 57279); D–K, Bogner 1447 (Kew spirit collection 45261); B. gigantea: L–M, Endert
4580 (K); N, Endert 4580 (Kew spirit collection 58050); B. catherineae: P–Q, de Vogel & Cribb 9210 (Kew spirit collection 57575).
190
THE GENERA OF ARACEAE
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D
A
B
E
K
F
G
H
J
C
Plate 53. Phymatarum. A, habit × 2/3; B, detail of leaf tip tubule × 6; C, spadix × 2; D, staminode from appendix × 8; E, stamen × 8; F,
staminode from lower zone of sterile male flowers × 8; G, gynoecium–associated staminode × 8; H, gynoecium × 8; J, gynoecium, longitudinal section × 8; K, seed × 4. Phymatarum borneense: A–B, Bogner 1506 (K); C–J, Boyce 341 (Kew spirit collection 56097); K, Bogner 2159
(Kew spirit collection 58007).
S C H I S M ATO G L OT T I D E A E : P H Y M ATA R U M
191
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53. Phymatarum
C
54. Aridarum
Aridarum Ridley in J. Bot. 51: 201 (1913). TYPE: A. montanum Ridley
HABIT: small to medium-sized, evergreen herbs, stem decumbent, erect distal part sometimes rather long. LEAVES: several,
spiral or rarely distichous (A. annae). PETIOLE: sheath with
long, marcescent ligule. BLADE: coriaceous, linear to elliptic,
apex with tubular mucro; primary lateral veins pinnate, weakly
or not differentiated, running into distinct marginal vein, higher
order venation parallel-pinnate. INFLORESCENCE: solitary,
sometimes ± nodding. PEDUNCLE: subequal or longer than
petiole, sometimes ± deflexed at apex. SPATHE: stoutly ellipsoid, not constricted, convolute and gaping at apex only or
broadly boat-shaped and widely gaping to base, lower part
persistent, green, upper part caducous, white, cuspidate to
acuminate at apex. SPADIX: sessile, cylindric, normally with a
few sterile flowers at extreme base, female zone cylindric,
shorter than male and separated from it by equally thick zone
of sterile male flowers, male zone equally thick, with shorter
apical zone of sterile flowers, apex obtuse. FLOWERS: unisexual, perigone absent. MALE FLOWER: 1–2-androus,
filaments distinct to very short, free to connate, connective
slightly to deeply excavated, thecae either opposite or paired
54. Aridarum
192
THE GENERA OF ARACEAE
on one side and situated inside or outside connective cavity,
apically narrowed into long or short horn, dehiscing by apical pore. POLLEN: inaperturate, ellipsoid-oblong, small (mean
23 µm., range 16–31 µm.), exine psilate. STERILE MALE
FLOWERS: consisting of prismatic to obpyramidal, truncate
staminodes with or without a small, central, apical cavity.
FEMALE FLOWER: gynoecium shallow, laterally compressed,
subhexagonal to subglobose, ovary 1-locular, ovules many,
orthotropous to hemiorthotropous, funicle distinct, erect, placenta basal, stigma sessile, slightly concave centrally, as broad
as ovary, contiguous with neighbouring stigmas. BERRY: globose or ellipsoid to cylindric, stigma remnant persistent,
infructescence globular to slightly elongate. SEED: ellipsoid,
elongate, testa longitudinally costate, embryo elongate,
endosperm present. See Plates 54, 118D.
CHROMOSOMES: 2n = 24.
DISTRIBUTION: 7 spp.; Brunei, Malaysia (Borneo).
ECOLOGY: tropical humid forest; rheophytes.
NOTES: 2 sections recognized by Hotta (1965):– sect.
Aridarum, sect. Caulescentia.
ETYMOLOGY: Latin aridus (dry) and Arum (the genus); a
misnomer as Aridarum species are rheophytes and do not
occur in dry habitats.
TAXONOMIC ACCOUNTS: Engler in Engler & Krause (1920),
Hotta (1965), Bogner (1979b, 1981a, 1983a).
26d Tribes & Genera Acro 18/7/97 6:28 Page 193
K
N
P
L
M
B
J
E
U
F
C
A
G
H
R
D
S
T
Q
Plate 54. Aridarum. A, habit × 2/3; B, spadix × 6; C, detail of stamens × 6; D, detail of gynoecia × 6; E, stamen × 10; F, stamen, three quarter
view × 10; G, gynoecium × 10; H, gynoecium, longitudinal section × 10; J, habit × 2/3; K, detail of leaf tip tubule × 3; L, detail of stamens ×
6; M, detail of gynoecia × 6; N, stamen × 10; P, gynoecium × 10; Q, habit × 2/3; R, detail of stamens × 6; S, detail of gynoecia × 6; T, gynoecium × 10; U, stamen × 10. Aridarum nicolsonii: A–H, Bogner 1440 (K & Kew spirit collection 56427); A. burttii: J–K, Chai S34072 (K); L–P,
Burtt 5116 (Kew spirit collection 34396); A. caulescens var. caulescens : Q–U, Boyce 250 (K & Kew spirit collection 56095).
S C H I S M ATO G L OT T I D E A E : A R I DA R U M
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55. Heteroaridarum
Heteroaridarum M. Hotta in Acta Phytotax. Geobot. 27
(3–4): 63 (1976). TYPE: H. borneense M. Hotta
HABIT: evergreen herb, stem short, erect. LEAVES: several, distichous. PETIOLE: sheath with long, narrowly
triangular ligule. BLADE: narrowly elliptic-oblanceolate,
coriaceous; primary lateral veins pinnate, running into marginal vein, higher order venation parallel-pinnate.
INFLORESCENCE: solitary. PEDUNCLE: subequal to petiole.
SPATHE: slightly constricted, tube convolute, green, persistent, blade white, acuminate, caducous. SPADIX: sessile,
female zone short, separated from male by short zone of
sterile flowers, male zone much longer, subcylindric-ellipsoid, fertile to apex. FLOWERS: unisexual, perigone absent.
MALE FLOWER: 3-androus, filaments as long as anthers,
connate, with conspicuous tannin cells, connective thick,
all three stamens parallel to one another, 2 outermost much
larger with shortly horned thecae, central one much smaller
with hornless thecae, all thecae opening by apical pore.
POLLEN: unknown. STERILE MALE FLOWERS: composed
of slender, basally connate, clavate, truncate staminodes.
FEMALE FLOWER: gynoecium depressed-globose, ovary
1-locular, ovules many, hemiorthotropous, placentae 2,
basal and apical, apical one bearing smaller and apparently
sterile ovules, stigma sessile, as broad as ovary, concave
centrally. BERRY: unknown. SEED: unknown. See Plate 55.
CHROMOSOMES: unknown.
DISTRIBUTION: 1 sp.; Malaysia (Borneo).
ECOLOGY: tropical humid forest; rheophyte.
ETYMOLOGY: Greek heteros (different) and Aridarum.
Tribe Cryptocoryneae
C
Tribe Cryptocoryneae Blume, Rumphia 1: 83 (1836).
Laticifers absent in foliage leaves but present in stem, roots
and cataphylls (Sivadasan, pers. comm.); aquatic to amphibious, stem rhizomatous, intravaginal squamules present;
primary lateral veins pinnate, forming single marginal vein,
higher order venation reticulate; inflorescence 1; spathe tube
with margins connate, tube usually ± swollen basally to
C
A
G
B
E
F
H
D
J
K
Plate 55. Heteroaridarum. A, habit × 1/3; B, leaf × 1/3; C, detail of leaf tip tubule × 4; D, spadix × 2; E, stamens, side view × 10; F, stamens,
front view × 10; G, stamens, longitudinal section × 10; H, staminodes × 10; J, gynoecium × 10; K, gynoecium, longitudinal section × 10.
Heteroaridarum borneense: A–K, Abbe et al. 9845 (SAR).
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THE GENERA OF ARACEAE
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55. Heteroaridarum
form a “kettle”, blade lanceolate to cordate, twisted or longspiralled, often long-caudate; spadix entirely enclosed in
spathe tube “kettle”, sterile terminal appendix apically adnate
to spathe at apex of kettle; flowers unisexual, perigone
absent; male flower 1(–2)-androus, stamens free, anther sessile or with short filament, excavated at apex with prominent
margins, connective inconspicuous, thecae ending in prominent horn, dehiscing by apical pore, pollen exine smooth
(psilate); ovary 1-locular, ovules orthotropous; embryo elongate, endosperm copious.
C
56. Lagenandra
Lagenandra Dalzell in Hooker’s J. Bot. Kew Gard. Misc. 4:
289 (1852). TYPE: L. toxicaria Dalzell
Laticifers absent in foliage leaves but present in stem, roots
and cataphylls (Sivadasan, pers. comm.). HABIT: small to
medium-sized evergreen herbs, rhizome creeping, thick,
rarely stoloniferous (L. nairii). LEAVES: several, cataphylls
conspicuous. PETIOLE: sheath fairly long. BLADE: ptyxis
involute, ovate, lanceolate, elliptic to almost linear, usually
glabrous (hairy in L. nairii), coriaceous; primary lateral veins
pinnate, weakly differentiated, running into inconspicuous
marginal vein, secondary laterals parallel to primaries, higher
order venation transverse-reticulate. INFLORESCENCE: solitary. PEDUNCLE: short, rarely long (L. bogneri), erect at
anthesis, deflexed in fruit. SPATHE: marcescent, very thickwalled, outer surface green to purple, completely smooth or
very warty on blade, margins basally connate into cylindric
or ellipsoid tube (“kettle”), tube sometimes narrowing apically within (by thickening of walls, thus not apparent from
outside), inner surface of lower region usually longitudinally furrowed, mouth of tube occluded by transverse,
centrally perforated septum with separate transverse flap
situated immediately below septum and partly or completely
covering male zone of spadix, blade straight or twisted,
opening only slightly by narrow longitudinal or spiral slit, or
widely gaping, apex acute to long-caudate, inside smooth,
uniformly warty or with warts in transverse bands, or cov-
ered with shortly branched processes, distinct “collar”
around mouth of kettle present or absent. SPADIX: slender,
female zone usually with 3–5(–7) spirals of gynoecia, rarely
in pseudowhorl (L. nairii) or true whorl (L. gomezii), separated from male zone by slender naked axis, male zone
cylindric to ellipsoid, terminal appendix small, conoid, apically adnate to spathe behind spathe flap; olfactory bodies
present or absent above female flowers. FLOWERS: unisexual, perigone absent. MALE FLOWER: 1(–2)-androus,
stamens free, anthers sessile or with short thick filaments,
apex somewhat excavated with prominent thickened margin, connective inconspicuous, thecae opposite, each
narrowed into an erect horn usually exceeding, rarely
equalling thickened margin and dehiscing by apical pore.
POLLEN: inaperturate, ellipsoid to ellipsoid-oblong, mediumsized (mean 36 µm., range 35–38 µm.), exine perfectly
56. Lagenandra
C RY P TO C O RY N E A E : L A G E N A N D R A
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26d Tribes & Genera Acro 18/7/97 6:29 Page 196
J
K
H
A
B
D
F
G
E
C
Plate 56. Lagenandra. A, habit × 2/3; B, infructescence × 1; C, habit × 2/3; D, leaf × 2/3; E, inflorescence with spadix detail viewed through
opened kettle × 2; F, inflorescence with spadix detail viewed through opened kettle × 1; G, spadix × 3; H, stamen × 20; J, gynoecium × 10;
K, gynoecium, longitudinal section × 10. Lagenandra toxicaria: A, Barnes 641 (K); Meebold 8877 (K); B, Barnes 1003 (Kew spirit collection
22447); L. koenigii: C–D, Bogner 564 (K & Kew spirit collection 57394); L. nairii: E, Bogner 1847 (Kew spirit collection 53950); L. dewitii:
F–K, Bogner 1749 (Kew spirit collection 49709).
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psilate. FEMALE FLOWER: gynoecium free, broadly ellipsoid to globose, ovary 1-locular, ovules 1–12(–15),
orthotropous, tapering towards micropyle, funicle short,
bearing very long trichomes, placenta basal, stylar region
thick, usually short, rarely long, stylar region and upper part
of ovary often conspicuously warty, stigma discoid to hemispheric, sometimes oblique, relatively broad. BERRY: free,
obovoid to prismatic-ellipsoid, often apically warty, rarely
smooth, at maturity pericarp splitting and revolute basally to
release seeds, infructescence usually globose, deflexed, prostrate. SEED: ellipsoid to narrowly ellipsoid or subcylindric,
testa longitudinally costate, dark brown, embryo elongate,
endosperm copious. See Plates 56, 119A.
CHROMOSOMES: 2n = 36, 72.
DISTRIBUTION: 14 spp.; tropical south Asia:– Bangladesh,
India (Assam, south India), Sri Lanka.
ECOLOGY: tropical humid forest; usually helophytes, rarely
rheophytes, streams, marshes.
NOTES: L. nairii and L. gomezii are quite distinct from the
other species.
ETYMOLOGY: Greek lagenos or lagynos (flask, bottle) and
anêr, andros (man).
TAXONOMIC ACCOUNTS: Engler (1920a), de Wit
(1978,1990), Sivadasan (1982), Bogner & Jacobsen (1987),
Nicolson (1988a), Kasselmann (1995).
C
57. Cryptocoryne
Cryptocoryne Fischer ex Wydler in Linnaea 5: 428 (1830).
TYPE: C. spiralis (Retzius) Fischer ex Wydler (Arum spirale
Retzius).
Laticifers absent in foliage leaves but present in stem, roots and
cataphylls (Sivadasan, pers. comm.). HABIT: small or mediumsized herbs, evergreen or rarely dormant in dry season (C.
nevillii, C. consobrina), rhizome creeping, stoloniferous.
LEAVES: many, cataphylls conspicuous when present. PETIOLE: sheath fairly long. BLADE: ptyxis convolute, cordate,
ovate, lanceolate, elliptic, linear, rarely filiform (seasonally so
in C. retrospiralis), mostly glabrous, rarely pubescent, sometimes bullate; primary lateral veins pinnate, usually weakly
differentiated, running into inconspicuous marginal vein,
higher order venation transverse-reticulate. INFLORESCENCE:
solitary, usually appearing with the leaves (except C. consobrina). PEDUNCLE: short, elongating in fruit. SPATHE: tube
with connate margins, at base swollen into ellipsoid to cylindric “kettle”, kettle rarely constricted, sometimes alveolar
within, entrance with a lateral flap partially or completely covering male zone of spadix, upper part of tube long or short (in
some species length depending on water depth), rarely absent
(C. spiralis), sometimes widening or narrowing at mouth, blade
cordate to lanceolate, erect or reflexed at anthesis, spreading,
slightly twisted or long-spiralled, apex cuspidate to long-caudate, inner surface smooth, rough, uniformly warty or with
warts in transverse bands, or covered with shortly branched
protuberances, white, yellow, red, purple, brown, sometimes
spotted, junction with tube usually marked by inconspicuous
to very prominent “collar” which normally differs in colour and
texture from blade. SPADIX: slender, female zone consisting of
a single basal whorl of 4–8 upright gynoecia, with single whorl
of rounded, subclavate or irregular olfactory bodies (?pistillodes) usually present immediately above, female and male
zones separated by a long naked axis , or rarely fertile zones
almost contiguous, male zone ellipsoid to subcylindric, terminal appendix short, conical or irregularly oblong to subclavate,
apically adnate to spathe behind flap, often breaking free during anthesis. FLOWERS: unisexual, perigone absent. MALE
FLOWER: apparently 1-androus, stamens free, anthers sessile
or with short filaments, apex excavated with very prominent,
thickened margins, connective inconspicuous, thecae opposite,
ending in short to long, attenuate horn usually projecting
beyond thickened margins, dehiscing by apical pore. POLLEN:
extruded in a droplet, inaperturate, ellipsoid to oblong,
medium-sized (mean 34 µm., range 27–42 µm.), exine psilate.
FEMALE FLOWER: ovaries connate, 1-locular, ovules 5 to
many, orthotropous, funicle short, usually bearing numerous
long trichomes extending between ovules, placenta subbasal
to obliquely parietal (adaxial, morphologically basal), stylar
region free, usually curved away from spadix axis, stigma discoid, rounded or elongated, often emarginate, often centrally
concave. FRUIT: not a berry, all connate into an ovoid, smooth
to verrucose syncarp dehiscing apically at maturity and becoming star-shaped. SEED: ellipsoid-oblong, straight or slightly
curved, testa brown, not very thick, rough to slightly costate,
or smooth, embryo elongate, straight, endosperm copious;
seed sometimes viviparous and then seedling with many filiform cataphylls (C. ciliata). See Plates 57, 119B.
CHROMOSOMES: 2n = 20, 22, 28, 30, 33, 34, 36, 42, 54, 66,
68, 72, 85, 88, 90, 102, 132.
DISTRIBUTION: ca. 50 spp.; tropical Asia, Malay
Archipelago:– Bangladesh, Brunei, Burma, Cambodia, China
(Guandong, Guangxi, Guizhou, Yunnan), India, Indonesia
(Borneo, Irian Jaya, Java, Moluccas, Sulawesi, Sumatra), Laos,
Malaysia (Borneo, Peninsula), Papua New Guinea,
Philippines, Singapore, Sri Lanka, Thailand, Vietnam.
ECOLOGY: tropical humid forest, freshwater tidal zone, rarely
in brackish water (C. ciliata), submerged or emergent aquatics, helophytes or facultative rheophytes.
NOTES: Jacobsen (1982) recognized 26 informal subgroups.
C. spiralis is distinguished from other species of the genus in
its spathe, which lacks the tube between kettle and blade and
57. Cryptocoryne
C RY P TO C O RY N E A E : C RY P TO C O RY N E
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26d Tribes & Genera Acro 18/7/97 6:29 Page 198
D
F
E
J
B
G
H
K
A
L
C
M
Plate 57. Cryptocoryne. A, habit × 2/3; B, inflorescence × 1; C, inflorescence with spadix detail viewed through opened kettle × 2; D, stamen × 30; E, female zone of spadix × 6; F, gynoecium, longitudinal section × 6; G, syncarp × 1; H, habit × 2/3; J, inflorescence × 1; K,
inflorescence × 1; L, habit × 2/3; M, syncarp × 1. Cryptocoryne spiralis: A, Sivadasan CU 21406 (K); Sivadasan CU 21435 (K); B–G, Bogner
1829 (Kew spirit collection 53996); C. affinis: H, Bogner 1706 (K); J, Bogner 227 (Kew spirit collection 45235); C. ciliata: K, Cult. Kew 1953–203
(Kew spirit collection 16895); C. longicauda: L, Dransfield s.n. (Kew slide collection); M, Bogner 1735 (Kew spirit collection 50159).
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has a transverse perforated septum at the mouth of the kettle. It thus strongly resembles Lagenandra in this respect.
However, C. spiralis shares with the other species of
Cryptocoryne the connate gynoecia borne in a single whorl,
the syncarpous infructescence and convolute ptyxis.
ETYMOLOGY: Greek kryptos (hidden) and korynê (club);
the spadix is entirely enclosed in the spathe tube and thus
hidden from view.
TAXONOMIC ACCOUNTS: Engler (1920a), Rataj (1975),
Jacobsen (1982, 1985, 1988, 1991), Sivadasan (1982),
Jacobsen & Bogner (1987), Jacobsen, Sivadasan & Bogner
(1989), de Wit (1990), Kasselmann (1995).
C
Tribe Zomicarpeae
Tribe Zomicarpeae Schott, Syn. Aroid. 33 (1856).
Laticifers anastomosing; small, evergreen (Ulearum) or seasonally dormant (Zomicarpa, Zomicarpella); leaf blade
cordate-sagittate (except Zomicarpa); primary lateral veins
often arising at petiole insertion, higher order venation reticulate; spadix longer than spathe (except Zomicarpa,
Zomicarpella amazonica), with sterile terminal appendix,
female spadix zone adnate to spathe; flowers unisexual,
perigone absent; stamens free; gynoecia few, ovary 1-locular,
ovules anatropous, placenta basal.
C
58. Zomicarpa
Zomicarpa Schott, Syn. Aroid. 33 (1856). TYPE: Z. pythonium (Martius) Schott (Arum pythonium Martius).
HABIT: small, seasonally dormant herbs, tuber subglobose
to depressed-globose. LEAVES: few. PETIOLE: sheath short.
BLADE: entire ovate-cordate when juvenile, adult blade trisect to pedatisect, lobes oblong-elliptic or oblong-lanceolate,
58. Zomicarpa
outer ones smaller; primary lateral veins of lobes pinnate,
joined into submarginal collective vein at least in upper
half of lobe, 1–2 marginal veins also present, higher order
venation reticulate. INFLORESCENCE: 3–5 in each floral
sympodium, appearing before or with leaves. PEDUNCLE:
longer than petiole, slender. SPATHE: somewhat constricted,
entirely persistent, tube only laxly convolute, slightly gaping at anthesis, obliquely held, blade longer than tube,
expanded at anthesis, distinctly or slightly bent forward at
constriction, ± erect, sometimes fornicate, ovate-lanceolate
or lanceolate, acuminate. SPADIX: shorter than spathe,
female zone few- and laxly flowered, adnate to spathe,
contiguous with male zone, male zone cylindric, longer
than female, laxly to densely flowered, appendix erect or
bent forward near base, clavate to subcylindric, smooth or
± covered with sterile flowers (Z. steigeriana). FLOWERS:
unisexual, perigone absent. MALE FLOWER: 1–2-androus,
stamens free, filaments distinct or very short, connective distinctively coloured, thecae ellipsoid, opposite, dehiscing by
apical pore. POLLEN: inaperturate, spherical to subspheroidal, medium-sized (mean 32 µm., range 32–33 µm.), exine
spinose. STERILE FLOWERS: sparse when present, conic
and acuminate towards base of appendix, otherwise wartlike. FEMALE FLOWER: gynoecium cylindric or ovoid to
subglobose, ovary 1-locular, ovules 6–11, anatropous, funicle distinct, placenta basal, stylar region shortly attenuate,
stigma broad, discoid-hemispheric. BERRY: globose to
depressed-globose, whitish below, darker at apex, few–several-seeded. SEED: ovoid to ellipsoid, testa smooth, thin,
transparent, micropyle shortly rostrate, funicle strophiolate,
swollen, white, embryo axile, elongate, endosperm copious.
See Plates 58, 119C.
CHROMOSOMES: 2n = 20.
DISTRIBUTION: 3 spp.; Brazil (Northeast).
ECOLOGY: tropical humid forest, upland gallery forest,
deciduous forest; geophytes on forest floor.
ETYMOLOGY: Greek zômê (woman’s girdle) and karpos
(fruit); refers to spathe constriction.
TAXONOMIC ACCOUNTS: Peyritsch (1879), Engler (1920a),
Bogner (1980d).
C
59. Zomicarpella
Zomicarpella N.E. Brown in Gard. Chron., ser.2, 16: 266
(1881). TYPE: Z. maculata N.E. Brown
HABIT: small herbs with creeping rhizome. LEAVES: 1–3.
PETIOLE: sheath short. BLADE: cordate-sagittate to hastatesagittate, often variegated with pale green blotches; primary
lateral veins mostly arising at petiole insertion, running into
margin or forming a submarginal collective vein, higher order
venation reticulate. INFLORESCENCE: 1–2 in each floral sympodium, appearing with leaves. PEDUNCLE: slender, longer
or shorter than petiole. SPATHE: oblong-lanceolate, fully
expanded and unconstricted (Z. maculata), or constricted
between tube and blade, tube convolute, blade expanded,
erect at first, then reflexed, persistent in fruit (Z. amazonica).
SPADIX: longer or shorter than spathe, female zone adnate
to spathe, contiguous or separated from male by short axis
(Z. maculata), male zone subequal to female, cylindric, terminal appendix more slender, ± elongate. FLOWERS:
unisexual, perigone absent. MALE FLOWER: 1-androus, stamens densely arranged, free, anthers subsessile, filaments
short but distinct, connective inconspicuous, thecae opposite,
ZOMICARPEAE : ZOMICARPELLA
199
26d Tribes & Genera Acro 18/7/97 6:30 Page 200
B
C
E
F
A
G
D
Plate 58. Zomicarpa. A, habit with mature leaf × 1; B, juvenile leaf × 1; C, semi–mature leaf × 1; D, spadix × 5; E, stamen × 20; F, gynoecium, longitudinal section × 20; G, infructescence, nearside half of spathe removed × 2. Zomicarpa riedeliana: A, Noblick, Lemos & Valdomiro
3202 (K); B, Cult. Berkley (K); C, Mayo s.n. (K); D–F, Bogner 1213 (Kew spirit collection 42464); G, Schott, Icones Aroideae 3760 (K).
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26d Tribes & Genera Acro 18/7/97 6:30 Page 201
A
B
D
F
H
G
M
C
L
J
K
E
Plate 59. Zomicarpella. A, leaf × 1; B, inflorescence, nearside half of spathe folded back × 3; C, habit × 1; D, leaf × 1; E, inflorescence,
nearside half and upper part of spathe removed × 3; F, stamen, top view × 15; G, stamen, side view × 15; H, stamen, longitudinal section ×
15; J, gynoecium × 15; K, gynoecium, longitudinal section × 15; L, fruit × 3; M, seed × 4. Zomicarpella maculata: A–B, Cult. Linden (K); Z.
amazonica: C–D, Bogner 1985 (K & Kew spirit collection 57529 & 57400); E–M, Bogner 1985 (Kew spirit collection 57529 & 57400).
ZOMICARPEAE : ZOMICARPELLA
201
26d Tribes & Genera Acro 18/7/97 6:30 Page 202
59. Zomicarpella
subglobose, dehiscing by apical pore. POLLEN: extruded in
strands, inaperturate, spherical, small (18–20 µm. diam.), exine
spinose. FEMALE FLOWER: gynoecium ellipsoid-oblong, or
depressed-bottle-shaped, somewhat laterally compressed,
ovary 1-locular, ovules 1–6, anatropous, funicle short or very
short, placenta basal, stylar region short, distinct, narrower
than ovary, stigma small, discoid-hemispheric. BERRY:
depressed-globose, whitish, stigma remnant persistent, 1–3seeded. SEED: irregularly ellipsoid, somewhat compressed
laterally, testa thin, smooth, whitish, raphe conspicuous, hilum
somewhat sunken, purple, embryo ellipsoid to pear-shaped,
small, endosperm copious. See Plates 59, 119D.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: 2 spp.; Brazil (western Amazonia),
?Colombia.
ECOLOGY: tropical humid forest (“terra firme”); geophytes
on forest floor.
NOTES: Zomicarpella maculata N.E. Br. was described from
a cultivated plant known to have originated in tropical
America, but without a more exact provenance. No other collection of this species has been seen.
ETYMOLOGY: Zomicarpa and Latin -ella (diminutive); refers
to similarity to Zomicarpa.
TAXONOMIC ACCOUNTS: Engler (1920a), Bogner (1979a),
Bogner (in press).
C
insertion, forming a submarginal collective vein, 1–2 marginal veins also present, higher order venation reticulate.
INFLORESCENCE: solitary. PEDUNCLE: slender, subequal
to or longer than petiole, base enclosed by a single relatively long cataphyll. SPATHE: oblong-lanceolate, greenish,
unconstricted, completely expanded, margins revolute, persistent and dark green in fruit. SPADIX: slender, subequal
to spathe, female zone adnate to spathe, separated from
male zone by a longer sterile zone, lower part of sterile
zone naked or only sparsely covered with sterile flowers,
upper part with short dense zone of staminodes, male zone
short, composed of 6–7 whorls of stamens, terminal appendix digitiform, base composed of a few whorls of apically
rounded staminodes, becoming smooth above. FLOWERS:
unisexual, perigone absent. MALE FLOWER: apparently 1androus, stamens sessile, free, subtruncate, connective ±
broad, thecae ellipsoid to globose, dehiscing by apical
pore. POLLEN: inaperturate, spherical, medium-sized
(diam. 26–32 µm.), exine spinose. STERILE FLOWERS:
depressed globose or cylindric; staminodes below male
zone in 2–3 whorls, rounded apically. FEMALE FLOWER:
gynoecium narrowly subcylindric, ovary 1-locular, ovule 1,
anatropous, funicle short, placenta basal, stylar region ± as
thick as ovary, stigma discoid, as broad as style. BERRY:
subcylindric to ellipsoid, stigmatic remnant persistent, 1seeded, dark green and red-spotted. SEED: ellipsoid, testa
thin, white, smooth, transparent, embryo ellipsoid, dark
green with red spots externally, whitish internally, undifferentiated, endosperm absent. See Plates 60, 120A.
CHROMOSOMES: 2n = 14.
DISTRIBUTION: 1 sp.; Brazil (western Amazonia), Peru
(Amazonia).
ECOLOGY: tropical humid forest (“terra firme”); geophytes
on forest floor.
ETYMOLOGY: named after Ernst Ule (1854–1915) and Arum.
TAXONOMIC ACCOUNTS: Engler (1920a), Boyce (1995e).
60. Ulearum
Ulearum Engler in Bot. Jahrb. 37: 95 (1905, “1906”). TYPE:
U. sagittatum Engler
HABIT: small evergreen herb, rhizome creeping horizontally just below the soil surface. LEAVES: 1–several, 1
marcescent cataphyll enclosing base of petiole. PETIOLE:
sheath very short. BLADE: subreniform to broadly sagittate,
often variegated; primary lateral veins arising from petiole
202
THE GENERA OF ARACEAE
60. Ulearum
26d Tribes & Genera Acro 18/7/97 6:31 Page 203
F
E
C
D
B
A
Plate 60. Ulearum. A, habit × 2/3; B, inflorescence, nearside half of spathe removed × 3; C, gynoecium × 20; D, gynoecium, longitudinal
section × 20; E, staminode × 20; F, stamen, side view × 10. Ulearum sagittatum: A, Ule 6323 (K); B, Jangoux et al. INPA 138864 (Kew spirit
collection 56426); C–F, Bogner 1947 (K & Kew spirit collection 56424).
ZOMICARPEAE : ULEARUM
203
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C
61. Filarum
Filarum Nicolson in Brittonia 18: 348 (1967). TYPE: F.
manserichense Nicolson (“manserichensis”).
Tribe Caladieae Schott in Schott & Endlicher, Melet. Bot. 18
(1832).
HABIT: small herb, tuber subglobose. LEAVES: few. PETIOLE: sheath short. BLADE: entire, cordate; primary lateral
veins 3 per side, arising from petiole insertion, lower 2
pairs retrorse, all arcuately curving upwards forming submarginal collective vein, marginal vein distinct, higher order
venation reticulate. INFLORESCENCE: 1–3 in each floral
sympodium, appearing with leaves. PEDUNCLE: slender,
longer or shorter than petiole. SPATHE: persistent, oblonglanceolate, pale green. SPADIX: very slender, much longer
than spathe, female zone adnate to spathe, few-flowered,
separated from male zone by longer sterile zone, male zone
elongate, purple, sparsely flowered, with a very few sterile
rudimentary flowers occurring above and below male zone,
appendix slender, naked, elongate. FLOWERS: unisexual,
perigone absent. MALE FLOWER: 1-androus, filaments
short, connective extremely long and drawn out into a filiform flexuose thread, thecae globose, dehiscing by apical
pore. POLLEN: inaperturate, spherical, small to mediumsized (mean 21 µm.), exine spinose. FEMALE FLOWER:
ovary oblong, 1-locular, ovule 1, anatropous, funicle short,
placenta basal, stylar region attenuate, stigma small, discoid. BERRY: ellipsoid, smooth, bearing the style and stigma
remains. SEED: ellipsoid, testa thin, smooth, punctate,
embryo ellipsoid, endosperm absent. See Plate 61.
CHROMOSOMES: 2n = 28.
DISTRIBUTION: 1 sp.; Peru (Amazonia).
ECOLOGY: tropical humid forest; geophytes on forest floor.
ETYMOLOGY: Latin filum (thread) and Arum; named after
the thread-like spadix and stamen connectives.
Laticifers anastomosing; terrestrial, geophytic, rarely aquatic
(Jasarum) or climbing hemiepiphytes (Syngonium), stem
tuberous, rhizomatous or aerial; basal ribs well-developed,
primary lateral veins of leaf pinnate, forming submarginal
collective vein, 1 or more marginal veins also usually present, higher order venation reticulate; spadix: female zone
often separated from male by subconical to attenuate zone
of synandrodes (sterile male flowers), male zone subcylindric to subclavate, sterile appendix absent (except
some Hapaline); flowers unisexual, perigone absent; stamens connate into synandria, synandria truncate, margins
sinuous, thecae dehiscing by short apical slit, pollen
extruded in strands (except Scaphispatha); ovules anatropous to hemianatropous; endosperm copious (except
Jasarum, Syngonium, Hapaline).
61. Filarum
204
Tribe Caladieae
THE GENERA OF ARACEAE
62. Scaphispatha
Scaphispatha Brongniart ex Schott, Prodr. syst. Aroid. 214
(1860). TYPE: S. gracilis Brongniart ex Schott
HABIT: seasonally dormant herb, tuber globose to depressed-globose. LEAVES: usually solitary, sometimes 2.
PETIOLE: slender, sheath very short. BLADE: ovate-subcordate to ovate-sagittate, peltate, apex cuspidateacuminate; basal ribs well-developed, primary lateral veins
pinnate, forming submarginal collective vein, 1–2 marginal
veins also present, higher order venation reticulate. INFLO-
62. Scaphispatha
C
C
26d Tribes & Genera Acro 18/7/97 6:31 Page 205
E
B
D
F
G
A
H
C
Plate 61. Filarum. A, habit × 1; B, leaf × 1; C, inflorescence, nearside spathe base folded back × 4; D, stamen, side view × 16; E, stamen,
view from below × 16; F, gynoecium × 16; G, gynoecium, longitudinal section × 16; H, fruit × 10. Filarum manserichense A, D–G, Wurdack
2402 (K); B–C, H, Mexia 6353 (K).
ZOMICARPEAE : FILARUM
205
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H
E
F
D
B
C
G
A
Plate 62. Scaphispatha. A, habit × 1; B–C, inflorescences × 1; D, spadix × 5; E, synandrium, top view × 30; F, synandrium, side view
× 30; G, gynoecium, longitudinal section × 30; H, infructescence × 1. Scaphispatha gracilis: A–C, Hatschbach & Koczicki 33081 (K); D–H,
Bogner 1211 (Kew spirit collection 42451).
206
THE GENERA OF ARACEAE
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RESCENCE: solitary, appearing well before leaf. PEDUNCLE:
very long, slender. SPATHE: decurrent on peduncle, slightly
constricted between tube and blade, light green without,
white within, tube convolute before and after anthesis, gaping at anthesis, persistent to fruiting stage, blade fully
expanded at anthesis, at first erect, later reflexed, marcescent after anthesis. SPADIX: sessile, cylindric, hardly
constricted, shorter than spathe, fertile to apex, densely
flowered, male and female zones contiguous. FLOWERS:
unisexual, perigone absent. MALE FLOWER: 4-androus, stamens connate into truncate, deeply lobed synandrium,
connective not greatly thickened, thecae lateral, dehiscing
apically by broad, pore-like slit. POLLEN: inaperturate,
spherical to subspheroidal, medium-sized (mean 45 µm.),
exine coarsely verrucate with large polygonal flat-topped
verrucae. FEMALE FLOWER: ovary ovoid, 1-locular, ovules
3–5, anatropous, funicle short, placenta basal, stylar region
distinct, attenuate, much narrower than ovary, stigma small,
discoid-subcapitate, only slightly broader than style. BERRY:
subglobose to obovoid, always 1-seeded, stigma remnants
persistent, fruiting very rapidly (ca.10 days after anthesis),
whitish-grey. SEED: subglobose, testa smooth and thin,
greyish to brown, covered with minute brownish spots,
raphe pronounced, swollen, embryo elongate, straight,
endosperm copious. See Plates 62, 120B.
CHROMOSOMES: 2n = 28.
DISTRIBUTION: 1 sp.; Bolivia, Brazil (southern Amazonia,
Central West, Northeast).
ECOLOGY: tropical seasonal and dry forest, open woodland; geophytes, temporarily wet places, flowering at
beginning of rainy season after first rains.
ETYMOLOGY: Greek skaphê (boat, bowl) and -ion (diminutive) and “spathê” (spathe); refers to spathe shape.
TAXONOMIC ACCOUNTS: Engler (1920a), Bogner (1980d).
C
63. Caladium
Caladium Ventenat, Descript. Pl. Nouv. Jard. Cels, 30 (1801).
LECTOTYPE: C. bicolor (Aiton) Ventenat (Arum bicolor Aiton,
see Hubbard & Rehder, Bot. Mus. Leafl. 1: 3. 1932).
SYNONYMS: Phyllotaenium André in Ill. Hort. 19: 3
(1872); Aphyllarum S. Moore in Trans. Linn. Soc. London,
Bot. ser. 2, 4: 501 (1895).
HABIT: seasonally dormant or evergreen herbs, stem tuberous, subglobose. LEAVES: several. PETIOLE: sheath distinct.
BLADE: usually peltate, sometimes not (C. lindenii), often
variegated, cordate-sagittate or sagittate, rarely trisect (C. ternatum); basal ribs well-developed, primary lateral veins
pinnate, forming submarginal collective vein, 1–2 marginal
veins also present, secondary and tertiary laterals arising
from the primaries at a wide angle, forming interprimary collective vein, higher order venation reticulate.
INFLORESCENCE: 1–2 in each floral sympodium, appearing
with or before leaves. PEDUNCLE: rather long, often as long
as petiole. SPATHE: constricted, tube with convolute margins,
usually ventricose-globose, persistent, green, eventually splitting in fruit, blade white, boat-shaped, gaping, marcescent
after anthesis and deciduous. SPADIX: a little shorter than
spathe, stipitate or sessile, densely flowered, female zone
cylindric-conoid or ellipsoid, separated from male by longer,
subconic to attenuate, basally thicker zone of sterile male
flowers, male zone fertile to apex, subcylindric to subclavate,
63. Caladium
more than twice as long as female zone. FLOWERS: unisexual, perigone absent. MALE FLOWER: 3–5-androus, stamens
connate into obpyramidal, truncate to ± convex, sinuously
subhexagonal synandrium, common connective thick, thecae
lateral, extending nearly to base of synandrium, oblonglanceolate, dehiscing by short apical slit. POLLEN: extruded
in strands, shed in monads, inaperturate, spherical to subspheroidal, medium-sized (mean 41 µm., range 38–43 µm.),
exine psilate or obscurely dimpled or verruculate. STERILE
MALE FLOWERS: synandrodes depressed-obpyramidal, compressed, truncate, lowermost often larger and prismatic,
uppermost narrow and elongated. FEMALE FLOWER: gynoecium cylindric to obconic, ovary 1–2(–3)-locular, ovules 1–20,
anatropous, funicle short, placentae subbasal, pseudoaxile or
parietal, stylar region free or rarely coherent (C. paradoxum),
as broad as ovary or broader in obconic gynoecia, stigma
nearly as wide as ovary. BERRY: 1–many-seeded (C. ternatum usually 1-seeded), white. SEED: ovoid to ellipsoid, raphe
somewhat prominent, integument succulent, testa thick, longitudinally costate, costae angled, embryo axile, elongate,
endosperm copious. See Plates 63, 120C.
CHROMOSOMES: 2n = 22, 26, 28, 30, 32.
DISTRIBUTION: ca. 12 spp.; tropical America, West Indies:–
N. Argentina, Bolivia, Brazil, Colombia, Costa Rica, Ecuador,
French Guiana, Guyana, Lesser Antilles, Panama, Peru, Puerto
Rico, Surinam, Venezuela.
ECOLOGY: tropical humid forest, open woodlands; geophytes, forest floor, river margins and damp sites.
NOTES: Caladium bicolor and its many cultivated varieties
are cultivated throughout the world as ornamental plants.
This species occurs throughout tropical America.
ETYMOLOGY: Latinization of Malay word keladi, a vernacular name in Malaysia for several colocasioid genera.
CALADIEAE : CALADIUM
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S
B
N
J
Q
R
P
M
A
D
G
E
L
H
F
K
C
Plate 63. Caladium. A, leaf × 1/3; B, base of plant × 1/2; C, spadix × 1; D, synandrium × 10; E, upper synandrode × 5; F, lower synandrode
× 5; G, gynoecium × 10; H, gynoecium, transverse section × 10; J, infructescence × 2/3; K, leaf × 1/3; L, spadix × 1; M, inflorescence × 2/3; N,
synandrium × 10; P, synandrode × 10; Q, gynoecium × 10; R, gynoecium, longitudinal section × 10; S, habit × 1/5. Caladium aristeguietae:
A–B, Bunting 2201 (K); C–H, Bunting 2201 (Kew spirit collection 58022); J, Bunting 4521 (K); C. coerulescens: K, Bunting 4980 (K); L, Bunting
4865 (K); C. lindenii: M–R, Cult. Kew 1982–02775 (Kew spirit collection 39521); C. bicolor: S, Lowe 3.1962, 7220 (Kew slide collection).
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THE GENERA OF ARACEAE
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TAXONOMIC ACCOUNTS: Engler in Engler & Krause (1920),
Madison (1976b, 1981), Bogner (1984d), Grayum (1986c),
Mayo & Bogner (1988).
C
64. Jasarum
Jasarum Bunting in Acta Bot. Venezuelica 10: 264 (1977,
“1975”). TYPE: J. steyermarkii Bunting
HABIT: evergreen aquatic herb, stem thick, hypogeal,
upright, annulate, terete, surface brown, white within, usually unbranched, roots thick, somewhat spongy. LEAVES:
6–12, dark green in all parts except whitish hypogeal lower
part of petiole. PETIOLE: sheath long, fleshy. BLADE: linear, somewhat bullate, acute to cuspidate, cuneate at base,
midrib pronounced; primary lateral veins pinnate, numerous, 35–60 per side, joined into submarginal collective
vein, marginal vein also present, higher order venation
reticulate. INFLORESCENCE: solitary, held above water
level. PEDUNCLE: much longer than petiole. SPATHE: erect,
constricted between tube and blade, tube convolute, persistent, blade long-acuminate, never reflexed, marcescent
after anthesis and later deciduous, bronze-green outside,
cream-coloured within. SPADIX: shorter than spathe, subcylindric, basal half of female zone adnate to spathe,
separated from male by zone of sterile flowers (synandrodes), male zone fertile to apex. FLOWERS: unisexual,
perigone absent. MALE FLOWER: 3–4-androus, stamens
connate into synandrium, synandrium truncate, irregularly
4–6-angled, thecae 6–8, lateral, elongate, dehiscing by apical pore. POLLEN: ellipsoid, medium-sized (mean 44 µm.),
64. Jasarum
exine foveolate-reticulate. FEMALE FLOWER: ovary cylindric, 1-locular, ovules (1–)2–3(–4), anatropous, funicle
distinct, placenta basal, stylar region broader than ovary,
stigma discoid-hemispheric. BERRY: subovoid, tightly
packed, dull maroon- green apically, stigma remains persistent, pericarp fleshy, usually 1-seeded, sometimes
2-seeded. SEED: large, obovoid, compressed when paired,
testa smooth, embryo globular, large, green, plumule welldeveloped, raphe prominent, endosperm nearly absent.
See Plates 64, 120D.
CHROMOSOMES: 2n = 22.
DISTRIBUTION: 1 sp.; tropical South America: Venezuela,
Guyana.
ECOLOGY: tropical uplands; submerged aquatic in oligotrophic (blackwater) streams.
ETYMOLOGY: named after Julian A. Steyermark (1909–1988).
TAXONOMIC ACCOUNTS: Bunting (1977), Bogner (1985b).
C
65. Xanthosoma
Xanthosoma Schott in Schott & Endlicher, Melet. Bot. 19
(1832). LECTOTYPE: X. sagittifolium (L.) Schott (“sagittaefolium”; Arum sagittaefolium L.; see Nicolson 1975).
SYNONYMS: Acontias Schott in Schott & Endlicher, Melet.
Bot. 19 (1832); Cyrtospadix K. Koch in Index Sem. Hort.
Berol. 1853 App.: 13 (1853).
Latex milky. HABIT: small to gigantic, sometimes arborescent, evergreen or seasonally dormant herbs, stem either a
thick, subcylindric, hypogeal tuber often producing smaller
tubers on stoloniferous side branches or often with a distal, epigeal, massive, arborescent upper part, or an entirely
hypogeal subglobose tuber, bearing many very small tubercles in some spp. (X. pubescens, X. viviparum), tuber
sometimes yellow within. LEAVES: several, rarely pubescent. PETIOLE: sheath usually rather long. BLADE: cordate,
sagittate, hastate, trifid, trisect, pedatifid or pedatisect, rarely
linear-lanceolate to ovate with emarginate base, rarely
peltate; basal ribs well-developed, often denuded proximally, primary lateral veins pinnate, forming submarginal
collective vein, 1 or more distinct marginal veins also present, secondary and tertiary laterals arising from the
primaries at a wide angle, forming interprimary collective
vein, higher order venation reticulate. INFLORESCENCE: 1
to many in each floral sympodium, always appearing with
leaves. PEDUNCLE: usually rather short, rarely long.
SPATHE: strongly constricted, tube with convolute margins,
ovoid to ellipsoid, usually ventricose, rather thick-walled in
large species, persistent, blade boat-shaped-oblong to oblong-lanceolate, gaping and erect or sometimes reflexed
at anthesis, marcescent after anthesis and then deciduous.
SPADIX: shorter than spathe, densely flowered, female zone
cylindric-conoid, often obliquely inserted onto peduncle,
separated from male zone by longer, conoid to attenuate,
basally thicker zone of sterile male flowers, male zone cylindric-conoid, longer than female zone, usually fertile to apex,
rarely with a few sterile flowers at extreme apex. FLOWERS:
unisexual, perigone absent. MALE FLOWER: 4–6-androus,
stamens connate into a truncate-obpyramidal, subpentagonal or hexagonal synandrium, anthers lateral, nearly
reaching base of synandrium, common connective thick,
thecae oblong or tapering basally, dehiscing by subapical
pore or short slit. POLLEN: extruded in strands, shed in
CALADIEAE : XANTHOSOMA
209
26d Tribes & Genera Acro 18/7/97 6:33 Page 210
J
B
H
E
G
F
A
D
C
Plate 64. Jasarum. A, habit, peduncle partly removed × 1/2; B, detail of leaf venation × 2/3; C, inflorescence × 2/3; D, spadix × 2; E, synandrium, side view × 15; F, gynoecium × 15; G, gynoecium, longitudinal section × 15; H, infructescence × 2/3; J, berry, side view × 2. Jasarum
steyermarkii: A, Bunting 4628 (K); Herkner & Jeschke s.n. (Kew spirit collection 29047.618); Aroideana 8(2): 55–63, f.4 (1985); B–J, Cult.
Munich (Kew spirit collection 57524); Herkner & Jeschke s.n. (Kew spirit collection 29047.618).
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THE GENERA OF ARACEAE
26d Tribes & Genera Acro 18/7/97 6:33 Page 211
tetrads, inaperturate, ellipsoid to subspherical, mediumsized (mean 42 µm., range 35–49 µm., tetrads:– mean 76
µm., range 62–97 µm.), exine minutely punctate- or fossulate-verruculate. STERILE MALE FLOWER: composed of
obpyramidal truncate, laterally compressed synandrodes,
lowermost larger, uppermost narrower and more elongated
(in sense of spadix axis). FEMALE FLOWER: ovary ovoid,
2–4-locular, more rarely 1-locular, ovules (12–)20 to very
numerous, anatropous or hemianatropous, funicles rather
long, placentae usually pseudoaxile, or sometimes parietal
or axile basally, stylar region broader than ovary, usually
discoid-thickened and coherent to weakly connate with
those of neighbouring flowers, rarely free and swollen (X.
plowmanii), stigma subhemispheric or 2–4-lobed, yellow,
narrower than style. BERRY: cylindric, somewhat furrowed
apically, whitish to orange, many-seeded. SEED: ovoid,
testa costate, embryo axile, subequal to endosperm,
endosperm copious. See Plates 65, 121A.
CHROMOSOMES: 2n = 22, 26, 39, 52.
DISTRIBUTION: ca. 57 spp.; tropical and southern subtropical America, West Indies:– N. Argentina, Bolivia, Brazil,
Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador,
El Salvador, French Guiana, Guatemala, Guyana, Haiti,
Honduras, Jamaica, Lesser Antilles, Mexico, Nicaragua,
Panama, Paraguay, Peru, Puerto Rico, Surinam, Trinidad,
Venezuela.
ECOLOGY: tropical moist and humid forest, subtropical forest; geophytes on forest floor, in wet places, swamps, river
banks, seasonally flooded sites, grassy places, plantations,
some species are weedy.
NOTES: Engler in Engler & Krause (1920) recognized 2 sections:– section Xanthosoma, section Acontias.
65. Xanthosoma
VERNACULAR NAMES AND USES: “cocoyam”, “tannia”; X.
sagittifolium and its many varieties are important subsistence food plants throughout the humid tropics of the world
due to their starch- and protein-rich tuberous stems (see
chapter 16).
ETYMOLOGY: Greek “xanthos” (yellow) and “soma,
somatos” (body); refers to the yellow colour of the stem tissue present in several species.
TAXONOMIC ACCOUNTS: Engler in Engler & Krause (1920),
Madison (1976b, 1981), Bogner (1986b), Grayum (1986c),
Mayo & Bogner (1988), Okeke (1992).
C
66. Chlorospatha
Chlorospatha Engler in Gartenflora 27: 97 (1878). TYPE: C.
kolbii Engler
SYNONYM: Caladiopsis Engler in Bot. Jahrb. 37: 139
(1905).
Latex milky. HABIT: small to medium, usually evergreen
herbs, stem epigeal to ± subterranean, acaulescent to elongate, decumbent to erect. LEAVES: 1 to several. PETIOLE:
sheath long. BLADE: cordate, sagittate, hastate, trifid, trisect, pedatifid or pedatisect; basal ribs well-developed,
primary lateral veins pinnate, forming submarginal collective
vein, 1 or more distinct marginal veins also present, secondary and tertiary laterals arising from the primaries at a
wide angle, forming interprimary collective vein, higher
order venation reticulate. INFLORESCENCE: 3–8 in each floral sympodium. PEDUNCLE: very slender, much shorter than
petiole and supported by sheath. SPATHE: constricted, tube
66. Chlorospatha
CALADIEAE : CHLOROSPATHA
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C
H
J
K
P
A
Q
R
S
F
D
N
E
B
M
L
G
Plate 65. Xanthosoma. A, leaf × 1/4; B, base of plant × 1/5; C, inflorescence × 1/5; D, detail of synandria, top view × 5; E, detail of gynoecia, top view × 5; F, synandrium, side view × 5; G, gynoecia, left hand gynoecium in longitudinal section × 5; H, infructescence × 1/4; J, leaf
× 1/3; K, leaf × 1/2; L, inflorescence, nearside half of spathe removed × 2/3; M, detail of synandrodes, top view × 15; N, synandrode, side
view × 15; P, synandrium, side view × 15; Q, gynoecium × 15; R, gynoecium, longitudinal section × 15; S, ovules × 25. Xanthosoma violaceum:
A–B, Engler 245 (K); C, Vollesen (Kew slide collection); D–H, Skvortzov (Kew spirit collection 29047.189); X. striatipes: J, Krapovickas &
Cristóbal 35351 (K); X. helleborifolium: K, Broadway 6340 (K); X. plowmanii: L–S, Plowman et al. 8460 (Kew spirit collection 49708).
212
THE GENERA OF ARACEAE
26d Tribes & Genera Acro 18/7/97 6:34 Page 213
K
C
E
D
J
F
B
M
L
A
G
H
Plate 66. Chlorospatha. A, habit × 1/2; B, spadix × 2; C, synandrium, side view × 15; D, synandrode, side view × 15; E, gynoecium, side
view × 15; F, gynoecium, longitudinal section × 15; G, leaf × 1/4; H, inflorescences with associated leaf × 1/2; J, inflorescence × 2; K, gynoecium, longitudinal section × 15. L, spadix × 2; M, gynoecium, side view × 15. Chlorospatha longipoda: A, Plowman 14063 (K); B–F, Plowman
3979 (Kew spirit collection 49717); C. croatiana subsp. enneaphylla: G, Lawrence 794 (K); C. atropurpurea: H, Dodson 5911 (K); C. corrugata: J–K, Spear s.n. (Kew spirit collection 42452); C. kolbii : L–M, Franke s.n. (Kew spirit collection 62897).
CALADIEAE : CHLOROSPATHA
213
26d Tribes & Genera Acro 18/7/97 6:34 Page 214
with convolute margins, narrow, elongate, ± cylindric to
narrowly ellipsoid, persistent, blade boat-shaped to more
widely expanded, sometimes fornicate, rather narrowly elliptic to lanceolate, marcescent after anthesis and deciduous.
SPADIX: female zone free or adnate to spathe, laxly or
densely flowered, separated from male zone by longer or
shorter laxly or densely flowered sterile zone, male zone
densely flowered, fertile to apex. FLOWERS: unisexual,
perigone absent. MALE FLOWER: 3–5-androus, stamens connate into truncate synandrium, deeply or shallowly-lobed,
fused connectives thickened, thecae extending almost to
base of synandrium, oblong, dehiscing by short longitudinal
slit. POLLEN: extruded in strands, shed in tetrads, inaperturate, spherical or subspheroidal, medium-sized (mean 26
µm., range 24–29 µm., tetrad mean 45 µm., range 41–48
µm.), exine psilate or very obscurely punctate to obscurely
verruculate to foveolate-reticulate. STERILE FLOWERS: staminodes either free or partially or completely connate into
irregular, fungiform or 3–4 lobed synandrodes, rarely prismatic. FEMALE FLOWER: gynoecium ± ovoid to
subhemispheric, ovary (1–)2–4(–5)- locular, ovules several
per locule, anatropous to hemianatropous, funicle rather
long, placentae pseudoaxile or axile, rarely basal (C.
longipoda), stylar region short to relatively long, usually
expanded into thin, spreading, evanescent mantle contiguous with neighbouring ones, usually containing numerous
red chromoplasts, more rarely style with only a short, rimlike lateral outgrowth (C. longipoda, C. mirabilis) or with soft
tuberculate outgrowth (C. kolbii), stigma subhemispheric or
subcapitate or slightly lobed. BERRY: depressed-globose,
somewhat 3–5-furrowed, stigma remnant persistent, manyseeded, white to yellowish. SEED: minute, ovoid to ellipsoid,
white, testa longitudinally costate, embryo elongate, axile,
endosperm copious. See Plates 66, 121B.
CHROMOSOMES: 2n = 26.
DISTRIBUTION: ca. 16 spp.; tropical America:– Colombia,
Costa Rica, Ecuador, Panama, Peru.
ECOLOGY: tropical humid forest; terrestrial on forest floor,
well shaded creek beds or in boggy areas.
NOTES: Phylogenetically, Chlorospatha may be a derived
offshoot of Xanthosoma, and C. longipoda is somewhat intermediate between the two genera.
ETYMOLOGY: Greek chlôros (green) and spathê (spathe).
TAXONOMIC ACCOUNTS: Engler in Engler & Krause (1920),
Madison (1981), Bogner (1985a), Grayum (1986c, 1991a),
Mayo & Bogner (1988).
C
67. Syngonium
Syngonium Schott in Wiener Z. Kunst 1829 (3): 780 (1829).
TYPE: S. auritum (L.) Schott (Arum auritum L.).
SYNONYM: Porphyrospatha Engler in A. & C. de Candolle,
Monogr. Phan. 2: 289 (1879).
Latex milky. HABIT: root-climbing or shortly creeping, evergreen herbs, internodes short to elongate, green. LEAVES:
numerous. PETIOLE: sheath long. BLADE: at maturity cordate, oblong-cordate, lanceolate, sagittate, trifid to trisect,
pedatifid to pedatisect, rarely pinnatifid, when juvenile
entire, ovate to sagittate or cordate-sagittate or hastate; basal
ribs usually well-developed, primary lateral veins pinnate,
usually forming a submarginal collective vein, 1–2 distinct
marginal veins also present, or sometimes primaries long-
214
THE GENERA OF ARACEAE
67. Syngonium
arcuate and running into margin (e.g. S. schottianum), secondary laterals ± parallel to primaries, higher order venation
reticulate to transverse-reticulate. INFLORESCENCE: 1–8 in
each floral sympodium. PEDUNCLE: much shorter than petiole, erect at anthesis, pendent in fruit. SPATHE: strongly
constricted between tube and blade, tube convolute, ovoidellipsoid, or cylindric or globose, sometimes ventricose,
persistent, blade usually cream, boat-shaped to expanded
at anthesis, erect to spreading, usually marcescent after
anthesis, later deciduous. SPADIX: sessile, much shorter
than spathe, female zone cylindric to conoid, separated
from male zone by zone of sterile flowers, sterile zone constricted, male zone clavate to cylindric or ellipsoid, longer
than female zone, fertile to apex. FLOWERS: unisexual,
perigone absent. MALE FLOWER: 3–4-androus, stamens
connate into synandrium, synandrium obpyramidal, truncate
to rounded at apex, sometimes prominent above thecae,
often deeply lobed, common connective thick, overtopping
anthers, thecae oblong, dehiscing by apical pore or short
slit. POLLEN: extruded in strands, inaperturate, ellipsoidoblong to spherical or subspheroidal, medium-sized (mean
48 µm., range 34–75 µm.), exine minutely fossulate or verruculate, narrowly rugulate and minutely scabrate, spinose
or tuberculate. STERILE MALE FLOWERS: synandrodes ±
prismatic. FEMALE FLOWER: gynoecia connate, rarely ±
free at anthesis and becoming connate later (S. steyermarkii),
ovary obovoid or oblong-obovoid, (1–)2(–3)-locular, ovules
1(–2) per locule, anatropous, funicle short, placenta axile
near septum base to parietal-basal, stylar region as broad as
ovary and ± truncate or very slightly attenuate, stigma discoid or 2-lobed, rarely globose, discoid-capitate or
cup-shaped, narrower than ovary. BERRIES: connate, forming ovoid to ellipsoid, usually brown, sometimes white,
fleshy syncarp, usually exposed at maturity by opening of
persistent orange, yellow, red or violet spathe tube. SEED:
26d Tribes & Genera Acro 18/7/97 6:34 Page 215
A
L
D
M
B
J
C
H
K
F
E
G
Plate 67. Syngonium. A, leaf × 1/3; B, inflorescence × 1/2; C, habit × 1/2; D, infructescences and associated stem × 1/2; E, leaf × 1/3; F,
inflorescence × 1/2; G, leaf × 1/3; H, spadix × 1; J, synandrium, side view × 8; K, detail of gynoecia, top view × 4; L, gynoecium, longitudinal section × 6; M, gynoecium, transverse section × 6. Syngonium steyermarkii: A, 201/12 (Kew slide collection); B, Croat 47201 (Kew spirit
collection 56140); S. armigerum: C, Grayum 6677 (K); S. podophyllum: D, Silverstone-Sopkin et al. 5468 (K); S. neglectum: E–F, Bunting 1658
(K); S. schottianum: G, Cult. Kew June 1878 (K); H–K, Sugden 425 (Kew spirit collection 29047.347); S. vellozianum: L–M, Harley et al. 17874
(Kew spirit collection 46608).
CALADIEAE : SYNGONIUM
215
26d Tribes & Genera Acro 18/7/97 6:35 Page 216
ovoid to ellipsoid, rather large, testa smooth, thin, black or
dark brown, shiny, embryo large, ellipsoid to subglobose,
endosperm absent. See Plates 67, 121C.
CHROMOSOMES: 2n = 28 (24, 26).
DISTRIBUTION: 35 spp.; tropical America, West Indies:–
Belize, Bolivia, Brazil, Colombia, Costa Rica, ?Dominican
Republic, Ecuador, El Salvador, French Guiana, Guatemala,
Guyana, Haiti, Honduras, Jamaica, ?Lesser Antilles, Mexico,
Nicaragua, Panama, Peru, Surinam, Trinidad, Venezuela.
ECOLOGY: tropical humid forest and disturbed areas; climbing epiphytes and hemiepiphytes, creeping when juvenile.
NOTES: Croat (1982) recognizes 4 sections:– sect. Oblongata,
sect. Cordata, sect. Pinnatiloba, sect. Syngonium.
ETYMOLOGY: Greek syn- (together), gonê (womb) and -ion
(diminutive); refers to connate gynoecia.
TAXONOMIC ACCOUNTS: Engler & Krause (1920), Croat
(1982).
C
68. Hapaline
Hapaline Schott, Gen. Aroid. t. 44 (1858), nom. cons. TYPE:
H. benthamiana Schott
SYNONYM: Hapale Schott in Oesterr. bot. Wochenbl. 7:
85 (1857).
HABIT: small to moderate, slender, seasonally dormant or
evergreen herbs, tubers small, depressed-globose. LEAVES:
1–few, usually solitary. PETIOLE: sheath short. BLADE: cordate-sagittate, sagittate or hastate, sometimes pale green or
silvery variegated; primary lateral veins pinnate or mostly
arising at petiole insertion, forming arching submarginal collective vein, 1–2 marginal veins also present, higher order
venation reticulate. INFLORESCENCE: 1–2 in each floral sympodium, appearing with leaf. PEDUNCLE: subequal or longer
than petiole, slender. SPATHE: slender, not distinctly constricted, tube very slender, persistent, tightly convolute around
female flowers, blade longer, oblong-lanceolate, erect to
reflexed and ± revolute at anthesis, marcescent. SPADIX: subequal or longer than spathe, slender, female zone adnate to
spathe, few-flowered (2–7), ± biseriate, separated from male
zone by short sterile zone, male zone subulate to cylindric, fertile to apex or with a few sterile flowers at apex or with a long,
terminal appendix (H. appendiculata). FLOWERS: unisexual,
perigone absent. MALE FLOWER: 3-androus, synandrium
peltate, truncate, hexagonal, elongated in sense of spadix
axis, shallow, stipitate, connective strongly dilated, thecae
short, subglobose, remote, almost pendent from margin,
dehiscing by pore. POLLEN: inaperturate, spherical, mediumsized (mean 40 µm.), exine rather densely spinose. STERILE
FLOWER: lower ones very few, ± remote, apiculiform, upper
ones very few, consisting of tiny, peltate synandrodes.
FEMALE FLOWER: gynoecium oblong to lageniform, ovary 1locular, ovule 1, anatropous, funicle very short, placenta
parietal to subbasal (morphologically basal), stylar region
very short, stigma subcapitate. BERRY: ellipsoid to globose,
style persistent, pericarp thin, 1-seeded, white. SEED: ellipsoid,
testa smooth, very thin, embryo large, ellipsoid, light green,
endosperm absent. See Plates 68, 121D.
CHROMOSOMES: 2n = 26, 28.
DISTRIBUTION: 7 spp.; tropical southeast Asia, Malay
Archipelago:– Brunei, Burma, ?Cambodia, China (Yunnan),
Laos, Malaysia (Borneo, Peninsula), Thailand, Vietnam.
ECOLOGY: tropical humid forest; geophytes on forest floor
or humus deposits on limestone or basalt rocks.
216
THE GENERA OF ARACEAE
68. Hapaline
ETYMOLOGY: modification of the feminine form of Greek
hapalos (soft), referring to the small tender nature of this
genus.
TAXONOMIC ACCOUNTS: Engler in Engler & Krause (1920),
Li (1979), Bogner (1984a), Boyce (1996).
Tribe Nephthytideae
C
Tribe Nephthytideae Engler in Engler & Prantl, Nat.
Pflanzenfam. II (3): 112, 128 (1887).
Laticifers simple, articulated; geophytic, stem tuberous to
rhizomatous; petiole geniculate apically; leaf blade sagittate
or trifid to trisect and highly divided, primary lateral veins
of ultimate lobes or divisions pinnate, higher order venation reticulate; spathe boat-shaped or fully expanded, not
clearly differentiated into tube and blade; spadix cylindric,
female and male zones usually contiguous, sterile flowers
± absent (except Pseudohydrosme); flowers unisexual,
perigone absent; stamens free with filaments lacking or
very short (except Nephthytis); ovules 1 per locule, anatropous, placenta basal (except Pseudohydrosme); berries
and seeds large, testa thin to absent, endosperm absent
(fruit unknown in Pseudohydrosme). Chromosomes large to
very large.
69. Nephthytis
Nephthytis Schott in Oesterr. bot. Wochenbl. 7: 406 (1857).
TYPE: N. afzelii Schott
SYNONYM: Oligogynium Engler in Bot. Jahrb. 4: 64
(1883).
HABIT: evergreen, rarely seasonally dormant, small to
medium-sized herbs, rhizome creeping, subepigeal, rarely
hypogeal, slender to thick, internodes very short, rarely long.
C
26d Tribes & Genera Acro 18/7/97 6:35 Page 217
D
A
C
G
F
E
B
K
H
L
J
Plate 68. Hapaline. A, habit × 2/3; B, leaf × 2/3; C, inflorescence × 2; D, synandrium, top view × 10; E, synandrium, side view × 10; F, gynoecium × 15; G, gynoecium, longitudinal section × 15; H, infructescence × 2; J, habit × 2/3; K, leaf × 2/3; L, leaf × 2/3. Hapaline celatrix: A–H,
Boyce 417 (Kew spirit collection 57283 & Kew slide collection); H. benthamiana: J, Kerr 614 (K); H. ellipticifolia: K, Sun s.n. (YUKU);
H. colaniae: L, Pételot 2919 (K).
CALADIEAE : HAPALINE
217
26d Tribes & Genera Acro 18/7/97 6:35 Page 218
LEAVES: several, rarely solitary. PETIOLE: geniculate apically
(geniculum very long in N. bintuluensis), usually smooth,
rarely sparsely aculeate, uniformly green, sheath very short.
BLADE: cordate-sagittate to sagittate-trifid or subtriangular,
posterior divisions usually longer than anterior, all three divisions often long-acuminate; basal ribs usually
well-developed, primary lateral veins of both anterior and
posterior divisions pinnate forming submarginal collective
vein, higher order venation reticulate. INFLORESCENCE: solitary, usually flowering with leaves, rarely without (N.
bintuluensis). PEDUNCLE: usually relatively slender, shorter
or equalling petiole. SPATHE: ovate- to oblong-elliptic, fully
expanded, spreading to reflexed at anthesis, not constricted,
decurrent on peduncle, green, persistent or marcescent.
SPADIX: short- to long-stipitate, cylindric, female zone contiguous with male, rarely with a few sterile flowers in
between, male zone longer than female, fertile to apex.
FLOWERS: unisexual, perigone absent. MALE FLOWER: 2–4androus, stamens free, obpyramidal, filaments thick, well
developed (except N. hallaei, N. mayombensis), connective
thick, thecae lateral, dehiscing by apical pore. POLLEN: presented in amorphous mass, inaperturate, ellipsoid to
subsphaeroidal, medium-sized (mean 46 µm.), exine verrucate. FEMALE FLOWER: ovary ovoid, 1-locular, ovule 1,
anatropous, funicle very short, placenta basal, stylar region
shortly attenuate or inconspicuous, stigma discoid-hemispheric. BERRY: large, subglobose to ellipsoid, orange,
pericarp thick. SEED: obovoid or subglobose to ellipsoid,
smooth, testa absent at maturity, embryo large, outer cell layers with chlorophyll, endosperm absent. See Plates 69, 122A.
CHROMOSOMES: 2n = 36, 40, 60, karyology very similar to
that of Anchomanes.
DISTRIBUTION: 10 spp.; tropical west and central Africa:–
?Benin, Cameroon, Congo, Equatorial Guinea (Bioko, Rio
Muni), Gabon, Ghana, Ivory Coast, Liberia, Malaysia
(Sarawak), Nigeria, Sierra Leone, ?Togo.
ECOLOGY: tropical humid forest; geophytes on forest floor.
ETYMOLOGY: after mythic Nephthys, mother of Anubis and
wife of Typhon.
69. Nephthytis
218
THE GENERA OF ARACEAE
TAXONOMIC ACCOUNTS: Bogner (1980c), Knecht (1983),
Ntépé-Nyame (1988), Namur & Bogner (1994), Hay, Bogner
& Boyce (1994).
70. Anchomanes
Anchomanes Schott in Oesterr. bot. Wochenbl. 3: 314
(1853). TYPE: A. hookeri Schott, nom. illeg. (= Caladium
petiolatum W.J. Hooker, A. petiolatus (W.J. Hooker)
Hutchinson).
HABIT: herbs, often very robust, tuber small to gigantic,
erect or grossly rhizomatous, seasonally dormant. LEAF: solitary, often gigantic. PETIOLE: very long, terete, aculeate,
rarely smooth, sheath very short. BLADE: sagittate when
juvenile, becoming dracontioid at maturity: i.e. trisect, primary divisions each further divided ± dichotomously or
pinnately, secondary divisions irregularly pinnatifid, ultimate lobes very variable in size and shape, distal ones larger,
trapezoid, apically broader, truncate or shallowly bifid,
decurrent to sessile, proximal lobes ovate and acuminate;
primary lateral veins of ultimate lobes pinnate, long-arcuate,
mostly running into margin, sometimes forming irregular
submarginal collective vein, higher order venation reticulate.
INFLORESCENCE: solitary, usually appearing before leaf.
PEDUNCLE: aculeate, rarely smooth, shorter than petiole.
SPATHE: erect, broadly ovate to narrowly oblong-lanceolate
or oblong-elliptic, boat-shaped, not constricted, convolute
basally or not at all, apex sometimes fornicate, marcescent.
SPADIX: much shorter or subequal to spathe, sessile to subsessile, cylindric, female zone subequal to male zone or
much shorter, male zone contiguous with female, fertile to
apex. FLOWERS: unisexual, perigone absent. MALE
FLOWER: stamens free, anthers sessile or filaments short,
compressed, connective slender below, thickened and
dilated apically, thecae ovate-oblong, opposite, dehiscing by
apical slit. POLLEN: extruded in strands, inaperturate, ellipsoid to ellipsoid-oblong, large (mean 64 µm., range 37–94
C
26d Tribes & Genera Acro 18/7/97 6:36 Page 219
A
L
B
D
M
E
C
G
F
J
K
W
Q
V
R
S
H
N
P
T
U
Plate 69. Nephthytis. A, habit × 1/2; B, stamen × 10; C, stamen, longitudinal section × 10; D, gynoecium × 10; E, gynoecium, longitudinal
section × 10; F, habit × 1/2; G, leaf × 1/2; H, spadix × 1; J, stamen × 10; K, stamen, longitudinal section × 10; L, gynoecium × 10; M, gynoecium, longitudinal section × 10; N, habit × 1/2; P, habit × 1/5; Q, inflorescence × 1; R, stamen × 10; S, stamen, longitudinal section × 10; T,
gynoecium × 10; U, gynoecium, longitudinal section × 10; V, infructescence × 1; W, seed, hilum view × 1. Nephthytis hallaei: A, Bogner 750
(K & Kew spirit collection 46624); B–E, Bogner 750 (Kew spirit collection 54219); N. swainei: F, Swaine et al. GC 44621 (K); N. poissonii: G,
Bogner 605 (K); H–M, Cult. Kew 1957–43801 (Kew spirit collection 51366); N. constricta: N, Brenan 8527 (K); N. afzelii: P, V–W, Knecht 6
(Cult. Kew 1982–4608); Q, Knecht 6 (Kew spirit collection 46572); R–U, Knecht 6 (Kew spirit collection 46103).
NEPHTHYTIDEAE : NEPHTHYTIS
219
26d Tribes & Genera Acro 18/7/97 6:36 Page 220
E
F
DD
D
R
P
EE
C
K
FF
AA
H
Q
J
CC
BB
M
S
T
W
X
L
N
G
A
B
Z
Y
V
U
Plate 70. Anchomanes. A, habit in flower × 1/10; B, habit in fruit × 1/10; C, habit × 1/20; D, part of mature leaf × 2/3; E, seedling leaf ×
1/3; F, juvenile leaf × 1/3; G, inflorescence × 2/3; H, stamen, top view × 6; J, stamen, longitudinal section × 6; K, gynoecium, longitudinal
section × 6; L, infructescence × 1/2; M, seed × 2; N, inflorescence × 2/3; P, stamen, top view × 6; Q, stamen, longitudinal section × 6; R, gynoecium × 6; S, inflorescence × 2/3; T, stamen, top view × 6; U, stamen, longitudinal section × 6; V, gynoecium × 6; W, inflorescence × 2/3; X,
stamen, top view × 6; Y, stamen, longitudinal section × 6; Z, gynoecium × 6; AA, stamen, top view × 6; BB, stamen, longitudinal section ×
6; CC, gynoecium × 6; DD, stamen, top view × 6; EE, stamen, longitudinal section × 6; FF, gynoecium × 6. Anchomanes welwitschii: A, Bullock
1215 (Kew photograph collection); B, Cult. Kew 14/12/59 (Kew slide collection); A. difformis: C, Croat s.n. (Kew photograph collection);
D, Lowe 2116 (K); A. welwitschii: E–F, Fanshawe 8549 (K); A. difformis: G–K, Cult. Kew 1961–38601 (Kew spirit collection 29047.636); L–M,
Milne-Redhead 2676 (Kew spirit collection 18904); A. nigritianus: N–R, Cult. Kew 1976.00789 Bogner 640 (Kew slide collection & Kew spirit
collection 29047.1); Bogner 662 (Kew spirit collection 37350); A. abbreviatus: S–V, Cult. Kew 1951–556 Greenway s.n. (Kew spirit collection
21975); Cult. Kew 1952.51801 Faulkner 878 (Kew slide collection); A. boehmii: W–Z, Bally 7558 (K & Kew spirit collection 56560); Shabani
11 (K); A. petiolatus: AA–CC, Boughey 163 (Kew spirit collection 16869); A. welwitschii: DD–FF, Cult. Kew (Kew spirit collection 22258).
220
THE GENERA OF ARACEAE
26d Tribes & Genera Acro 18/7/97 6:36 Page 221
70. Anchomanes
µm.), exine psilate or obscurely verruculate, very thin.
FEMALE FLOWER: ovary 1-locular, ovule 1, erect, anatropous,
funicle very short, placenta basal, stylar region shortly conic
or absent, sometimes strongly deflexed towards spadix base,
stigma either 2-lobed and reniform to V-shaped or discoid
or depressed-globose. BERRY: large, oblong-ellipsoid,
fleshy, borne in cylindric spike, red, purplish or partly
white. SEED: obovoid to oblong-ovoid, testa very thin,
smooth, transparent, embryo large, green, endosperm
absent. See Plates 70, 122B.
CHROMOSOMES: 2n = 40, very large.
DISTRIBUTION: 7–8 spp.; tropical Africa: Angola, Benin,
Burkina Faso, ?Cabinda, Cameroon, Central African Republic,
Chad, Congo, Equatorial Guinea (Bioko, Rio Muni), Gabon,
Gambia, Ghana, ?Guinea, ?Guinea-Bissau, Ivory Coast, Kenya,
Liberia, ?Malawi, Mozambique, Nigeria, Senegal, Sierra Leone,
Sudan, Tanzania, Togo, Uganda, Zaïre, Zambia.
ECOLOGY: tropical humid forests, savannas (A. welwitschii),
near swamp (A. boehmii); geophytes, in leaf litter between
rocks or on forest floor, seasonally dormant.
NOTES. The only clear cut distinction between Anchomanes
and Pseudohydrosme is locule number.
ETYMOLOGY: Greek agchein (to strangle) and mainesthai
(to rage); old plant name by Appuleius.
TAXONOMIC ACCOUNTS: Engler (1911), Knecht (1983),
Mayo & Bogner in Mayo (1985a), Ntépé-Nyame (1988).
C
71. Pseudohydrosme
Pseudohydrosme Engler in Bot. Jahrb. 15: 455 (1892,
“1893”). LECTOTYPE: P. gabunensis Engler (see N.E. Brown
in Thiselton-Dyer, Fl. Trop. Africa 8: 160. 1901, “1902”).
SYNONYM: Zyganthera N.E. Brown in Thiselton-Dyer, Fl.
Trop. Africa 8: 160 (1901, “1902”).
HABIT: large, seasonally dormant herbs, tuber subglobose,
subterranean, with annular leaf scars, growing continuously
and not renewed with each growing period. LEAF: solitary,
large. PETIOLE: long, aculeate, sheath very short. BLADE:
dracontioid: i.e. trisect, primary divisions pinnatifid or bip-
71. Pseudohydrosme
innatifid to pinnatisect, ultimate (distal) lobes mostly truncate
to shallowly bifid, sessile to decurrent, proximal lobes acuteacuminate; primary lateral veins of ultimate lobes pinnate,
forming irregular submarginal collective vein or running into
margin, higher order venation reticulate. INFLORESCENCE:
solitary, appearing before leaf. PEDUNCLE: aculeate, very
short, much shorter than petiole. SPATHE: large, somewhat
resembling the horn of a euphonium, unconstricted, bright
yellow, dark purple within and at mouth of tube, tube convolute, fleshy, obconic, blade very broad, thinner, with
flaring, auriculate margins, fornicate. SPADIX: very short,
sessile, female zone subcylindric, male zone cylindric,
obtuse, subequal to or longer than female, fertile to apex (P.
gabunensis) or with appendix covered with sterile flowers
(P. buettneri). FLOWERS: unisexual, perigone absent. MALE
FLOWER: 2–5-androus, stamens free, subprismatic, compressed, anthers sessile, connective thick, broad,
overtopping thecae, thecae oblong, long, lateral, dehiscing
by apical pore. POLLEN: extruded in strands, inaperturate,
ellipsoid-oblong, very large (mean 106 µm., range 93–114
µm.), exine psilate to slightly scabrous. STERILE MALE
FLOWERS: composed of subprismatic, free staminodes.
FEMALE FLOWER: ovary globose to broadly ellipsoid, sometimes compressed, 2(–3)-locular, ovules 1 per locule,
anatropous, funicle short, placenta axile at base of septum,
stylar region attenuate to cylindric, narrower than ovary,
stigma thick, 2(–3)-lobed, concave centrally. BERRY:
unknown. SEED: unknown. See Plates 71, 122C.
CHROMOSOMES: 2n = ca. 40.
DISTRIBUTION: 2 spp.; tropical Africa:– Gabon.
ECOLOGY: tropical humid forest; geophytes on forest floor.
NOTES: Engler (1911) recognized 2 sections:– sect.
Pseudohydrosme (“Chorianthera”), sect. Zyganthera.
Pseudohydrosme buettneri (sect. Zyganthera) has never been
recollected and the type no longer exists. N.E. Brown considered this species to be sufficiently different to warrant
generic recognition.
ETYMOLOGY: Greek pseudo (false) and Hydrosme, itself
derived from hydra (water snake) and osmê (smell); in reference to its similarity to Hydrosme (now Amorphophophallus).
TAXONOMIC ACCOUNTS: Engler (1911), Bogner (1981b).
NEPHTHYTIDEAE : PSEUDOHYDROSME
221
26d Tribes & Genera Acro 18/7/97 6:37 Page 222
F
G
E
H
A
J
C
B
D
Plate 71. Pseudohydrosme. A, habit × 1/10; B, portion of leaf × 1/2; C, section of petiole × 2/3; D, habit in flower × 1/2; E, spadix ×
2/3; F, stamen × 6; G, stamen, longitudinal section × 6; H, gynoecium × 6; J, gynoecium, longitudinal section × 6. Pseudohydrosme
gabunensis: A, Aroideana 4(1): 32, fig.2 (1981); B–D, Bogner 664 (K); Aroideana 4(1): 33, fig.6, 34, fig.8 (1981); E–J, Bogner 664 (Kew
spirit collection 45184).
222
THE GENERA OF ARACEAE
26e Tribes & Genera Acro 18/7/97 6:56 Page 223
C
Tribe Aglaonemateae
Tribe Aglaonemateae Engler in Nova Acta Acad. Leopold.Carol. 39: 148 (1876, “Aglaonemeae”).
Laticifers simple, articulated; leaf blade (linear-) ovate to
elliptic-oblong, base sometimes subcordate, primary lateral veins pinnate, forming single marginal vein, higher
order venation parallel-pinnate; spathe boat-shaped,
unconstricted; spadix with contiguous female and male
zones; flowers unisexual, perigone absent; stamens free,
thecae dehiscing by apical pore, pollen grains large, ovary
1-locular, ovule 1, anatropous, style short, narrower than
ovary, stigma broad, discoid, concave; berry large; seed
large, ellipsoid, testa smooth, thin, endosperm absent.
C
72. Aglaonema
Aglaonema Schott in Wiener Z. Kunst 1829 (3): 892 (1829).
TYPE: A. oblongifolium Schott, nom. illeg. (Arum integrifolium Link, Aglaonema integrifolium (Link) Schott).
HABIT: evergreen herbs, sometimes robust, stem epigeal,
erect and unbranched or creeping and often branched,
internodes green, smooth, often rooting at the nodes.
LEAVES: several, forming an apical crown. PETIOLE: sheath
usually long. BLADE: ovate-elliptic, narrowly elliptic, rarely
broadly ovate or sublinear, base often unequal, attenuate
to rounded, rarely cordate, often with striking, silvery and
pale green patterns of leaf variegation; primary lateral veins
pinnate, often weakly differentiated, running into marginal
vein, higher order venation parallel-pinnate. INFLORESCENCE: 1–9 in each floral sympodium. PEDUNCLE: shorter
or longer than petiole, deflexing in fruit. SPATHE: ovate to
± globose, erect, boat-shaped to convolute, not differenti-
ated into tube and blade, often apiculate, green to whitish,
slightly to strongly decurrent, marcescent. SPADIX: cylindric
to clavate, shorter or longer than spathe, stipe long to
almost absent, female zone rather few-flowered, contiguous with and much shorter than male zone, male zone
fertile to apex; rarely with staminodes. FLOWERS: unisexual, perigone absent. MALE FLOWER: stamens free, not
forming clear floral groups, filaments usually distinct, connective thickened, thecae opposite, obovoid, short,
dehiscing by apical pore or reniform transverse slit.
POLLEN: inaperturate, ellipsoid, large (mean 52 µm.), range
37–67 µm.), exine essentially psilate. FEMALE FLOWER:
ovary subglobose, 1-locular, ovule 1, anatropous, shortly
ovoid, funicle very short, placenta basal, stylar region short,
thick, stigma broad, discoid, concave centrally. BERRY:
ellipsoid, outer layer fleshy green but turning yellow, rarely
white and finally red. SEED: ellipsoid, almost as large as
berry, testa thin, ± smooth, tegmen inconspicuous, embryo
large, endosperm absent. See Plates 72, 122D.
CHROMOSOMES: 2n = 40, 60, 80, 100, 120 (70, 110).
DISTRIBUTION: 21 spp.; tropical Asia, Malay Archipelago,
Papuasia:– Bangladesh, Brunei, Burma, Cambodia, China
(Guandong, Guangxi, Hainan, Yunnan), India (NE),
Indonesia (Borneo, Java, Moluccas, Sulawesi, Sumatra), Laos,
Malaysia (Borneo, Peninsula), Papua New Guinea,
Philippines, Thailand, Vietnam.
ECOLOGY: tropical humid forest; terrestrial on forest floor,
occasionally in deciduous forest or regrowth, also in humus
deposits on limestone and in peat deposits.
COMMON NAMES AND USES: chinese evergreen, very
widely cultivated as an ornamental plant.
ETYMOLOGY: Greek aglaos (splendid) and nema, nêmatos
(stamen).
TAXONOMIC ACCOUNTS: Engler (1915), Nicolson (1969),
Jervis (1980).
72. Aglaonema
AGLAONEMATEAE : AGLAONEMA
223
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E
C
D
F
B
J
H
G
A
K
L
Plate 72. Aglaonema. A, habit × 1/4; B, leaf × 1/3; C, detail of leaf venation × 4; D, spadix × 1; E, stamen × 10; F, inflorescence × 1; G, staminode × 10; H, gynoecium × 10; J, gynoecium, longitudinal section × 10; K, habit × 1/4; L, inflorescence × 1. Aglaonema simplex : A–C,
Cult. Kew 1963–43405; D–E, Giles & Woolliams PB109 (Kew spirit collection 37985); A. simplex : F–J, Hay 2001 (Kew spirit collection 59067);
A. modestum: K, Cult. Kew 1968–38227; A. hookerianum: L, Cult. Kew (Kew spirit collection 22425).
224
THE GENERA OF ARACEAE
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C
73. Aglaodorum
Tribe Culcasieae
C
Aglaodorum Schott, Gen. Aroid. t. 58 (1858). TYPE: A. griffithii (Schott) Schott (Aglaonema griffithii Schott).
Tribe Culcasieae Engler in Engler & Prantl, Nat. Pflanzenfam. II (3): 112, 116 (1887).
HABIT: evergreen herb, stem rhizomatous, creeping,
aerenchymatous stem, much-branched, . LEAVES: several to
many. PETIOLE: terete, sheath short. BLADE: oblanceolate
to oblong, thick; midrib very thick, primary lateral veins
pinnate, weakly differentiated, higher order venation parallel-pinnate. INFLORESCENCE: solitary. PEDUNCLE: long,
subequal to petiole, erect in fruit. SPATHE: oblong, cuspidate, convolute, erect. SPADIX: stipitate, a little shorter than
spathe, female zone very short with a single whorl of flowers, male zone subcylindric, fertile to apex. FLOWERS:
unisexual, perigone absent. MALE FLOWER: stamens free,
short, prismatic, filaments distinct, connective thickened,
thecae oblong, adjacent or opposite, dehiscing by apical
pore. POLLEN: inaperturate, ellipsoid, large (mean 59 µm.),
exine apparently psilate or verruculate. FEMALE FLOWER:
gynoecium surrounded by whorl of 1–3 shorter prismatic staminodes, ovary 1–2-locular, ovule 1 per locule, anatropous,
funicle very short, placenta parietal in 1-locular ovaries,
stigma broad, discoid, 4-lobed, concave at centre. BERRY:
obovoid to ellipsoid, large, pericarp very thick, green. SEED:
large, ellipsoid, testa thin, smooth, embryo large, plumule
well-developed, endosperm absent. See Plates 73, 123A.
CHROMOSOMES: 2n = 40.
DISTRIBUTION: 1 sp.; Indonesia (Sumatra), Malaysia
(Borneo, Peninsula), Vietnam.
ECOLOGY: tropical open swamps, especially freshwater tidal
zones and brackish water, often growing with Nypa fruticans
and Cryptocoryne ciliata; creeping rhizomatous helophyte.
ETYMOLOGY: Greek aglaos (splendid) and dôron (gift), a
poetic name.
TAXONOMIC ACCOUNTS: Engler (1915), Nicolson (1969).
Laticifers present, simple, articulated (Cercestis) or absent
(Culcasia), resin canals present in roots, stems and leaves,
sclerotic hypodermis present in roots; usually climbing
hemiepiphytes with slender stems (rarely robust), sometimes
erect or prostrate terrestrial plants; petiole geniculate apically; primary lateral veins pinnate, higher order venation
reticulate; female zone of spadix contiguous with male or
separated by zone of sterile male flowers; flowers unisexual,
perigone absent; male flower 2–4 androus, stamens free,
anthers subsessile, lacking endothecial thickenings, connective usually strongly thickened, broad, truncate, thecae
dehiscing by short apical slit or pore; ovules 1 per locule,
stigma sessile, large, discoid; berries ± globose, usually red;
seed testa thin, endosperm absent.
C
74. Culcasia
Culcasia Palisot de Beauvois, Fl. Oware 1: 3 (1805), nom.
cons. TYPE: C. scandens Palisot de Beauvois (typ. cons.).
SYNONYM: Denhamia Schott in Schott & Endlicher,
Melet. Bot. 19 (1832).
Laticifers absent. HABIT: erect, repent or climbing herbs, rooting at least from lower nodes, branches slender. LEAVES: many,
often forming terminal crown in terrestrial species. PETIOLE:
geniculate apically, geniculum often inconspicuous, sheath
persistent, rather long. BLADE: lanceolate or oblanceolate to
ovate or ovate-oblong, rarely rounded, rarely pubescent below,
resin canals pellucid, linear or punctate; primary lateral veins
pinnate, often forming submarginal collective vein, otherwise
running into marginal vein, higher order venation reticulate.
73. Aglaodorum
CULCASIEAE : CULCASIA
225
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F
E
B
D
A
G
C
Plate 73. Aglaodorum. A, habit × 2/3; B, inflorescence × 1; C, spadix × 2; D, stamen × 8; E, gynoecium with associated staminode × 8; F,
gynoecium, longitudianal section × 8; G, fruit × 1. Aglaodorum griffithii: A, C–G, Bogner 1767 (M); Bogner 1672 (Kew spirit collection 49830);
B, Boyce (Kew slide collection).
226
THE GENERA OF ARACEAE
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A
B
K
T
C
M
L
F
H
G
P
N
J
R
S
Q
D
E
Plate 74. Culcasia. A, habit × 1/3; B, juvenile habit × 1/3; C, habit × 1/3; D, leaf × 1/3; E, habit × 1/3; F, inflorescence × 1; G, inflorescence
× 1; H, stamens × 10; J, gynoecium, longitudinal section × 10; K, spadix × 5; L, detail of stamens, top view × 4; M, detail of gynoecia × 4; N,
stamens × 10; P, gynoecium, longitudinal section × 10; Q, habit × 2/3; R, stamens × 10; S, gynoecium, longitudinal section × 10; T, seed × 1
1/2. Culcasia parviflora: A, Keay IFH 37529 (K); B, Bogner 697 (K); C. angolensis: C, Johnson s.n. (K); Robyns 1140 (K); C. panduriformis:
D, Zenker 4572 (K); C. longevaginata: E, Baldwin 9226 (K); C. striolata: F, Milne-Redhead 5155 (Kew spirit collection 22442); C. orientalis:
G–J, Bogner 140 (Kew spirit collection 22712); C. seretii: K–M, Cult. Kew 1982–04604 (Kew spirit collection 46485); C. saxatilis: N–P, Meikle
1275 (Kew spirit collection 25627); C. rotundifolia: Q–S, Bogner 749 (K & Kew spirit collection 56676); C. liberica: T, Cult. Kew 1982–04601
(Kew spirit collection 51491).
CULCASIEAE : CULCASIA
227
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INFLORESCENCE: 1–12(–20) in each floral sympodium, internodes of floral sympodium sometimes relatively elongated.
PEDUNCLE: short to relatively long. SPATHE: erect, green to
whitish, boat-shaped, not or hardly constricted, convolute
basally, gaping apically at anthesis, deciduous to marcescent.
SPADIX: subsessile to stipitate, cylindric-clavate, equal to or
somewhat longer than spathe, female zone usually densely
flowered, rarely laxly, shorter than male zone and either contiguous with it or separated by a laxly flowered zone of sterile
male flowers, male zone fertile to apex, axis often persistent in
fruit. FLOWERS: unisexual, perigone absent. MALE FLOWER:
2–4-androus, stamens free, short, obpyramidal, truncate apically, anthers subsessile, connective thick, thecae oblong,
dehiscing by short apical slit. POLLEN: inaperturate, subspheroidal, medium-sized (mean 32 µm., range 27–40 µm.),
exine verrucate to rugulate or subreticulate, usually with psilate
patches of variable size, rarely spinose. STERILE MALE FLOWERS: with 3–4 obpyramidal, depressed staminodia. FEMALE
FLOWER: ovary depressed, 1–3-locular, ovules 1 per locule,
anatropous, funicle short, placentae subbasal, stigma sessile,
hemispheric-discoid, relatively large, sometimes weakly lobed.
BERRY: globose to ellipsoid, 1–3-seeded, mostly red, sometimes
orange to greenish-yellow, infructescence subglobose to cylindric. SEED: ovoid to ellipsoid, testa thin, smooth, brown,
plumule lateral, superficial, with leaf primordia (C.liberica),
endosperm absent. See Plates 74, 123B.
CHROMOSOMES: 2n = 42, 84.
DISTRIBUTION: ca. 27 spp.; tropical Africa:– Angola, Benin,
Burkina Faso, ?Burundi, Cabinda, Cameroon, Central African
Republic, Congo, Equatorial Guinea (Bioko, Rio Muni),
Gabon, ?Gambia, Ghana, Guinea, ?Guinea-Bissau, Ivory
Coast, Kenya, Liberia, Mali, Niger, Nigeria, ?Rwanda, Senegal,
Sierra Leone, Tanzania, Togo, Uganda, Zaïre.
ECOLOGY: tropical moist and humid forest; usually climbing
hemiepiphytes, sometimes terrestrial, terrestrial species tend
to occur in damp forest sites.
ETYMOLOGY: variant of Middle Eastern name qolqas, (also
the origin of the name Colocasia).
TAXONOMIC ACCOUNTS: Engler (1905), Bogner (1980b),
Knecht (1983), Mayo (1985a), Ntépé-Nyame (1988), Boyce
(1995b).
74. Culcasia
228
THE GENERA OF ARACEAE
75. Cercestis
Cercestis Schott in Oesterr. bot. Wochenbl. 7: 414 (1857).
TYPE: C. afzelii Schott
SYNONYMS: Alocasiophyllum Engler in Bot. Jahrb. 15:
449 (1892, “1893”); Rhektophyllum N.E. Brown in J. Bot. 20:
194 (1882).
Laticifers present, simple, articulated. HABIT: climbing herbs,
sometimes creeping, small to robust, stem long, producing flagelliform shoots with long internodes and bearing only
cataphylls, followed by thicker, flowering stems with several
foliage leaves and short internodes. LEAVES: many. PETIOLE:
geniculate apically, geniculum sometimes inconspicuous,
sheath short to long. BLADE: oblong-lanceolate or oblong to
cordate, sagittate, or hastate, or trifid with acuminate segments, sometimes laciniate-pinnatifid with slit-like perforations
extending to margin forming large rhomboid to obtriangular
lobes (C. camerunensis, C. mirabilis), resin canals pellucid,
linear or punctate; primary lateral veins pinnate, running into
marginal vein, higher order venation reticulate. INFLORESCENCE: usually 1–4 in each floral sympodium (up to 16 in C.
camerunensis). PEDUNCLE: shorter than spathe. SPATHE:
erect, thick, boat-shaped to subcylindric, convolute basally
into a tube, gaping apically at anthesis, not or hardly constricted, persistent to marcescent. SPADIX: sessile, shorter
than spathe, female zone shorter and contiguous with male.
FLOWERS: unisexual, perigone absent. MALE FLOWER: 2–4androus, stamens free, prismatic, slightly narrowed basally,
usually short and relatively broad, sometimes rather long and
narrow (C. camerunensis, C. mirabilis), filaments very short,
connective broad, thecae shortly oblong to almost linear,
dehiscing by small apical slit. POLLEN: extruded in strands,
inaperturate, ellipsoid to oblong or spherical to subspheroidal, medium-sized (mean ca. 40 µm., range 36–55 µm.),
exine obscurely fossulate-verrucate, or almost perfectly psilate
(C. camerunensis, C. mirabilis). FEMALE FLOWER: ovary
obovoid, 1-locular, ovule 1, hemianatropous to anatropous,
rarely campylotropous (C. taiensis), funicle very short, placenta parietal to subbasal, stigma sessile to subsessile, often
rather broad, discoid, often somewhat concave centrally.
75. Cercestis
C
26e Tribes & Genera Acro 18/7/97 6:57 Page 229
J
L
N
M
K
B
Q
A
P
C
H
F
G
D
E
Plate 75. Cercestis. A, flowering shoot arising from leafless continuation shoot, attached to twig by aerial roots × 1/2; B, leaf × 1/2; C, leaf
× 1/2; D, inflorescences with associated stem and petiole base × 1/2; E, male flower × 6; F, gynoecium × 6; G, gynoecium, longitudinal section × 6; H, spadix, J, detail of male zone of spadix × 6; K, detail of female zone of spadix × 6; L, male flower × 9; M, gynoecium × 9; N,
gynoecium, longitudinal section × 9; P, habit × 1/2; Q, fruiting habit × 1/2. Cercestis stigmaticus: A, Coombe 169 (K); C. kamerunianus: B,
Jones 19526 (K); C. mirabilis: C, Bogner 601 (K); D, Bogner 705 (K); E–G, Bogner s.n. (K & Kew spirit collection 29047.471); C. dinklagei:
H–N, Hepper 7508 (Kew spirit collection 49930); C. afzelii: P, Jones & Onochie FHI 18753 (K); Q, Adams 3729 (K).
CULCASIEAE : CERCESTIS
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26e Tribes & Genera Acro 18/7/97 6:58 Page 230
BERRY: infructescence ellipsoid to oblong, berries obovoid to
subglobose or ellipsoid, red, pericarp thick. SEED: obovoid to
ellipsoid, testa smooth, thin, embryo large, outer cell layer
green, endosperm absent. See Plates 75, 123C.
CHROMOSOMES: 2n = 42, morphologically similar to those
of Culcasia.
DISTRIBUTION: 13 spp.; tropical Africa:– Angola, Benin,
?Burundi, ?Cabinda, Cameroon, Central African Republic,
Congo, Equatorial Guinea (Bioko, Rio Muni), Gabon, Gambia,
Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Nigeria,
?Rwanda, Senegal, Sierra Leone, ?Togo, Uganda, Zaïre.
ECOLOGY: tropical humid forest; climbing hemiepiphytes
and terrestrial plants.
ETYMOLOGY: Greek Cercestes, one of the fifty sons of
mythic Aegyptus.
TAXONOMIC ACCOUNTS: Engler (1911), Knecht (1983),
Mayo (1985a), Bogner (1986a), Ntépé-Nyame (1988), Bogner
& Knecht (1995).
C
Tribe Montrichardieae
Tribe Montrichardieae Engler in Nova Acta Acad. Leopold.Carol. 39: 144 (1876).
Laticifers simple, articulated, sclerotic hypodermis present in
roots; arborescent helophytes; leaf blade cordate-sagittate to trifid, primary lateral veins pinnate, higher order venation ±
reticulate; spathe deciduous after anthesis, slightly constricted,
differentiated into lower tube and upper, ± boat-shaped blade;
spadix: female and male zone contiguous, sterile flowers
absent; flowers unisexual, perigone absent; male flower 3–6androus, stamens free, ± sessile, connective overtopping thecae,
thecae dehiscing by short, apical slit, pollen large; ovary 1-locular, ovules 1–2, anatropous, placenta subbasal, style prismatic,
truncate, longer than ovary, ± excavated apically; berry and
seed large, plumule well-developed, endosperm absent.
C
76. Montrichardia
Montrichardia H. Crüger in Bot. Zeitung (Berlin) 12: 25
(1854), nom. cons. TYPE: M. aculeata (G.F.W. Meyer) Schott
(Caladium aculeatum G.F.W. Meyer).
SYNONYM: Pleurospa Rafinesque, Fl. Tell. 4: 8 (1838,
“1836”).
HABIT: robust to sometimes gigantic arborescent evergreen
herbs, stem erect, multiplying at base from hypogeal rhizomes, internodes well-developed, smooth or aculeate, ±
slender to massive. LEAVES: several, borne in terminal crown.
PETIOLE: sheath half as long as petiole or longer, with free
apical ligule. BLADE: cordate-sagittate to sagittate, hastate to
trifid, rarely trisect, posterior divisions often longer than anterior division; basal ribs well-developed, primary lateral veins
pinnate, running into marginal vein, secondary laterals ± parallel-pinnate, higher order venation reticulate.
INFLORESCENCE: 1(–2) in each floral sympodium. PEDUNCLE: shorter than petiole. SPATHE: erect, thick, entirely
deciduous after anthesis, ± constricted between tube and
blade, tube convolute, blade longer than tube, widely gaping at anthesis, ± boat-shaped. SPADIX: sessile, erect,
subequal to spathe, female zone cylindric, male zone subconoid, contiguous with and much longer than female zone,
fertile to apex. FLOWERS: unisexual, perigone absent. MALE
230
THE GENERA OF ARACEAE
76. Montrichardia
FLOWER: 3–6-androus, stamens free, obpyramidal-prismatic,
truncate at apex, anthers sessile, connective thick, overtopping thecae, thecae oblong-ellipsoid, dehiscing by longitudinal
slit. POLLEN: inaperturate, spherical to subspheroidal, large
(mean 94 µm., range 92–96 µm.), exine psilate. FEMALE
FLOWER: gynoecia prismatic-cylindric, ovary 1-locular, ovules
1–2, anatropous, funicle short, placenta subbasal to basal,
stylar region prismatic, thick, excavated and rugulose at apex,
stigma small, on low central boss, irregular to elliptic or
roundish. BERRIES: free, large, subcylindric, somewhat compressed, pericarp spongiose, at apex excavated and radiately
furrowed, 1-seeded. SEED: large, obovoid to ellipsoid, testa
smooth or rough, brown, embryo large, endosperm absent.
See Plate 76, 123D.
CHROMOSOMES: 2n = 48.
DISTRIBUTION: 2 spp.; tropical America, West Indies:–
Belize, Brazil (Amazonia, Northeast, South East), Colombia,
Costa Rica, French Guiana, Guatemala, Guyana, Honduras,
Lesser Antilles, Nicaragua, Panama, Peru, Puerto Rico,
Surinam, Trinidad, Tobago, Venezuela.
ECOLOGY: tropical humid forest; helophytes in tranquil
freshwater habitats, forming dense, often extensive stands
along river margins.
ETYMOLOGY: named after G. de Montrichard.
TAXONOMIC ACCOUNTS: Engler (1911), Jonker-Verhoef &
Jonker (1953), Lins (1994).
Tribe Zantedeschieae
Tribe Zantedeschieae Engler in Engler & Prantl, Nat.
Pflanzenfam. II (3): 113, 136 (1887).
Laticifers simple, articulated; stem a depressed-globose tuber
or short rhizome (Z. aethiopica); leaf blade lanceolate to
hastate-sagittate, primary lateral veins pinnate, forming single
marginal vein, higher order venation parallel-pinnate; peduncle long, sometimes longer than leaves; spathe ± obconic,
C
26e Tribes & Genera Acro 18/7/97 6:58 Page 231
F
R
Q
D
P
E
N
G
A
H
C
B
J
K
M
L
Plate 76. Montrichardia. A, habit × 1/10; B, flowering shoot × 1/2; C, base of stem showing rhizome × 1/2; D, mid–portion of stem × 1/2;
E, portion of stem showing prickles × 1/2; F, spadix × 1/2; G, stamens, top view × 3; H, stamen, side view × 5; J, gynoecium, top view showing irregular surface with stigma × 5; K, gynoecium, side view × 5; L, gynoecium, top view showing irregular surface with stigma × 3; M,
gynoecium, longitudinal section × 5; N, infructescence × 1/2; P, seed × 2; Q, leaf × 1/2; R, leaf × 1/2. Montrichardia linifera: A, Mayo s.n.
(Kew slide collection); M. arborescens: B, Philcox 8032 (K); Philcox et al. 8413 (Kew spirit collection 45821); C–E, Bogner 2188 (Kew spirit
collection 29047.760 & Kew illustration collection); Nelson 1729 (K); F, Simmons s.n. (K & Kew spirit collection 58906); G-M, Bogner 2188
(Kew spirit collection 29047.760); M. linifera: N–P, Stannard & Arrais (Kew spirit collection 51643 & 51644); Q, Harley et al. 24747 (K); M.
arborescens R, Nelson 1733 (K).
MONTRICHARDIEAE : MONTRICHARDIA
231
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unconstricted, tube subcylindric-obconic, blade gaping
widely; spadix shorter than spathe, male and female zones
contiguous; flowers unisexual, perigone absent; stamens free,
connective thickened apically, thecae dehiscing by apical
pore, pollen extruded in strands; ovary 1–5 locular, ovules
(1–)4(–8) per locule, anatropous, placenta axile to subapical;
berry green, orange or yellow; seed testa striate, endosperm
copious.
C
77. Zantedeschia
Zantedeschia K. Sprengel, Syst. Veg. 3: 756, 765 (1826),
nom. cons. TYPE: Z. aethiopica (L.) K. Sprengel (Calla
aethiopica L.), typ. cons.
SYNONYMS: ? Aroides Heister ex Fabricius, Enum., ed. 2,
42 (1763); Houttinia Necker, Elementa Botanica 3: 291 (1790);
Colocasia Link, Diss. Bot. 77 (1795), nom. rej.; Richardia
Kunth in Mém. Mus. Hist. Nat. 4: 433, 437 (1818, non L.
1753); Otosma Rafinesque, Fl. Tell. 4: 8 (1838, “1836”);
[Arodes O.Kuntze, Rev. Gen. 2: 739 (1891), orth. var.];
Pseudohomalomena A.D. Hawkes in Madroño 11: 147 (1951).
HABIT: seasonally dormant, sometimes evergreen (Z. aethiopica) herbs, tuber depressed-globose, or with thick
rhizome (Z. aethiopica). LEAVES: several, radical. PETIOLE:
spongiose, sheath long. BLADE: lanceolate, narrowly elliptic, cordate, cordate-sagittate, sagittate, hastate, often
variegated by aggregations of pale diaphanous necrotic
patches; primary lateral veins pinnate, running into distinct
marginal vein, secondary and tertiary laterals parallel-pinnate, higher order venation transverse-reticulate.
INFLORESCENCE: solitary in each floral sympodium,
appearing with leaves. PEDUNCLE: long, subequal or longer
than petiole. SPATHE: unconstricted, persistent, pure white,
cream, yellow, pink or rosy purple, lower part convolute
forming a short, stout, subcylindric to obconic tube, often
dark purple within at base, upper part widely gaping,
shorter than or subequal to tube, suberect or recurved with
somewhat revolute margins. SPADIX: erect, digitiform,
shorter than spathe, sessile or stipitate, male and female
zones contiguous, fertile to apex. FLOWERS: unisexual,
perigone absent. MALE FLOWER: 2–3-androus, stamens
free, anthers oblong, somewhat compressed, subsessile,
connective truncate at apex, separating thecae, thecae
opposite, oblong, dehiscing by apical pore. POLLEN:
extruded in strands, inaperturate, ellipsoid to oblong,
medium-sized (mean 40 µm., range 31–49 µm.), exine perfectly psilate to obscurely dimpled. FEMALE FLOWER: either
a naked gynoecium or rarely (Z. aethiopica, Z. odorata) surrounded by whorl of ca. 3 spathulate to clavate and apically
truncate staminodes, ovary ovoid, 1–5-locular, ovules
(1–)4(–8) per locule, anatropous, placenta axile to subapical,
stylar region short- to long-attenuate, stigma rather small,
discoid-subcapitate. BERRY: obovoid or depressed-globose,
1–several-seeded, usually green, or orange, rarely yellow,
and mucilaginous within (Z. aethiopica). SEED: ovoid to
ellipsoid, strophiolate, testa costate, embryo axile, elongate, endosperm copious. See Plates 77, 124A.
CHROMOSOMES: 2n = 32.
DISTRIBUTION: 8 spp.; southern Africa:– Angola, Botswana,
Lesotho, Malawi, ?Mozambique, Namibia, South Africa,
Swaziland, Tanzania, ?Zaire, Zambia, Zimbabwe.
ECOLOGY: tropical and subtropical damp open habitats;
helophytes, seasonally wet places, along streams, swampy
ground along forest edges, dry rocky hills.
NOTES: Zantedeschia aethiopica is morphologically distinct
from the other species; it is naturalized in various parts of
tropical America, in southern Europe, the Philippines, New
Zealand and elsewhere.
ETYMOLOGY: named after G. Zantedeschi (1773–1846).
TAXONOMIC ACCOUNTS: Engler (1915), Letty (1973), Perry
(1989), Singh, Wyk & Baijnath (1996).
Tribe Callopsideae
C
Tribe Callopsideae Engler in Engler & Prantl, Nat.
Pflanzenfam., Nachtr. 3: 29, 34 (1906).
Laticifers simple, articulated; small, evergreen herbs, rhizome
slender, hypogeal; leaf blade cordate-ovate, primary lateral
veins forming single marginal vein, higher order venation
reticulate; spathe completely expanded at anthesis, persistent;
spadix fertile to apex; female zone entirely adnate to spathe,
contiguous with male zone or with short naked zone in
between; flowers unisexual, perigone absent; stamens free,
anthers sessile, thecae opposite, dehiscing by apical pore;
gynoecia few, slender, ovary 1-locular, ovule 1, anatropous,
placenta basal, style long-attenuate, stigma small; embryo
elongate, endosperm copious.
78. Callopsis
Callopsis Engler in Notizbl. Königl. Bot. Gart. Berlin 1: 27
(1895). TYPE: C. volkensii Engler
77. Zantedeschia
232
THE GENERA OF ARACEAE
Laticifers simple, articulated. HABIT: small evergreen herb,
stem a slender hypogeal rhizome, internodes very short.
LEAVES: usually minutely hispid on petiole and abaxial surface of blade. PETIOLE: sheath very short. BLADE:
cordate-ovate; primary lateral veins pinnate, running into
marginal vein, higher order venation reticulate. INFLORESCENCE: 2 in each floral sympodium, appearing with the
C
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J
C
B
F
E
K
L
G
H
A
D
Plate 77. Zantedeschia. A, habit × 1/3; B, leaf × 2/3; C, inflorescence × 2/3; D, spadix × 2; E, stamens, top view × 9; F, stamen × 9; G, gynoecium × 9, H, gynoecium, longitudinal section × 9; J, infructescence × 2/3; K, leaf × 2/3; L, gynoecium with associated staminodes × 9.
Zantedeschia albomaculata subsp. albomaculata: A, Scheepers 36 (K); B, Codd 10688 (K); C–H, Milne-Redhead 3812 (Kew spirit collection
199162); J, Prosser 1827 (K); Z. rehmannii: K, Cult. Kew 1958–11001 (K); Z. aethiopica: L, Cult. Kew (Kew spirit collection 7467).
ZANTEDESCHIEAE : ZANTEDESCHIA
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E
F
D
A
C
B
Plate 78. Callopsis. A, habit with spathe of infructescence flattened out by pressing × 1; B, inflorescence, nearside and upper part of spathe
removed × 5; C, gynoecium, longitudinal section × 20; D, stamen × 20; E, berry, side view with hilum at top × 4; F, seed, side view × 4.
Callopsis volkensii: A, Faulkner 1709 (K); Greenway 4631 (K); Robertson & Luke 6468 (K); B–D, Bogner 218 (Kew spirit collection 56422);
E–F, Robertson & Luke 6468 (K).
234
THE GENERA OF ARACEAE
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leaves. PEDUNCLE: slender, equalling or longer than petiole, sometimes exceeding entire leaf. SPATHE: broadly
ovate-elliptic to subcircular, acuminate, decurrent, white, ±
fully expanded and sometimes arching backwards at anthesis, persistent, closing at fruiting stage. SPADIX: shorter than
spathe, female zone entirely adnate to spathe, ± laxly flowered with gynoecia ± biseriately arranged, contiguous with
male zone or with short, naked axis in between, male zone
equalling female, cylindric, densely flowered, fertile to apex.
FLOWERS: unisexual, perigone absent. MALE FLOWER:
probably 1-androus (2–3-androus according to Engler
1920a), stamens free, depressed subquadrate, anthers sessile, thecae opposite with subovoid microsporangia
dehiscing by apical pore. POLLEN: inaperturate, spherical
to subspheroidal, medium-sized (mean 37 µm.), exine papillate-spinose. FEMALE FLOWER: gynoecium slender,
flask-shaped, falcate, yellowish, ovary 1-locular, ovule 1,
anatropous, placenta basal, stylar region rather long-attenuate, stigma small, discoid-subhemispheric, slightly wider
than style. BERRY: ovoid-ellipsoid and slightly angled, style
forming persistent mucro, green. SEED: ovoid-ellipsoid,
testa ± smooth, thin, embryo elongate, straight to slightly
curved, endosperm copious. See Plates 78, 124B.
CHROMOSOMES: 2n = 36.
DISTRIBUTION: 1 sp.; Kenya, Tanzania.
ECOLOGY: tropical humid forest; creeping, rhizomatous geophytes, in leaf litter.
NOTES: Callopsis resembles Ulearum in various respects but
lacks anastomosing laticifers and has a narrower connective.
In Callopsis the thecae open by a pore which later becomes
a very broad slit. The two microsporangia of each theca thus
have a single common opening. The stamens appear to be
free and uniformly separated to a depth which reaches to the
base of the microsporangia. This makes it impossible to say
from mature material how many stamens form a male flower.
Developmental studies will probably show that the male
flower is unistaminate.
ETYMOLOGY: Calla and the Greek opsis (appearance).
TAXONOMIC ACCOUNTS: Engler (1920a), Bogner (1980c),
Mayo (1985a).
78. Callopsis
Tribe Thomsonieae
C
Tribe Thomsonieae Blume, Rumphia 1: 138 (1837); Bogner
et al. in Aroideana 8 (1): 14–25 (1985).
Laticifers simple, articulated; seasonally dormant, stem tuberous, occasionally rhizomatous, hypogeal; leaf usually 1;
petiole long, terete, variously maculate; blade dracontioid,
first foliage leaf of seedling divided, never entire, the three
primary leaf divisions upright in bud, ultimate lobes usually
elliptic-lanceolate, acuminate, primary lateral veins of ultimate lobes pinnate, forming submarginal collective vein,
higher order venation reticulate; inflorescence 1, subtended
by cataphylls; spadix with sterile terminal appendix, female
zone usually contiguous with male; flowers unisexual,
perigone absent; pollen extruded in strands, exine various;
ovules 1 per locule, anatropous; seed testa smooth, embryo
large, endosperm absent.
C
79. Amorphophallus
Amorphophallus Blume ex Decaisne in Nouv. Ann. Mus.
Hist. Nat. 3: 366 (1834), nom. cons. TYPE: A. campanulatus
Decaisne (= A. paeoniifolius (Dennstedt) Nicolson).
SYNONYMS: Thomsonia Wallich, Pl. Asiat. Rar. 1: 83
(1830), Bogner in Pl. Syst. Evol. 125 (1): 15–20 (1976), nom.
rej.; Pythion Martius in Flora 14: 458 (1831), nom. rej.;
Candarum Reichenb. ex Schott & Endlicher, Melet. Bot. 17
(1832), nom. illeg.; Pythonium Schott in Schott & Endlicher,
Melet. Bot. 17 (1832), nom. illeg.; Kunda Rafinesque, Fl. Tell.
2: 82 (1837, “1836”), nom. illeg.; Brachyspatha Schott, Syn.
Aroid. 35 (1856); Conophallus Schott, Syn. Aroid. 34 (1856);
Plesmonium Schott, Syn. Aroid. 34 (1856), Bogner in
Adansonia 20 (3): 305–308 (1980); Corynophallus Schott in
Oesterr. bot. Wochenbl. 7: 389 (1857); Allopythion Schott,
Gen. Aroid. t. 24 (1858); Hansalia Schott in Oesterr. bot.
Zeitschr. 8: 82 (1858); Hydrosme Schott, Gen. Aroid. t. 33
(1858); Rhaphiophallus Schott, Gen. Aroid. t. 27 (1858);
Synantherias Schott, Gen. Aroid. t. 28 (1858); Proteinophallus
J.D. Hooker in Bot. Mag. 101: t. 6195 (1875).
HABIT: seasonally dormant (sometimes irregularly so) or
rarely semi-evergreen herbs, often large, sometimes gigantic, tuber usually depressed-globose, sometimes irregularly
± elongate-cylindric, napiform or carrot-shaped, rarely rhizomatous or stoloniferous. LEAVES: usually solitary (rarely
2–3) in adult plants, sometimes 2–3 in seedlings. PETIOLE:
long, usually smooth, rarely verrucose to asperate, sometimes very thick, usually conspicuously spotted and marked
in a variety of patterns, sheath very short. BLADE: dracontioide: i.e. trisect, primary divisions pinnatisect, bipinnatisect
or dichotomously further divided, tubercles rarely present
at junction of divisions, secondary and tertiary divisions ±
regularly pinnatifid to pinnatisect, ultimate lobes oblongelliptic to linear, acuminate, decurrent, rarely petiolulate;
primary lateral veins of ultimate lobes pinnate, forming distinct submarginal collective vein, higher order venation
reticulate. INFLORESCENCE: always solitary, preceded by
cataphylls, usually flowering without leaves, rarely with the
leaves. PEDUNCLE: very short to long, similar to petiole.
SPATHE: variously coloured, marcescent and finally deciduous, boat-shaped and not or hardly convolute, or clearly
differentiated into tube and blade, sometimes constricted
between them; tube convolute, rarely connate (A. pusillus,
THOMSONIEAE : AMORPHOPHALLUS
235
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A
D
C
G
F
H
J
E
B
Plate 79 (i). Amorphophallus. A, habit × 1/20; B, habit × 1/18; C, habit × 1/0; D, part of leaf × 1/6; E, detail of leaf × 2/3; F, part of leaf
× 1/6; G, part of leaf × 1/6; H, detail of petiole × 2/3; J, detail of petiole × 2/3. Amorphophallus decus-silvae: A, Java (Kew slide collection);
A. maculatus: B, Bogner 600 (Kew illustration collection); A. sp.: C, Richards 741–64 (Kew slide collection); A. galbra: D–E, Brown 5801
(K); A. sp.: F, Cult. Kew. (K); A. dracontioides: G, Johnson 662 (K); A. paeoniifolius : H, Cult. Kew. (Kew slide collection); A. krausei : J, Cult.
Kew (Kew slide collection).
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C
D
B
A
J
N
E
F
G
H
K
L
M
Plate 79 (ii). Amorphophallus. A, inflorescence × 1/3; B, inflorescence × 1/3; C, spadix × 2/3; D, inflorescence × 1/3; E, inflorescence ×
2/3; F, detail of fertile part of spadix × 3; G, inflorescence × 1/8; H, inflorescence × 1/6; J, detail of spadix appendix × 2/3; K, inflorescence
× 2/3; L, inflorescence × 2/3; M, detail of fertile part of spadix and base of appendix × 3; N, inflorescence × 1/6; Amorphophallus pendulus:
A, Cult. Kew 1968–200 (Kew spirit collection 7237); A. krausei: B, H.AM. 40 (Kew slide collection); A. dracontioides: C, I.F.H.19156 (Kew
spirit collection 21971); A. lewallei: D, H.AM. 20B (Kew slide collection); A. sumawongii: E–F, Bogner 372 (Kew spirit collection 26332.44);
A. paeoniifolius: G, Bogner s.n. (Kew spirit collection 34673); H.AM. 41A (Kew slide collection ); A. hirtus: H, H.AM. 132A (Kew slide collection); J, (Kew spirit collection 58005); A. pusillus: K, H.AM. 246 (Kew slide collection); A. pygmaeus: L–M, Bogner 1948 Cult. Hetterscheid
(Kew spirit collection 59079); A. gomboczianus: N, H.AM. 3 (Kew slide collection).
THOMSONIEAE : AMORPHOPHALLUS
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A
E
D
G
C
B
F
H
J
K
S
L
M
N
Q
P
R
U
T
V
W
X
Y
Z
AA
BB
Plate 79 (iii). Amorphophallus. A, stamen × 10; B, gynoecium × 10; C, gynoecium, longitudinal section × 10; D, stamen × 10; E, gynoecium × 10; F, gynoecium, longitudinal section × 10; G, stamen × 10; H, gynoecium × 10; J, gynoecium, longitudinal section × 10; K,
inflorescence, nearside half of spathe removed × 4; L, stamen × 10; M, gynoecium × 10; N, gynoecium, longitudinal section × 10; P, stamen
× 10; Q, gynoecium × 10; R, gynoecium, longitudinal section × 10; S, gynoecium, transverse section × 10; T, stamen × 10; U, gynoecium ×
10; V, gynoecium, longitudinal section × 10; W, stamen × 10; X, gynoecium × 10; Y, gynoecium, longitudinal section × 10; Z, stamen × 10;
AA, gynoecium × 10; BB, gynoecium, longitudinal section × 10. Amorphophallus albispathus: A–C, H.AM 16 (Kew slide collection); A. pygmaeus: D–F, Bogner 1948 Cult. Hetterscheid (Kew spirit collection 59079); A. pendulus: G–J, Cult. Kew 1968–200 (Kew spirit collection 7237);
A. pusillus: K, H.AM. 246 (Kew slide collection); A. gomboczianus: L–N, Ash 1434 (Kew spirit collection 15077.14); A. hirtus: P–S, (Kew
spirit collection 58005); A. sumawongii: T–V, Bogner 372 (Kew spirit collection 26332.44); A. paeoniifolius: W–Y, Bogner s.n. (Kew spirit
collection 34673); A. dracontioides: Z–BB, I.F.H.19156 (Kew spirit collection 21971).
238
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C
A
B
D
F
E
G
Plate 79 (iv). Amorphophallus. A, tuber × 1/6; B, tuber × 1/6; C, spathe base interior sculpturing × 4; D, spathe base interior sculpturing
× 4; E, spathe base interior sculpturing × 4; F, spathe base interior sculpturing × 4; G, spathe base interior sculpturing × 4. Amorphophallus
longituberosus: A, H.AM.120 (Kew illustration collection); A. corrugatus: B, H.AM. 229 (Kew illustration collection); A. johnsonii: C, H.AM.
41 (Kew slide collection); A. maculatus: D, Bogner 600 (Kew slide collection); A. parvulus: E, H.AM. 26A (Kew slide collection); A. henryi:
F, H.AM. 97 (Kew slide collection); A. bulbifer: G, Bogner s.n., no other data (Kew slide collection).
A. elliotii), campanulate to cylindric or ventricose, inner surface smooth or longitudinally ribbed or near base
verruculose, scabrate or densely covered with scale- or hairlike processes or smooth; blade erect to spreading, smooth,
ribbed or variously undulate or frilled at margins. SPADIX:
sessile or stipitate, shorter or much longer than spathe;
female zone shorter, equalling or longer than male zone;
male zone cylindric, ellipsoid, conoid or obconoid, usually
contiguous with female, sometimes separated by a sterile
zone which may be naked, or bear prismatic, subglobose or
hair-like sterile flowers; terminal appendix usually present,
rarely absent or reduced to a stub, erect, sometimes horizontal, rarely pendent, very variable in shape, usually ±
conoid or cylindric, rarely ± globose, sometimes ± stipitate
or basally narrowed, usually smooth or bearing staminodelike structures near base or entirely covered with staminodes,
sometimes corrugate or densely to sparsely hirsute, or
grossly and irregularly crumpled. FLOWERS: unisexual,
perigone absent. MALE FLOWER: 1–6-androus, stamens free
or sometimes connate in basal flowers or throughout male
zone, short, filaments absent or distinct, connective fairly
thick, sometimes projecting beyond thecae, thecae obovoid
or oblong, opposite, dehiscing apically by an apical (rarely
lateral) pore or transverse slit. POLLEN: extruded in strands,
inaperturate, mostly ellipsoid to ellipsoid-oblong, occasionally spherical or subsphaeroidal, medium-sized to large
(mean 53 µm., range 34–82 µm.), exine striate, striate-reticulate,
psilate,
scabrate,
areolate,
fossulate,
punctate-foveolate, verrucate, or spinose. FEMALE FLOWER:
gynoecia usually crowded, sometimes ± distant, ovary subglobose to ovoid or obovoid, 1–4-locular, ovules 1 per
locule, anatropous, funicle very short to distinct, erect, placenta axile to basal, stylar region absent, short or very long,
conoid to cylindric, stigma variably shaped, entire and subglobose or 2–4-lobed or stellate or rarely punctiform,
sometimes large and brightly coloured. BERRY: sometimes
very large, 1- to few-seeded, orange to red, rarely blue or
white, infructescence ± cylindric. SEED: ellipsoid, testa
smooth, thin, embryo large, somewhat green superficially,
endosperm absent. See Plates 79i–iv, 124C–D.
CHROMOSOMES: 2n = 26, 28, 39.
DISTRIBUTION: ca. 170 spp. (W. Hetterscheid, pers. comm.);
tropical Africa, Madagascar, tropical Asia, Malay Archipelago,
Melanesia, Australasia:– Angola, Australia, Bangladesh, Benin,
Bhutan, ?Botswana, Brunei, Burkina Faso, Burma, ?Burundi,
?Cabinda, Cambodia, Cameroon, Central African Republic,
Chad, S. China (incl. Taiwan), Congo, Equatorial Guinea
(Bioko, Rio Muni), Ethiopia, Gabon, Gambia, Ghana, Guinea,
Guinea-Bissau, India, Indonesia, Ivory Coast, Japan, Kenya,
Laos, Liberia, Madagascar, Malawi, Malaysia, Mali,
Mozambique, ?Namibia, Nepal, Niger, Nigeria, Papua New
Guinea, Philippines, ?Rwanda, Senegal, Sierra Leone, Somalia,
South Africa, Sri Lanka, Sudan, Tanzania, Thailand, Togo,
Uganda, Vietnam, Zaire, Zambia, Zimbabwe.
ECOLOGY: tropical humid forest, seasonal forest, open
woodlands; geophytes, sometimes in humus deposits on
rocks (limestone), also in waste places or areas of human
habitation (e.g. A. paeoniifolius).
NOTES: About 14 sections or informal sectional groups are
currently recognized, although many of these may be unnatural (W. Hetterscheid, pers. comm.).
USES: The tubers of A. paeoniifolius and A. konjac are widely
used sources of carbohydrate foods in tropical Asia and Japan
respectively.
ETYMOLOGY: Greek amorphos (deformed) and phallus
(penis), referring to the spadix appendix (especially of A.
paeoniifolius).
TAXONOMIC ACCOUNTS: Engler (1911), Gagnepain (1942),
Hepper (1968), Hu (1968), Bogner (1976a), Li (1979), Sivadasan
(1982, 1986, 1989), Knecht (1983), Bogner, Mayo & Sivadasan
(1985), Mayo (1985a), Bogner (1986a), Nicolson (1988a), NtépéNyame (1988), Hay (1990a, c), Bogner (1989b), Bogner &
Hetterscheid (1992), Hetterscheid (1994), Hetterscheid &
Serebryanyi (1994), Hetterscheid, Yadav & Patil (1994),
Sivadasan, Mohanan & Rajkumar (1994), Bogner (1995),
Hetterscheid & Peng (1995), Hetterscheid & Ittenbach (1996).
THOMSONIEAE : AMORPHOPHALLUS
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79. Amorphophallus
C
80. Pseudodracontium
Pseudodracontium N.E. Brown in J. Bot. 20: 193 (1882).
LECTOTYPE: P. anomalum N.E. Brown (= P. lacourii (Lind.
& André) N.E. Brown)(see Nicolson in Taxon 16: 518. 1967).
HABIT: seasonally dormant herbs, tuber depressed-globose,
napiform or irregularly elongate. LEAVES: often more than 1.
PETIOLE: long, usually mottled or otherwise variegated, sheath
very short and inconspicuous. BLADE: dracontioid: i.e. trisect
with 3 ± equal primary divisions, anterior division sometimes
smaller than posterior divisions, primary divisions mostly pinnatisect or partly bipinnatisect, ultimate lobes decurrent, sessile
or shortly petiolulate, narrowly elliptic, acuminate; primary
lateral veins of ultimate lobes pinnate, forming submarginal
collective vein, 1 marginal vein also present, higher order
venation reticulate. INFLORESCENCE: solitary, usually appearing with leaves. PEDUNCLE: long, longer, shorter or subequal
to petiole, similar in appearance to petiole. SPATHE: erect,
boat-shaped, convolute basally, slightly fornicate, not constricted, green to yellow. SPADIX: sessile, shorter to subequal
to spathe, female zone shorter than male, densely flowered,
male zone laxly flowered, contiguous with female zone, terminal appendix usually shorter than male zone, with naked
basal stipe, ± conic, covered with sterile male flowers. FLOWERS: unisexual, perigone absent. MALE FLOWER: 3–6-androus,
flowers distinct, ± distant, filaments relatively long, connate to
± free, thecae subglobose, dehiscing by short slit or pore.
POLLEN: inaperturate, ellipsoid to oblong, medium-sized
(mean 48 µm.), exine narrowly striate. STERILE MALE FLOWERS: composed of clavate, irregularly ± connate staminodes,
not forming distinct floral groups. FEMALE FLOWER: ovary
ovoid to subglobose, 1-locular, ovule 1, anatropous, funicle
short, placenta basal, stylar region shortly attenuate, stigma discoid-subcapitate. BERRY: ellipsoid, with stigma remnant
persisting, 1-seeded. SEED: ellipsoid, testa smooth, brown,
raphe conspicuous, embryo large, ellipsoid, somewhat truncate
at each end, endosperm absent. See Plates 80, 125A.
80. Pseudodracontium
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D
E
C
F
A
B
Plate 80. Pseudodracontium. A, habit × 1/4; B, leaflet × 1/2; C, spadix × 1; D, stamen × 8; E, gynoecium × 8; F, gynoecium, longitudinal
section × 8. Pseudodracontium latifolium: A–B, Dransfield 6219 Cult. Kew. 1984–4105; C–F, Dransfield 6219 (Kew spirit collection 58899).
THOMSONIEAE : PSEUDODRACONTIUM
241
26e Tribes & Genera Acro 18/7/97 7:01 Page 242
C
F
A
D
B
J
K
G
E
L
H
M
Plate 81. Arophyton. A, habit × 1/6; B, leaf × 2/3; C, detail of leaf venation × 4; D, seedling × 2/3; E, inflorescence × 2/3; F, infructescence ×
2/3; G, habit × 2/3; H, spadix × 3; J, synandrium, top view × 10; K, synandrode, side view × 10; L, gynoecium with associated synandrode × 10;
M, gynoecium, longitudinal section × 10. Arophyton buchetii: A, 7542 (Kew slide collection); B–D, Bogner 207 (K); E–F, Bogner 207 (Kew spirit
collection 32138 & 34394). A. tripartitum var. tripartitum: F, Bogner 205 (Kew spirit collection 34400); G, Bogner 205 (K!); H–M, Morat 3626 (K).
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CHROMOSOMES: 2n = 26.
DISTRIBUTION: 7 spp.; tropical southeast Asia:– Cambodia,
Laos, Thailand, Vietnam.
ECOLOGY: tropical humid and deciduous forest, bamboo
forest; geophytes, on forest floor.
NOTE: Closely related to Amorphophallus, and characterized by the staminodial, stipitate appendix, constantly
1-locular ovaries and male flowers with long, partially connate filaments.
ETYMOLOGY: Greek pseudos (false) and Dracontium ; refers
to the similarity to Dracontium.
TAXONOMIC ACCOUNTS: Engler (1911), Gagnepain (1942),
Serebryanyi (1995).
C
Tribe Arophyteae
Tribe Arophyteae Bogner in Bot. Jahrb. 92: 9 (1972).
SYNONYM: Tribe Synandrodieae Buchet in Bull. Soc.
Bot. France 86: 279 (1939)
Laticifers simple, articulated; seasonally dormant, stem tuberous (except most Arophyton spp.); primary lateral veins
pinnate forming 1 submarginal collective vein and 1–2 marginal veins, higher order venation parallel-pinnate to
reticulate; spadix fertile to apex (except some Arophyton
spp.); flowers unisexual, perigone absent; male flower a
synandrium of partially or completely connate stamens
(sometimes reduced to 1 stamen), pollen spinose; gynoecium surrounded by cup-like synandrodium, ovary 1-locular,
ovule 1, orthotropous, placenta basal; testa thin, smooth,
embryo large, endosperm absent.
C
81. Arophyton
Arophyton Jumelle in Ann. Musée Colon. Marseille, 36
année, sér. 4, 6 (2): 23 (1928). TYPE: Arophyton tripartitum
Jumelle
SYNONYMS: Synandrogyne S. Buchet in Bull. Soc. Bot.
France 86: 69 (1939); Humbertina S. Buchet in Bull. Soc. Bot.
France 88: 848–849 (1941).
HABIT: seasonally dormant herbs, rhizomatous or tuberous.
LEAVES: 1–few. PETIOLE: sheath short. BLADE: cordate, hastate, trifid to trisect or pedatifid; primary lateral veins pinnate,
forming submarginal collective vein, secondary laterals sometimes parallel-pinnate, otherwise higher order venation
reticulate. INFLORESCENCE: (1–)2–3 in each floral sympodium. PEDUNCLE: subequal or shorter than petiole.
SPATHE: not or slightly constricted between tube and blade,
tube persistent at maturity or entire spathe marcescent, blade
widely spreading, white or cream to greenish within. SPADIX:
fertile to apex, or with short appendix, entirely free or female
zone partly adnate to spathe, female zone contiguous with
male, or separated by synandrodes or a few bisexual flowers. FLOWERS: unisexual, perigone absent. MALE FLOWER:
2–7-androus, stamens connate, synandrium elongate-ellipsoid, often irregularly shaped, shallow, truncate, sometimes
with a central slit, common connective broad, thecae marginal, broad-ellipsoid to globular, dehiscing by slit or pore on
upper surface. POLLEN: inaperturate, spherical to subspheroidal, medium-sized (mean 32 µm., range 27–36 µm.), exine
spinose. FEMALE FLOWER: gynoecium surrounded by cuplike synandrode, ovary 1-locular, ovule 1, orthotropous,
81. Arophyton
funicle usually short, placenta basal, stylar region short to relatively long and cylindric-conoid, or ± absent, stigma discoid.
STERILE FLOWERS: consisting of a truncate synandrode with
central cavity. BISEXUAL FLOWERS: as for female flowers,
but surrounded by synandrium bearing a few scattered thecae. BERRY: ellipsoid to fusiform or clavate, red or green.
SEED: ellipsoid to globular, testa thin, smooth, embryo large,
globular or ellipsoid, plumule subapical, endosperm absent.
See Plates 81, 125B.
CHROMOSOMES: 2n = 38, 54, 76 (40).
DISTRIBUTION: 7 spp.; Madagascar.
ECOLOGY: tropical humid, seasonal forest or deciduous forest on limestone; geophytes or epiphytes, litter-filled crevices
and holes.
ETYMOLOGY: Greek aron (Arum) and phyton (plant).
TAXONOMIC ACCOUNTS: Bogner (1972, 1975).
C
82. Carlephyton
Carlephyton Jumelle in Ann. Musée Colon. Marseille, 27
année, ser.3, 7: 187 (1919). TYPE: C. madagascariense
Jumelle
HABIT: seasonally dormant herbs, tuber depressed-globose.
LEAVES: 1–2(–3). PETIOLE: sheath short. BLADE: cordate; primary lateral veins pinnate, forming submarginal collective vein,
1–2 marginal veins also present, secondary and tertiary laterals
mostly parallel-pinnate, higher order venation reticulate. INFLORESCENCE: 1–2(–3) in each floral sympodium, appearing
before or with leaf. PEDUNCLE: shorter than petiole. SPATHE:
not constricted, upper half marcescent, lower part persistent, ±
fully expanded at anthesis, later closing, cream to dull purple
within. SPADIX: fertile to apex, lower part of female zone
adnate to spathe, male and female zones contiguous or with a
few bisexual flowers between them, sometimes (C. glaucophyllum) basal zone of spadix composed almost entirely of
bisexual flowers. FLOWERS: unisexual, perigone absent. MALE
FLOWER: 1–6-androus, stamens connate, synandrium somewhat angled, truncate apically, common connective broad,
thecae either marginal, projecting laterally and inverted, thus
AROPHYTEAE : CARLEPHYTON
243
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F
E
H
K
D
G
J
C
L
B
A
N
P
M
Plate 82. Carlephyton. A, habit in flower with leaf emerging × 2/3; B, leaf × 2/3; C, inflorescence × 2; D, synandrium, side view × 15; E,
synandrium, top view × 15; F, gynoecium with associated synandrode × 15; G, gynoecium, longitudinal section × 15; H, bisexual flower ×
15; J, bisexual flower, longitudinal section × 15; K, infructescence × 1; L, habit × 2/3; M, inflorescence × 2; N, synandrium, top view × 10;
P, gynoecium with associated synandrode × 15. Carlephyton madagascariense: A, Bot. Jahrb. Syst. 92: 50, Fig. 4 (1972); B, Bogner 169 (K);
C–J, Bogner 169 (Kew spirit collection 56421); K, Bogner 279 (Kew spirit collection 34032); C. diegoense: L, 6449 (Kew slide collection);
M–P, Bogner 234 (Kew spirit collection 7700).
244
THE GENERA OF ARACEAE
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83. Colletogyne
82. Carlephyton
dehiscing by slit on lower surface, or stamens not completely
connate, upper part of filaments ± free and thickened with
thecae dehiscing by apical slit, sometimes remote. POLLEN:
inaperturate, spherical or subspheroidal, medium-sized (mean
34 µm., range 33–35 µm.), exine spinose. FEMALE FLOWER:
gynoecium surrounded by cup-like synandrode, ovary 1-locular, ovule 1, orthotropous, funicle short, placenta basal, stylar
region, short, stigma discoid to subhemispheric. BISEXUAL
FLOWERS: gynoecium surrounded by synandrium bearing 1–4
thecae, ovary as above. BERRY: ellipsoid to fusiform, orangered. SEED: ellipsoid, testa thin, smooth, embryo ellipsoid,
plumule lateral, endosperm absent. See Plates 82, 125C.
CHROMOSOMES: 54, 108.
DISTRIBUTION: 3 spp.; northern Madagascar.
ECOLOGY: tropical deciduous forest on limestone or basalt;
geophytes, in rock crevices and holes with leaf litter.
NOTES: Bogner (1972) recognized 2 sections:– sect.
Carlephyton, sect. Pseudocolletogyne.
ETYMOLOGY: named for G. Carle with the Greek suffix
-phyton (plant).
TAXONOMIC ACCOUNTS: Bogner (1972, 1975).
C
gated, anther apical-oblique, thecae ellipsoid, dehiscing by
slit. POLLEN: inaperturate, spherical, medium-sized (mean 39
µm.), exine spinose, obscurely verruculate between spines,
spines long, stout. FEMALE FLOWER: gynoecium surrounded
by a cup-like, variegated synandrode, ovary ovoid-ellipsoid,
1-locular, ovule 1, orthotropous, funicle short, placenta basal,
stylar region shortly attenuate, stigma discoid-capitate.
BERRY: fusiform, stigma remnant persistent, reddish-spotted. SEED: ellipsoid, testa thin, smooth, embryo with lateral
plumule, endosperm absent. See Plates 83, 125D.
CHROMOSOMES: 2n = 54.
DISTRIBUTION: 1 sp.; northern Madagascar.
ECOLOGY: tropical deciduous forest, on limestone; geophytes in holes or crevices with leaf litter.
NOTES: The 1-androus male flowers are thought to have
been derived phylogenetically from multistaminate synandria (Bogner 1972).
ETYMOLOGY: Greek kollêtos (glued together) and gynê
(woman); the female part of the spadix is adnate to the spathe.
TAXONOMIC ACCOUNTS: Bogner (1972, 1975).
Tribe Peltandreae
C
83. Colletogyne
Colletogyne Buchet in Bull. Soc. Bot. France 86: 23 (1939).
TYPE: C. perrieri Buchet
HABIT: seasonally dormant herb, tuberous. LEAVES: 1 (–2).
PETIOLE: sheath short. BLADE: cordate; primary lateral veins
pinnate and also arising from petiole insertion, forming
submarginal collective vein, 1–2 marginal veins also present,
secondary and tertiary laterals mostly parallel-pinnate, higher
order venation reticulate. INFLORESCENCE: 1–3 in each floral sympodium, appearing before or with leaves. PEDUNCLE:
shorter than petiole. SPATHE: obovate, not constricted, erect,
fully expanded at anthesis, closing later and persisting to
fruiting stage, red-spotted on greenish background. SPADIX:
fertile to apex, female zone adnate to spathe, female and
male zones contiguous. FLOWERS: unisexual, perigone
absent. MALE FLOWER: 1-androus, filament conoid, varie-
Tribe Peltandreae Engler in Nova Acta Acad. Leopold.Carol. 39: 146 (1876).
SYNONYM: Tribe Typhonodoreae Engler in Nova Acta
Acad. Leopold.-Carol. 39: 146 (1876).
Laticifers simple, articulated; rhizome hypogeal; primary lateral veins of leaf blade pinnate, forming submarginal
collective vein, 1–2 marginal veins also present, higher order
venation ± parallel-pinnate; inflorescences usually 2,
infructescence pendent; spathe ± constricted centrally, tube
ellipsoid to oblong, persistent, blade gaping at anthesis, later
marcescent; flowers unisexual, perigone absent; male flower
a truncate, prismatic synandrium of connate stamens, fused
connectives very thick, thecae lateral, dehiscing by apical
pore or short slit; ovary 1-locular, ovules orthotropous, style
narrower than ovary; berry and seeds large, embryo large,
plumule well-developed, endosperm vestigial to absent.
PELTANDREAE : PELTANDRA
245
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B
A
D
E
F
C
Plate 83. Colletogyne. A, habit × 2/3; B, leaf × 2/3; C, inflorescence × 2; D, synandrium × 16; E, gynoecium with associated synandrode ×
16; F, gynoecium, longitudinal section × 16. Colletogyne perrieri: A, 5489 (Kew slide collection); B–F, Bogner 165 (Kew spirit collection 42467
& photograph (M)).
246
THE GENERA OF ARACEAE
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C
84. Peltandra
Peltandra Rafinesque in J. Phys. Chim. Hist. Nat. Arts 89: 103
(1819), nom. cons. TYPE: P. undulata Rafinesque (= P. virginica (L.) Rafinesque).
SYNONYMS: Lecontia W. Cooper ex Torrey, Compend.
fl. n. middle stat. 358 bis (1826); Rensselaeria L.C. Beck, Bot.
N. Middle U.S. 382 (1833).
HABIT: seasonally dormant herbs, rhizome short, hypogeal,
sometimes branching. LEAVES: several. PETIOLE: sheath
rather long, up to at least half as long as petiole. BLADE:
lanceolate to broadly ovate, sagittate, hastate or rarely cordate;
basal ribs well-developed, primary lateral veins pinnate, sometimes only weakly differentiated, forming submarginal
collective vein, 2 or more distinct marginal veins also present,
secondary laterals parallel-pinnate, higher order venation parallel-pinnate near midrib, becoming reticulate towards margin.
INFLORESCENCE: 1–2 in each floral sympodium. PEDUNCLE: subequal to or shorter than petiole, erect at anthesis, bent
downwards in fruit. SPATHE: constricted between tube and
blade, tube convolute, externally green to yellow-green, ellipsoid, persistent, blade green to white, erect, widely expanded
(P. sagittifolia) or only gaping (P. virginica), later deciduous.
SPADIX: sessile, cylindric, female zone shorter than male,
partially adnate to spathe, either contiguous with male zone
or with a short zone of sterile flowers in between, male zone
with short terminal appendix of sterile flowers. FLOWERS:
unisexual, perigone absent. MALE FLOWER: synandrium 4–5androus, truncate, often slightly excavated centrally, anthers
lateral, thecae adjacent, oblong-ellipsoid, dehiscing by apical
pore. POLLEN: inaperturate, ellipsoid or spherical, mediumsized (mean 33 µm., range 28–37 µm.), exine spinose (P.
virginica) or almost psilate (P. sagittifolia). FEMALE FLOWER:
gynoecium closely surrounded by 3–5 free staminodes or
some staminodes free and others connate or all connate into
a truncate-urceolate synandrode, ovary ovoid, 1-locular,
ovules 1–few, hemiorthotropous, funicle short, placenta parietal to basal, stylar region shortly attenuate, narrower than
84. Peltandra
ovary, stigma discoid-hemispheric. BERRY: obconical to irregularly subglobose, green to blackish-purple (P. virginica) or
red (P. sagittifolia), 1–3-seeded, with mucilaginous contents.
SEED: large, ovoid to subglobose, laterally flattened, embryo
large, plumule well-developed with 6–7 leaf primordia,
endosperm vestigial or absent. See Plates 84, 126A.
CHROMOSOMES: 2n = 56, 112.
DISTRIBUTION: 2 spp.; eastern North America:– Canada
(Ontario, Quebec), USA (Alabama, Arkansas, Carolinas,
Connecticut, Delaware, Florida, Georgia, Illinois, Indiana,
Kansas, Kentucky, Louisiana, Maine, Maryland,
Massachusetts, Michigan, Mississippi, Missouri, New
Hampshire, New Jersey, New York, Ohio, Pennsylvania,
Rhode Is., Tennessee, Texas, Vermont, Virginia, West Virginia,
Wisconsin).
ECOLOGY: temperate wetland habitats; helophytes, marshes,
along watercourses, brackish water.
ETYMOLOGY: Greek peltê (small shield) and aner, andros
(man).
TAXONOMIC ACCOUNTS: Engler (1915), Barkley (1944),
Huttleston (1953), Blackwell & Blackwell (1975).
C
85. Typhonodorum
Typhonodorum Schott in Oesterr. bot. Wochenbl. 7: 70
(1857). TYPE: T. lindleyanum Schott
SYNONYM: Arodendron Werth in Mitt. Sem. Orient.
Sprachen 4 (Abt. 3): 112 (1901).
HABIT: evergreen, robust to gigantic herb (to 4m), rhizome
thick, subterranean, spreading, terminal shoot forming massive banana-like pseudostem formed by the lower part of the
petiole sheaths. LEAVES: several in terminal crown. PETIOLE:
very long, free apical part relatively short, sheath extending
for most of petiole length. BLADE: very large, subtriangular
to sagittate, acute; basal ribs well-developed, primary lateral
veins pinnate, forming submarginal collective vein very near
to margin, 3–4 marginal veins also present, secondary lateral
85. Typhonodorum
PELTANDREAE : TYPHONODORUM
247
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B
D
E
A
G
F
C
H
Plate 84. Peltandra. A, habit, rhizome cut through × 1/2; B, detail of leaf venation × 5; C, spadix × 1; D, synandrium, top view × 8; E, synandrium, side view × 8; F, gynoecium with associated staminodes, three quarter view × 8; G, gynoecium, longitudinal section × 8; H, berry ×
2. Peltandra virginica: A, Curtis 4572 (K); Cult. Kew 1969–19636 (Kew spirit collection 29047.739); B–G, Cult. Kew 1969–19636 (Kew spirit
collection 29047.739); H, Herb. Careyanum s.n. (K).
248
THE GENERA OF ARACEAE
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D
A
B
F
G
H
K
A
J
E
C
L
Plate 85. Typhonodorum. A, habit in × 1/30; B, habit in flower and fruit × 1/25; C, leaf × 1/5; D, detail of leaf venation × 4; E, spadix ×
2/3; F, staminodes from upper sterile male zone × 5; G, synandrium × 5; H, synandrode from lower sterile male zone × 5; J, gynoecium
with associated staminodes × 5; K, gynoecium, longitudinal section × 5; L, infructescence, spathe partly removed × 1/2. Typhonodorum
lindleyanum: A, 5497 (Kew slide collection); B, 4M 4.91 (Kew slide collection); C, Cult. Kew 1979–4434; D, Vaughn 445 (K); E–L, Cult.
Kew 1979–4434 (Kew spirit collection 29047.658); Lourance s.n. (Kew spirit collection 29047.356).
PELTANDREAE : TYPHONODORUM
249
26f -27 Tribes & Genera Acro 18/7/97 7:21 Page 250
and higher order venation densely parallel-pinnate. INFLORESCENCE: 1–2 in each floral sympodium. PEDUNCLE:
erect, bent downwards in fruit. SPATHE: erect, constricted
between tube and blade, tube convolute, oblong-ellipsoid,
green, persistent, blade longer than tube, narrowly boatshaped, acuminate, gaping at anthesis, cream-coloured,
marcescent, later deciduous. SPADIX: shorter than spathe,
sessile, free, differentiated into 4 zones, basal female zone
with staminodes scattered between gynoecia, separated from
male zone by narrower zone of sterile male flowers, male
zone thicker, terminal zone composed of sterile male flowers. FLOWERS: unisexual, perigone absent. MALE FLOWER:
4–6-androus, stamens connate into truncate synandrium,
connective very broad, thecae lateral, sessile, dehiscing by
short longitudinal slit. POLLEN: inaperturate, ellipsoid,
medium-sized (mean 45 µm.), exine subverrucate or
obscurely foveolate or punctate. LOWER STERILE MALE
FLOWERS: synandrode truncate, subhexagonal becoming
narrowly rhomboid to trapezoid towards male zone. UPPER
STERILE MALE FLOWERS: composed of 3–6 obpyramidal,
truncate staminodes, irregularly connate or merely crowded
together. FEMALE FLOWER: gynoecia surrounded by irregularly scattered, obpyramidal, truncate staminodes, ovary
shortly ovoid to globose, 1-locular, ovule 1(–2),
orthotropous, funicle thick, short, placenta basal, stylar
region very shortly attenuate, stigma rather broad, shallowly
3–6-lobed. BERRY: borne in subcylindric, pendent infructescence enclosed in persistent spathe tube, berries very large,
compressed-obovoid to -globose, bright yellow, pericarp
fleshy. SEED: large, compressed-obovoid, testa thin, ±
smooth, embryo very large, plumule exceptionally welldeveloped with several leaf primordia, endosperm absent.
See Plates 85, 126B.
CHROMOSOMES: 2n = 112.
DISTRIBUTION: 1 sp.; Comores, Madagascar, Mauritius,
Tanzania (Pemba, Zanzibar).
ECOLOGY: tropical wetland habitats; helophytes, freshwater
swamps, along rivers, coastal lagoons in brackish water,
forming huge populations.
86. Arisarum
250
THE GENERA OF ARACEAE
ETYMOLOGY: Greek typhôn (personification of stormy
winds) and doron (gift); a poetic name.
TAXONOMIC ACCOUNTS: Engler (1915), Bogner (1975),
Mayo (1985a).
Tribe Arisareae
C
Tribe Arisareae Dumortier, Fl. Belg. 162 (1827).
Laticifers simple, articulated; seasonally dormant, stem a tuber
or rhizome; leaves 1–3; petiole usually relatively long; primary lateral veins forming submarginal collective vein, higher
order venation reticulate; inflorescence 1, appearing with
leaves; spathe not constricted, tube margins connate, blade
fornicate, gaping; spadix with usually smooth, sterile, terminal appendix, female zone adnate to spathe, very short,
contiguous with male, male zone laxly flowered; flowers
unisexual, perigone absent; male flower 1-androus, filament
distinct, anther peltately attached, circular, thecae apically
confluent, dehiscing by 1 continuous slit, pollen ellipsoid, striate-reticulate; gynoecia 2–5, ovary 1-locular, ovules several,
orthotropous, placenta basal; endosperm copious.
86. Arisarum
Arisarum P. Miller, Gard. Dict. abr. ed., [121] (1754). LECTOTYPE: A. vulgare Targioni-Tozzetti (Arum arisarum L.,
see Nicolson in Taxon, 24: 467. 1975).
SYNONYMS: Arisaron Adanson, Fam. 2: 470 (1763);
Balmisa M. Lagasca, Gen. Sp. Pl. Nov. 17 (1816).
HABIT: small, seasonally dormant herbs, stem an ovoid to
cylindric tuber or slender rhizome (A. proboscideum) with
stolons. LEAVES: 1–2(–3). PETIOLE: often sparsely spotted,
sheath short. BLADE: cordate-sagittate to subhastate; primary lateral veins pinnate and also arising at petiole
insertion, forming submarginal collective vein, 2 marginal
C
26f -27 Tribes & Genera Acro 18/7/97 7:21 Page 251
F
A
B
C
D
G
E
J
H
K
Plate 86. Arisarum. A, habit × 2/3; B, spadix × 2; C, stamen × 15; D, gynoecium × 15; E, gynoecium, longitudinal section × 15; F, infructescence × 2; G, spadix × 2; H, habit × 2/3; J, spadix × 2; K, infructescence × 2. Arisarum proboscideum: A, Sievercori s.n. (K); B–E, Cult.
Boyce (Kew spirit collection 53920); F, Cult. Meikle (Kew spirit collection 28255); A. simorrhinum: G, Cult. Salmon (Kew spirit collection
53914); A. vulgare : H, Mitchell, Cheese & Watson 3880 (K); J, Cook & Keesing (Kew spirit collection 51085); K, Cult. Kew Marr 1996 (Kew
spirit collection 51128).
ARISAREAE : ARISARUM
251
26f -27 Tribes & Genera Acro 18/7/97 7:21 Page 252
veins also present, higher order venation reticulate. INFLORESCENCE: solitary, appearing with leaves. PEDUNCLE:
shorter or equalling leaf, often spotted. SPATHE: eventually
evanescent, tube erect, margins connate, cylindric to
subventricose, slightly constricted at apex, white or with
white to pale green longitudinal stripes, blade fornicate,
gaping, sometimes subtomentose, apex cuspidate or drawn
out into a very long, erect to twisted thread, greenish or
brownish or purple-brown. SPADIX: female zone adnate to
spathe, 2–5-flowered, contiguous with male zone, male zone
laxly flowered, extending for more than half spathe tube
length, terminal appendix naked, either stipitate with massive apical knob, or stipitate with thick, clavate, basally
truncate, fungoid, apical region, or not stipitate and slenderly
clavate. FLOWERS: unisexual, perigone absent. MALE
FLOWER: 1-androus, filament terete, as long or longer than
anther, anther peltately attached, circular, connective slender,
thecae apically confluent, dehiscing by single continuous slit.
POLLEN: pollen shed in amorphous mass, inaperturate, ellipsoid-elongate, medium-sized (mean 45 µm., range 43–46
µm.), exine striate to foveo-reticulate. FEMALE FLOWER:
ovary 1-locular, depressed-globose, ovules many,
orthotropous, funicle short, placenta basal, stylar region ±
abruptly narrowed, stigma small, subhemispheric. BERRY:
hemispheric, flattened at apex with elevated angled margins,
few-seeded, pericarp carnose-leathery, style base persistent.
SEED: ovoid, with large, irregularly conoid strophiole (aril),
testa longitudinally rugose, embryo terete, straight, axile,
endosperm copious. See Plates 86, 126C.
CHROMOSOMES: 2n = 28, 42, 56.
DISTRIBUTION: 3 spp.; Mediterranean Europe, Macaronesia:–
Albania, Algeria, Bosnia-Hercegovina, Croatia, Cyprus, Egypt,
France (incl. Corsica), Greece (incl. Crete), Israel, Italy (incl.
Sardinia, Sicily), Lebanon, Libya, Macedonia, Morocco,
Portugal (incl. Azores), Serbia, Slovenia, Spain (incl. Balearics,
Canary Is.), Syria, Tunisia, Turkey.
ECOLOGY: warm temperate scrub and woodland; geophytes,
on stony ground in macchie (“maquis”), between rocks or
under trees and shrubs.
ETYMOLOGY: Greek word arisaron (as used by Dioscorides
in reference to aris, aridos, the name of a small herb mentioned by Pliny, possibly Arisarum itself and aron (Arum)).
TAXONOMIC ACCOUNTS: Engler (1920a), Boyce (1990).
C
Tribe Ambrosineae
Tribe Ambrosineae Schott in Schott & Endlicher, Melet.
Bot. 16 (1832 “Ambrosinieae”).
Laticifers simple, articulated; very small, seasonally dormant,
stem a rhizomatous tuber; leaves several, blade ovate-elliptic, primary lateral veins mostly arising at petiole insertion,
arcuate, running into apex, higher order venation reticulate;
inflorescence 1, on recurved peduncle; spathe boat-shaped,
unconstricted externally, margins free, basal part convolute,
apical part narrowly gaping, rostrate, internally divided into
2 chambers, an upper, morphologically ventral one and a
lower, morphologically dorsal one; spadix shortly appendiculate, adnate to spathe by longitudinal, septum-like lateral
dilations, ventral chamber containing female zone, dorsal
chamber containing 8–10 male flowers arranged in 2 longitudinal rows; flowers unisexual, perigone absent; male flower
a 2-androus, sessile synandrium, thecae confluent, dehiscing
by single continuous slit, pollen exine striate-reticulate;
252
THE GENERA OF ARACEAE
gynoecium 1, ovary 1-locular, ovules many, orthotropous,
placenta basal, style long, curved, stigma discoid; berry manyseeded; seed subglobose, testa costate, strophiolate,
endosperm copious.
87. Ambrosina
Ambrosina Bassi, Ambrosina Nov. Pl. Gen. 3 (1763);
Bononiensi Sci. Inst. Acad. Comment. 5 (2): 82–86 (1766,
“1767”). TYPE: A. bassii L. (“Ambrosinia ”).
SYNONYM: [Ambrosinia L., Gen. pl., ed. 6, 579 (1764),
orth. var.].
HABIT: very small herb, seasonally dormant, stem a rhizomatous tuber. LEAVES: 2–4. PETIOLE: sheath short.
BLADE: ovate or ovate-elliptic, obtuse, often spotted; primary lateral veins 2–3 on each side, mostly arising at petiole
insertion, arcuate, running into apex, higher order venation
reticulate. INFLORESCENCE: solitary, lying horizontally on
ground. PEDUNCLE: short, hypogeal, elongating in fruit.
SPATHE: ellipsoid, boat-shaped, not constricted, basally convolute, gaping above, interior surfaces bearing hair-like
processes, stellate hairs occurring on inner and outer surfaces of ventral (pistillate) chamber, apex forming curved
beak. SPADIX: enclosed by the spathe, shortly appendiculate, adnate to internal wall of spathe by septum-like lateral
dilations thus forming two longitudinal chambers separating
male flowers from female; ventral chamber (held uppermost) containing single female flower, dorsal chamber (held
lowermost) containing usually 16 thecae arranged in two
parallel rows of 8 each. FLOWERS: unisexual, perigone
absent. MALE FLOWER: each row of 8 thecae represents 4
sessile stamens (see note), thecae oriented transversely,
opening by longitudinal slit. POLLEN: extruded in irregular
masses, inaperturate, ellipsoid-oblong, medium-sized (44
µm.), exine striate-reticulate, with narrow undulate striae in
“football” pattern, breaking up into verrucae at ends.
FEMALE FLOWER: ovary 1-locular, ovules many,
orthotropous, funicles rather long, placenta discoid, basal,
stylar region long, attenuate, curved towards spadix axis,
stigma discoid, flattened, held ± parallel to spadix axis.
BERRY: depressed-globose, many-seeded, style and old
87. Ambrosina
C
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G
B
C
A
D
E
F
Plate 87. Ambrosina. A, habit × 1; B, inflorescence, nearside half of spathe removed × 2; C, inflorescence, three quarter view, nearside
half of spathe removed × 2; D, stamens × 8; E, gynoecium × 8; F, gynoecium, longitudinal section × 8; G, infructescence, nearside half of
pericarp removed × 2. Ambrosina bassii: A, Besler s.n. (K); B–G, Bogner 2101 (Kew spirit collection K 57302).
stigma persistent, whitish with reddish tinge. SEED: subglobose to ellipsoid, testa costate with weak reticulation, brown,
hard, with large, white, conical strophiole (aril), embryo
straight, elongate, endosperm copious. See Plates 87, 126D.
CHROMOSOMES: 2n = 22.
DISTRIBUTION: 1 sp.; western Mediterranean Europe:–
Algeria, Italy (incl. Lampedusa Is., Sardinia, Sicily).
ECOLOGY: warm temperate scrub and woodland; geophytes,
usually in macchie (maquis) scrub, forest floor, humus
deposits between rocks or in open stony ground.
NOTES: The morphological interpretation of the male flower remains uncertain. Benzing (1969: Tafel 27.I) presented an
illustration which shows that in each longitudinal row, the
thecae are associated in pairs by their vascular supply. Both
Engler (1920a) and Benzing state that the male flowers are
2-androus. However, in our opinion the evidence for this
conclusion remains weak.
ETYMOLOGY: named after B. Ambrosini (1588–1657),
botanist at Bologna.
TAXONOMIC ACCOUNTS: Engler (1920a), Killian (1929,
1933), Benzing (1969).
C
Tribe Areae
Tribe Areae
Laticifers simple, articulated; minute to robust, seasonally
dormant, stem a subglobose to rhizomatous tuber; leaves
several (often 1 in Sauromatum), primary lateral veins of leaf
blade or lobes or leaflets forming submarginal collective
vein, higher order venation reticulate; inflorescence usually
1, appearing with or after leaves (except Sauromatum and
some Biarum spp.); spathe usually strongly constricted, tube
with convolute margins (partially to fully connate in
Sauromatum and in most Biarum spp.), blade gaping, erect
to reflexed; spadix with usually smooth, terminal, sterile
appendix; flowers unisexual, perigone absent; stamens usually free, connective slender, pollen exine spinose (except
Dracunculus, Biarum ditschianum; scabrous in Arum
korolkowii); ovary 1-locular, ovules orthotropous, style usually as broad as ovary (except some Biarum and Arisaema
spp.), stigma hemispheric; berry subglobose; seed usually
with rather large, fleshy strophiole (aril), testa usually rugosereticulate (except Sauromatum and some Biarum spp.),
endosperm copious.
C
88. Arum
Arum L., Sp. Pl. 964 (1753). LECTOTYPE: Arum maculatum
L. (see M.L. Green, Brit. Bot. 186. 1929).
SYNONYMS: [Aron Adanson, Fam. 2: 470 (1763), orth.
var.]; Gymnomesium Schott in Oesterr. bot. Wochenbl. 5: 17
(1855).
HABIT: seasonally dormant herbs, tuber hypogeal, subglobose or rhizomatous and horizontal. LEAVES: 3–4(–6) in each
sympodial unit. PETIOLE: sheath long to short. BLADE: cordate (A. pictum) or hastate-sagittate to sagittate; primary
lateral veins pinnate, forming submarginal collective vein, at
least 1 marginal vein also present, higher order venation
reticulate. INFLORESCENCE: 1, rarely 2 in each floral sympodium, usually appearing with leaves, rarely just before (A.
pictum), hidden within foliage or fully exposed above leaves.
PEDUNCLE: much shorter to much longer than petiole.
SPATHE: marcescent, usually strongly constricted between
tube and blade, rarely not, tube convolute, cylindric to ellipsoid, blade ovate- or oblong-lanceolate to lanceolate, ±
acuminate, at anthesis erect and boat-shaped or widely
expanded or patent and ± revolute. SPADIX: shorter to longer
than spathe, sessile, female zone cylindric, interstice sepa-
AREAE : ARUM
253
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rating male and female zones usually short, rarely absent,
usually covered with sterile flowers (pistillodes), rarely naked,
male zone cylindric, conoid, ellipsoid or subglobose, interstice separating appendix and male zone usually covered
with sterile flowers (staminodes), rarely absent, terminal sterile appendix usually stipitate, then gradually or suddenly
dilated into a conoid or cylindric club, sometimes slender.
FLOWERS: unisexual, perigone absent. MALE FLOWER: 3–4androus, stamens free, filaments very short but distinct,
connective slender, thecae shortly obovoid, opposite or subopposite, dehiscing by apical pore-like slit, rarely porose (A.
pictum). POLLEN: usually presented in a loose, powdery
mass, sometimes extruded in strands (A. pictum, A. nigrum),
grains inaperturate, spherical to subspheroidal, medium-sized
(mean 32 µm., range 29–34 µm.), exine spinose, rarely
scabrous (A. korolkowii). STERILE FLOWERS: (staminodes
and pistillodes) consisting of basal, ± hemispheric, swollen,
verrucose to smooth portion bearing usually one (sometimes
more) erect, ± straight, subulate to filiform processes.
FEMALE FLOWER: gynoecium cylindric, ovary 1-locular,
ovules 6–more, orthotropous, lageniform, biseriate, funicle
short, placenta parietal to subbasal, stylar region short, as
broad as ovary or absent, stigma subhemispheric, exuding
nectar droplet at anthesis. BERRY: obovoid, pericarp juicy,
many-seeded, bright glossy orange-red. SEED: ellipsoid to
ovoid, testa rugose, especially towards base, with large, succulent obconic strophiole, embryo axile, straight, endosperm
copious. See Plates 88, 127A.
CHROMOSOMES: 2n = 28, 42, 56, 70, 84.
DISTRIBUTION: 25 spp.; Central Asia, Europe, Macaronesia,
Mediterranean, Middle East:– Afghanistan, Albania, Algeria,
Andorra, Armenia, Austria, Azerbaijan, Belgium, Belorussia
(S), Bosnia–Hercegovina, Bulgaria, China (Tien Shan),
Croatia, Cyprus, Czech Republic, Denmark, France (incl.
Corsica), Georgia, Germany, Greece (incl. islands), Hungary,
India (NW), Iran, Iraq, Ireland, Israel, Italy (incl. Sardinia,
Sicily), Jordan, Kazakhstan, Kirghizia, Lebanon, Libya,
Liechtenstein, Luxembourg, Macedonia, Moldavia, Morocco,
Nepal (W), Netherlands, Pakistan, Poland, Portugal (incl.
Azores, Madeira), Romania, Russia (far S), San Morino,
Serbia, Slovak Republic, Slovenia, Spain (incl. Canary Is.,
Balearics), Sweden (S), Switzerland, Syria, Tajikistan, Tunisia,
Turkey, Turkmenestan, Ukraine (S), United Kingdom (incl.
Channel Is.), Uzbekistan.
88. Arum
254
THE GENERA OF ARACEAE
ECOLOGY: temperate and warm temperate woodland, up
to 4400m alt.; geophytes, forest floor, hedges, orchards,
stony open ground, along rivers, open scrub, pastures,
abandoned areas.
NOTES: Boyce (1989, 1993) recognized 2 subgenera, subgen.
Arum (with 2 sections and 6 subsections) and subgen.
Gymnomesium. Arum italicum is naturalized in Argentina
and New Zealand.
ETYMOLOGY: Latin form of the classical Greek name aron.
TAXONOMIC ACCOUNTS: Engler (1920a), Arrigoni et al.
(1982), Boyce (1989, 1993a,1995).
C
89. Eminium
Eminium (Blume) Schott, Aroideae 16 (1855, “1853”). LECTOTYPE: E. spiculatum (Blume) Schott (Arum spiculatum
Blume; see Nicolson 1967, p. 516).
SYNONYM: Helicophyllum Schott, Aroideae 20 (1855,
“1853”), non Bridel (1827).
HABIT: medium-sized, seasonally dormant herbs, tuber subglobose. LEAVES: 3–6 (–8). PETIOLE: sheath relatively long.
BLADE: oblong-elliptic (E. lehmannii, E. regelii), linear- to
auriculate-hastate, or pedatifid-pedatisect with lobes of posterior divisions held ± erect in a spiral on the twisted basal
ribs; primary lateral veins of lobes pinnate, forming submarginal collective vein, higher order venation reticulate.
INFLORESCENCE: solitary, appearing with leaves. PEDUNCLE: much shorter than petiole of subtending leaf, apex often
greatly thickened. SPATHE: marcescent, tube with convolute
margins, subventricose to oblong, blade oblong or ovateoblong, erect, inner surface sometimes densely
rugose-puckered. SPADIX: sessile, slender, shorter than
spathe, female zone short-cylindric, separated from male zone
by longer zone bearing usually scattered sterile flowers, male
zone ellipsoid to cylindric, shorter, equalling or longer than
female, appendix usually relatively short, elongate-clavate,
stoutly to narrowly cylindric, rugose or smooth. FLOWERS:
unisexual, perigone absent. MALE FLOWER: 2-androus, stamens free, anthers subsessile to sessile, connective slender,
thecae oblong-ellipsoid, dehiscing by apical slit. POLLEN:
presented in a loose, powdery mass, not extruded in strands,
grains inaperturate, spherical or subspheroidal, medium-sized
89. Eminium
26f -27 Tribes & Genera Acro 18/7/97 7:22 Page 255
K
C
F
B
J
E
G
H
D
AA
Y
X
A
U
Z
V
L
M
N
P
Q
R
S
T
W
Plate 88. Arum. A, habit × 1/5; B, tuber × 2/3; C, tuber × 2/3; D, leaf × 1; E, detail of leaf venation next to midrib × 6; F, detail of leaf venation near margin × 6; G, leaf × 2/3; H, inflorescence, front of lower spathe removed × 2/3; J, spathe, front view × 2/3; K, spathe, side view
× 2/3; L, spadix × 2/3; M, detail of fertile portion of spadix × 2; N, spadix × 2/3; P, detail of fertile portion of spadix × 2; Q, spadix × 2/3; R,
detail of fertile portion of spadix × 2; S, spadix × 2/3; T, detail of fertile portion of spadix × 2; U, stamen × 10; V, stamens, lower one longitudinally sectioned × 10; W, gynoecia, upper one longitudinally sectioned × 10; X, pistillode × 15; Y, staminode × 15; Z, infructescence × 2/3;
AA, seed × 2. Arum maculatum: A, Boyce s.n. (Kew slide collection); A. alpinum: B, Cook & Keesing 56 (Kew spirit collection 51396); A.
concinnatum: C, L–M, U, X–Y, Boyce 10 (Kew spirit collection 53952); A. rupicola var. rupicola: D–F, Sintenis 5575 (K); A. italicum subsp.
italicum: G, Herb. Churchill s.n. (K); A. orientale subsp. orientale: H, Cult. Tucker (Kew spirit collection 49773); A. rupicola subsp. rupicola: J, Boyce 87 (Kew spirit collection 51615); A. creticum: K, N–P, Cult. Kew (Kew spirit collection 51368); A. orientale subsp. orientale:
Q–R, Cult. Tucker (Kew spirit collection 49773); A. pictum: S–T, V–W, Ferguson & Ferguson 4126, Cult. Kew 1985–01888 (Kew spirit collection 51818); A. italicum subsp. italicum: Z, photo 1336 (Kew slide collection); A. alpinum: AA, Cook & Keesing 56 (Kew spirit collection 51898).
AREAE : ARUM
255
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B
C
L
D
A
F
E
G
H
M
N
K
J
Plate 89. Eminium. A, habit × 1/3; B, seedling showing contractile root × 2/3; C, detail of fertile portion of spadix × 1 1/2; D, habit × 2/3;
E, spadix × 1 1/2; F, stamen × 15; G, gynoecium × 15; H, gynoecium, longitudinal section × 15; J, inflorescence × 2/3; K, spadix × 1 1/2; L,
stamen × 15; M, gynoecium × 15; N, gynoecium, longitudinal section × 15. Eminium albertii: A, Furse 7390 (K); Gibbons & Gibbons 47 (K);
B, Gibbons & Gibbons 47 (K); C, Grey-Wilson & Hewer 765 (Kew spirit collection 29047.120); E. koenenianum: D, Willdenowia 20: 47, f.4
(1991); E–H, Koenen 32*89 (Kew spirit collection 55074 & 59044); E. spiculatum subsp. spiculatum: J, Boyce 197 (Kew spirit collection 51645
& Kew slide collection); K–N, Boyce 197 (Kew spirit collection 51645).
256
THE GENERA OF ARACEAE
26f -27 Tribes & Genera Acro 18/7/97 7:23 Page 257
(mean 44 µm.; 15–20 µm in E. koenenianum), exine spinose.
STERILE FLOWERS: composed of subulate, sometimes flattened, patent, straight to slightly curved processes. FEMALE
FLOWER: ovary ellipsoid-obovoid, 1-locular, ovules 2,
orthotropous, funicle short, placenta basal to subbasal, stylar
region short to inconspicuous, stigma hemispheric. BERRY:
subglobose, 1(–2) seeded. SEED: obnapiform to subglobose,
testa leathery, rugose, with large strophiole, embryo small,
elongate, endosperm copious. See Plates 89, 127B.
CHROMOSOMES: 2n = 24, 28.
DISTRIBUTION: 8 spp.; Middle East, south central Asia:
Afghanistan, Egypt, Iran (N), Iraq (N), Israel, Jordan,
Kazakhstan, Kirghizia, Lebanon, Syria, Tajikistan, Turkey,
Turkmenestan, Uzbekistan.
ECOLOGY: warm temperate and subtropical habitats in fields,
savannas, semideserts, deserts; geophytes, stony or sandy
ground, consolidated sand.
ETYMOLOGY: ancient name eminion, mentioned by
Dodoens (1574).
TAXONOMIC ACCOUNTS: Engler (1920a), Riedl (1963, 1969,
1985), Lobin & Boyce (1991).
C
90. Dracunculus
Dracunculus P. Miller, Gard. Dict., Abr. ed., [455] (1754).
LECTOTYPE: D. vulgaris Schott (see Nicolson 1975, p. 467).
SYNONYMS: Anarmodium Schott in Bonplandia 9: 368
(1861); Dracontium J. Hill, Brit. Herb. 336 (1756, non L.
1753).
HABIT: large, seasonally dormant herbs, tuber subglobose,
stoloniferous as well in D. canariensis. LEAVES: few. PETIOLE: sheath very long, spotted or not, tightly convolute
around peduncle forming substantial erect pseudostem.
BLADE: deeply pedatifid; primary lateral veins of each lobe
pinnate, forming submarginal collective vein, higher order
venation reticulate. INFLORESCENCE: solitary, appearing
with leaves. PEDUNCLE: shorter than petiole. SPATHE:
marcescent, constricted, tube with convolute margins, erect,
thick-walled, oblong-ellipsoid, shorter than blade, blade
ovate-lanceolate, acuminate, expanded, deep purple or
white, eventually bent backwards. SPADIX: subequal to
spathe, female zone ± sessile, cylindric to conic, contiguous
with male zone, male zone ellipsoid-cylindric, separated
from appendix by a short zone of subulate staminodes,
appendix long, long-stipitate, then elongate-conoid.
FLOWERS: unisexual, perigone absent. MALE FLOWER: 3–4androus, stamens quadrate, filaments distinct, connate at
base, connective slender and prominulent, thecae shortly
ellipsoid, dehiscing by apical pore. POLLEN: extruded in
strands, inaperturate, ellipsoid to spheroidal, medium-sized
(mean 45 µm.), exine verrucate. FEMALE FLOWER: ovary
ellipsoid, 1-locular, ovules few, orthotropous, placentae apical and basal, stylar region shortly conic, stigma hemispheric.
BERRY: obovoid, few-seeded, red-orange. SEED: globoseovoid, testa rugose, embryo axile, short, endosperm copious.
See Plates 90, 127C.
CHROMOSOMES: 2n = 28.
DISTRIBUTION: 2 spp.; Mediterranean Europe,
Macaronesia:– Albania, Bosnia–Hercegovina, Bulgaria,
Croatia, Greece (incl. Crete and islands), Italy (incl. Sardinia,
Sicily), Macedonia, Portugal (incl. Azores, Madeira), ? Serbia,
Slovenia, Spain (Canary Is.), Turkey.
ECOLOGY: temperate and warm temperate scrub, woodland, macchie, olive groves, chestnut forest; geophytes, under
trees and shrubs, also stony open ground.
NOTES: The verrucate pollen exine of Dracunculus is unique
in the tribe. The other genera have a spinose, spinulose or
rarely smooth exine. The seed of Dracunculus lacks the
characteristic strophiole found in other genera of the tribe.
ETYMOLOGY: ancient name, Latin draco (dragon, snake)
and suffix -unculus (diminutive).
TAXONOMIC ACCOUNTS: Engler (1920a), Amaral Franco,
Webb & Prime (1980), Boyce (1994).
C
91. Helicodiceros
Helicodiceros Schott ex K. Koch in Index Sem. Hort. Berol.
1855, Appendix, p. 2 (1856), nom. cons. TYPE: H. crinitus K.
Koch, nom. illeg. (Dracunculus crinitus Schott, nom. illeg.,
Arum muscivorum L. f., H. muscivorus (L.f.) Engler).
SYNONYM: Megotigea Rafinesque, Fl. Tell. 3: 64 (1837,
“1836”), nom. rej.
HABIT: seasonally dormant herb, tuber depressed-globose.
LEAVES: several. PETIOLE: variously spotted, sheath long,
90. Dracunculus
AREAE : HELICODICEROS
257
26f -27 Tribes & Genera Acro 18/7/97 7:23 Page 258
B
G
J
L
K
H
D
A
E
F
C
Plate 90. Dracunculus. A, habit × 1/6; B, leaf × 1/3; C, detail of spadix fertile portion and appendix base × 1; D, stamen × 10; E, gynoecium × 10; F, gynoecium, longitudinal section × 10; G, infructescence × 2/3; H, spadix × 1; J, stamen × 10; K, gynoecium × 10; L, gynoecium,
longitudinal section × 10. Dracunculus vulgaris: A, Fleming s.n. (Kew slide collection); B, Cult. Cheston (K); C–F, Boyce 19 (Kew spirit
collection 51381); G, Cult. Kew (Kew spirit collection 25760); Zabeau 11/65 (Kew slide collection); D. canariensis: H–L, Cult. Boyce (Kew
spirit collection 29047.679).
258
THE GENERA OF ARACEAE
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B
E
A
F
G
C
D
Plate 91. Helicodiceros. A, habit × 1/3; B, detail of hairs on spathe limb interior × 1; C, spadix × 2/3; D, detail of spadix fertile portion and
appendix base × 1; E, stamen × 10; F, gynoecium × 10; G, gynoecium, longitudinal section × 10. Helicodiceros muscivorus: A, Boyce 36 (Kew
slide collection); B–G, Boyce 36 (Kew spirit collection 29047.638).
91. Helicodiceros
forming loose pseudostem. BLADE: deeply pedatifid, anterior division oblong, lobes of posterior divisions tightly
spiralled on basal ribs and thus held ± erect; primary lateral
veins of each lobe pinnate, weakly differentiated, forming
submarginal collective vein, higher order venation reticulate.
INFLORESCENCE: solitary, appearing with leaves. PEDUNCLE: much shorter than petiole. SPATHE: spotted on outer
surface, constricted between tube and blade, tube with convolute margins, erect, green, thick, subcylindric, blade sharply
bent backwards at constriction, large, oblong-ovate, widely
spreading, pale purple, inner surface covered with purple
hairs. SPADIX: shorter than spathe, bent backwards at spathe
constriction, female zone sessile to shortly stipitate, subcylindric, sterile zone separating male and female zones
short, covered with subulate pistillodes or naked, male zone
subcylindric to ellipsoid, shorter than or subequal to female,
appendix vermiform, much longer than rest of spadix, weakly
stipitate, thicker at middle, attenuate towards apex and base,
± lying on spathe blade, entirely covered with upwardly
curved, setiform staminodial processes becoming gradually
larger and subulate towards appendix base. FLOWERS: unisexual, perigone absent. MALE FLOWER: 2–3-androus,
AREAE : HELICODICEROS
259
26f -27 Tribes & Genera Acro 18/7/97 7:24 Page 260
stamens free, anthers sessile, connective slender, inconspicuous, thecae ± ellipsoid, dehiscing by broad apical slit.
POLLEN: extruded in strands, inaperturate, ± spherical, exine
spinose. FEMALE FLOWER: ovary 1-locular, ovules up to 6,
orthotropous, placentae 2, apical placenta with 3–4 ovules
and basal placenta with 1–2 ovules, stylar region as broad or
broader than ovary, stigma subhemispheric. BERRY: obovoid
to ellipsoid, bearing small stigma remnant, (1–)2–3-seeded,
orange. SEED: borne on either one or both placentae, broadly
ovoid, with yellowish strophiole, testa leathery, strongly reticulate, pale brown when fresh, embryo axile, elongate,
endosperm copious. See Plates 91, 127D.
CHROMOSOMES: 2n = 56.
DISTRIBUTION: 1 sp.; western Mediterranean Europe:–
France (Corsica), Italy (Sardinia), Spain (Balearic Islands).
ECOLOGY: warm temperate habitats; geophytes, in limestone and granite rock crevices beside the sea, rarely on
stony ground.
ETYMOLOGY: Greek “helix, helicos” (spiral), “dis” (twice)
and “keras” (horn), referring to the two basal lobes of the leaf
that are twisted and erect like horns.
TAXONOMIC ACCOUNTS: Arcangeli (1884), Engler (1920a);
Arrigoni et al. (1982, as Dracunculus muscivorus), Boyce
(1994).
C
92. Theriophonum
Theriophonum Blume, Rumphia 1: 127 (1837, “1835”).
TYPE: T. crenatum (R. Wight) Blume (Arum crenatum R.
Wight).
SYNONYMS: Tapinocarpus Dalzell in Hooker’s J. Bot.
Kew Gard. Misc. 3: 345 (1851); Calyptrocoryne Schott in
Oesterr. bot. Wochenbl. 7: 262 (1857); Pauella Ramamurthy
& Sebastine in Bull. Bot. Surv. India 8: 348 (1967).
HABIT: small, seasonally dormant herbs, tuber small,
depressed-subglobose. LEAVES: several. PETIOLE: sheath relatively long. BLADE: sagittate-hastate or hastate, sometimes
linear-lanceolate or oblong-ovate; primary lateral veins pinnate, forming submarginal collective vein, 1–2 distinct
marginal veins also present, higher order venation reticulate. INFLORESCENCE: solitary, appearing with the leaves.
PEDUNCLE: usually short, erect in flower, deflexing in fruit.
SPATHE: marcescent, constricted between tube and blade,
tube convolute, blade much longer than tube, erect and gaping to spreading, or sometimes ± reflexed. SPADIX: sessile,
shorter or subequal to spathe, female zone few-flowered,
very short, separated from male by axis partly or completely
covered with sterile flowers, sterile flowers either basal, central or at apex of sterile zone, male zone cylindric, sometimes
with zone of sterile flowers above, appendix stipitate or not,
erect, shorter or much longer than rest of spadix, cylindric,
elongate-conoid to very long-subulate. FLOWERS: unisexual, perigone absent. MALE FLOWER: 1–2-androus, stamens
free, anthers subsessile, connective slender, sometimes elongated and prominent, thecae ovoid, dehiscing by apical pore
or broad slit. POLLEN: inaperturate, spherical, medium-sized
(mean 25 µm.), exine spinose. STERILE FLOWERS: spreading, somewhat decurved or suberect, long, slender and
filiform to shorter and subulate. FEMALE FLOWER: gynoecia
oriented vertically, ovary ellipsoid to obovoid, 1-locular,
ovules 3–9 (or more), orthotropous, funicle short, placentae
2, apical and basal, stigma ± sessile, discoid-hemispheric,
sometimes rather massive with central depression. BERRY:
260
THE GENERA OF ARACEAE
92. Theriophonum
ovoid to ellipsoid, few-seeded. SEED: broadly ovoid to ellipsoid, apiculate, strophiolate, testa smooth to rugose, embryo
axile, elongate, endosperm copious. See Plate 92.
CHROMOSOMES: 2n = 16 (14, 18).
DISTRIBUTION: 5 spp.; India, Sri Lanka.
ECOLOGY: tropical forest; geophytes, forest floor, grassy
places, ditches, damp sites on rocky, lateritic soil.
ETYMOLOGY: Greek name theriophonon from therion (wild
beast) and phenô (I slay); means “beast-slayer”.
TAXONOMIC ACCOUNTS: Engler (1920a), Sivadasan &
Nicolson (1982).
93. Typhonium
Typhonium Schott in Wiener Z. Kunst 1829 (3): 732 (1829).
LECTOTYPE: T. trilobatum (L.) Schott (Arum trilobatum L.;
see Nicolson in Taxon 16: 519. 1967).
SYNONYMS: Desmesia Rafinesque, Fl. Tell. 3: 63 (1837,
“1836”); Heterostalis (Schott) Schott in Oesterr. bot. Wochenbl.
7: 261 (1857).
HABIT: very small to medium-sized, seasonally dormant or
evergreen, rarely pubescent (T. hirsutum) or glandularpubescent herbs, tuber globose, subglobose or irregular,
sometimes rhizomatous or stoloniferous, rarely an epigeal
stem (T. fultum). LEAVES: few to several. PETIOLE: apex and
middle portion rarely tuberculate, sheath rather short.
BLADE: usually cordate-sagittate, sagittate to hastate, trifid,
pedatifid or pedatisect, rarely linear, narrowly lanceolate,
elliptic-oblong or cordate, apex rarely tuberculate; primary
lateral veins of blade or lobes pinnate, forming submarginal
collective vein, 1–2 marginal veins also present, higher order
venation reticulate. INFLORESCENCE: solitary, appearing
with or without (T. hayatae) or after the leaves. PEDUNCLE:
shorter than petiole. SPATHE: constricted between tube and
blade, tube with convolute or rarely basally connate (T. hirsutum) margins, persistent or rarely evanescent (T.
nudibaccatum), blade eventually bending backwards from
constriction, broadly ovate to lanceolate, ± acuminate, usually purple, rarely white within, tube persistent, blade
marcescent. SPADIX: sessile, shorter, subequal or much
longer than spathe, female zone cylindric, subconic to subglobose, separated from male zone by rather long axis
C
26f -27 Tribes & Genera Acro 18/7/97 7:24 Page 261
F
H
C
M
A
J
B
K
G
L
D
E
Plate 92. Theriophonum. A, habit × 2/3; B, detail of fertile portion of spadix and appendix base × 3; C, stamen with prominent connective ×
15; D, gynoecium × 15; E, gynoecium, longitudinal section × 15; F, infructescence × 1; G, habit × 1; H, leaf × 1; J, leaf × 1; K, detail of fertile portion of spadix and appendix base × 4; L, detail of fertile portion of spadix and appendix base × 3; M, stamen × 15. Theriophonum minutum: A,
Barnes 699 (K); Barnes 700 (K); Balasubramanian 2047 (K); Bogner s.n. (Kew slide collection); B–E, Barnes 698 (K & Kew spirit collection 58090);
F, Nicolson 4266 (K); T. sivaganganum: G–K, Rajagopalan RHT 30294 (K & Kew spirit collection 58131); T. infaustum: L–M, Barnes 1333 (K &
Kew spirit collection 58071).
AREAE : THERIOPHONUM
261
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H
J
K
E
C
A
B
D
G
F
Plate 93. Typhonium. A, spadix × 1 1/2; B, habit × 1/2; C, leaf × 1/2; D, spadix × 1 1/2; E, infructescence × 2/3; F, habit, part of petiole
removed × 1/2; G, detail of fertile portion of spadix × 1 1/2; H, stamen × 10; J, gynoecium, side view × 10; K, gynoecium, longitudinal section × 10. Typhonium brownii: A, Thomson 2360 (Kew spirit collection 57319); T. hirsutum: B, comm. Mayo ‘Arisaema 1’ (Kew spirit
collection 29047.710); T. trilobatum: C, D, Hay 2045 (Kew spirit collection 55956); E, Walker s.n. (K); T. giganteum: F, Cult. Cambridge Bot.
Gard. (K), Henry 6537 (K); Hetterscheid H.AR. 31 (Kew spirit collection 57592); G–K, Hetterscheid H.AR. 31 (Kew spirit collection 57592).
262
THE GENERA OF ARACEAE
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NOTES: Some species are weedy and naturalized in various
parts of the world outside Asia in tropical, subtropical and
warm temperate regions. Sriboonma, Murata & Iwatsuki
(1994) recognized 5 sections:– sect. Hirsuta, sect. Diversifolia,
sect. Pedata, sect. Gigantea, and sect. Typhonium.
ETYMOLOGY: cited by Dodoens (1574) as Greek Typhonion,
an ancient plant name; Typhon, the youngest child of Gaia,
the Greek Earth goddess, was a beast, half man, half reptile,
later slain by Zeus (A. Hay pers. comm.)
TAXONOMIC ACCOUNTS: Engler (1920a), Nicolson &
Sivadasan (1981), Sivadasan (1982), Bogner (1988b), Murata
(1990b), Murata & Mayo (1991), Hay (1993a), Sriboonma,
Murata & Iwatsuki (1994).
C
94. Sauromatum
93. Typhonium
covered either entirely or only in basal part with sterile flowers of various shapes, rarely with sterile flowers above male
flowers, male zone cylindric to ellipsoid, usually densely but
rarely sparsely flowered (T. albispathum), appendix usually
shortly stipitate, rarely with disc-like extension at the base or
sessile (T. hirsutum), smooth, conoid to extremely slender
and filiform-subulate, usually long-exserted. FLOWERS: unisexual, perigone absent. MALE FLOWER: 1–3-androus but
usually 1-androus, stamens free or sometimes ± connate,
anthers subsessile, connective slender, sometimes prominulent, thecae ovoid to ellipsoid, dehiscing by pore or lateral
slit extending to the middle or nearly to the base and confluent apically. STERILE FLOWERS: either all similar or
diverse in the same spadix, capitate, clavate to spathulate,
cylindric, filiform or subulate, rarely stout and flattened at the
tip, or reduced to verrucae, straight to flexuose, suberect,
spreading or decurved. POLLEN: extruded in amorphous
mass, inaperturate, spherical to subspheroidal, medium-sized
(mean 32 µm., range 28–36 µm.), exine spinose (spines very
obtuse in e.g. T. trilobatum). FEMALE FLOWER: gynoecia oriented horizontally or vertically, ovary ovoid, ellipsoid or
obovoid, 1-locular, ovules 1–3, orthotropous, funicle short,
placenta basal, stigma sessile, discoid-hemispheric. BERRY:
ovoid, 1- or rarely 2-seeded, orange-red, green or white.
SEED: globose to obnapiform, testa thin, rugulose to smooth,
strophiolate, embryo axile, elongate, straight, endosperm
copious. See Plates 93, 128A.
CHROMOSOMES: 2n = 16, 18, 20, 26, 36, 52, 54, 65, >100 (14).
DISTRIBUTION: 37 spp.; tropical south, southeast and east
Asia, Malay Archipelago, Australasia:– Australia, Bangladesh,
Bhutan, Burma, Cambodia, Caroline Is., China (incl. Taiwan,
Tibet), India, Indonesia (Borneo, Irian Jaya, Java, Moluccas,
Sumatra, Timor), Japan, Laos, Malaysia (Borneo, Peninsula),
Mariana Is., Mongolia, Nepal, Pakistan, Papua New Guinea,
Philippines, Singapore, Sri Lanka, Thailand, Vietnam.
Naturalized in Brazil (Northeast, Southeast), Comores, Cuba,
Ghana, Ivory Coast, Madagascar, Martinique, Mauritius, South
Africa, Surinam, Tanzania (Zanzibar), Trinidad, Venezuela,
ECOLOGY: warm temperate, subtropical and tropical humid
and seasonal forests, secondary forest, cultivated land; geophytes, forest floor, among rocks, wet sites, streamsides,
grassy places.
Sauromatum Schott in Schott & Endlicher, Melet. Bot. 17
(1832). LECTOTYPE: S. guttatum Schott (= S. venosum
(Aiton) Kunth, Arum guttatum Wallich 1831, non Salisbury
1796; see Nicolson 1967).
SYNONYMS: [Stauromatum Endlicher, Ench. 128 (1841),
orth. var.]; Jaimenostia Guinea & Gómez-Moreno in Guinea,
Ensayo Geobot. 248 (1946) & in Anales Jard. Bot. Madrid 6
(2): 465 (1946).
HABIT: small to medium-sized, seasonally dormant herbs,
tuber subglobose or depressed-globose, sometimes large.
LEAVES: usually solitary, rarely up to 3. PETIOLE: often spotted, sheath very short. BLADE: deeply pedatifid to pedatisect;
primary lateral veins of lobes pinnate, forming submarginal
collective vein, 1–2 marginal veins also present, higher order
venation reticulate. INFLORESCENCE: solitary, appearing with
or without leaves, borne at ground level. PEDUNCLE: very
short. SPATHE: marcescent, slightly constricted between tube
and blade, tube with connate margins, ± cylindric and usually
somewhat ventricose basally, blade much longer, narrowly
oblong-lanceolate, erect at first then reflexed and spiralled-revolute, margins undulate, conspicuously spotted on inner
surface. SPADIX: subequal to spathe, free, sessile, female
zone cylindric, separated from male zone by much longer axis
bearing sterile flowers in lower part and naked above, male
zone short, cylindric, appendix elongated, very long-exserted,
relatively slender, cylindric, smooth, obtuse, suberect then
somewhat forward-curving. FLOWERS: unisexual, perigone
absent. MALE FLOWER: few-androus, stamens free, anthers ±
sessile, somewhat compressed, connective slender, thecae
oblong-obovoid, dehiscing by broad, apical slit. POLLEN:
extruded in amorphous mass, inaperturate, spherical to subspheroidal, medium-sized (mean 33 µm.), exine spinose.
STERILE FLOWERS: consisting of distant, patent, terete, filiform, or clavate staminodes, apex rounded to obliquely
truncate-disciform. FEMALE FLOWER: gynoecium subcylindric, ovary 1-locular, ovules 1–4, orthotropous, funicle very
short, placenta basal, stylar region shortly attenuate or ± as
broad as ovary, stigma discoid-hemispheric. BERRY: obpyramidal, red-purple, darker and corrugated at apex, densely
congested in subglobose, sometimes partly hypogeal
infructescence. SEED: obnapiform, testa thin, dark-spotted,
smooth to rough, strophiole present, embryo axile, elongate
and curved, endosperm copious. See Plates 94, 128B.
CHROMOSOMES: 2n = 26, 52, 104.
DISTRIBUTION: 2 spp.; tropical Africa, Arabian peninsula,
tropical and subtropical southern Asia:– Angola, Bangladesh,
Bhutan, Burma, Cameroon, Central African Republic, China
AREAE : SAUROMATUM
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B
A
L
M
D
N
Q
P
C
K
J
E
F
G
H
Plate 94. Sauromatum. A, habit in flower × 1/5; B, habit × 1/5; C, leaf × 2/3; D, inflorescence × 2/3; E, spadix × 1; F, stamen × 20; G, gynoecium × 20; H, gynoecium, longitudinal section × 20; J, tuber in section, petiole base and mature infructescence × 1/2; K, juvenile plant ×
1/2; L, inflorescence × 2/3; M, spadix × 1; N, stamen × 30; P, gynoecium × 30; Q, gynoecium, longitudinal section × 30. Sauromatum venosum: A, Barnes 1617; B, Andrews 6/80 (Kew slide collection); C, Andrews 27/6/82 (Kew slide collection); D, Robertson p/8/35/5 (Kew slide
collection); E–H, Cult. Maw (Kew spirit collection 29047.122); J, Jarrett & Saldanha HFP 736 (K), Kultan s.n. (Kew spirit collection 6915);
K, Aitchison 268 (K); S. brevipes: L–M, Templar s.n. (K); N–Q, Templar s.n. (Kew spirit collection 47636).
264
THE GENERA OF ARACEAE
26f -27 Tribes & Genera Acro 18/7/97 7:25 Page 265
94. Sauromatum
(Tibet, Yunnan), Equatorial Guinea (Bioko) Ethiopia, India,
Kenya, Malawi, Nepal, Pakistan, Saudi Arabia, Tanzania,
Uganda, Yemen Republic, ?Zaire, Zambia.
ECOLOGY: tropical upland forest and grassland; geophytes
or occasionally epiphytes, shady, humid sites, also in humus
deposits on rocks.
NOTES: Differs from Typhonium only in the consistently
fused margins of the spathe tube and the curved embryo.
ETYMOLOGY: Greek sauros (lizard) and shortened form of
chrômaton (coloured); refers to lizard-like colour of the
petiole.
TAXONOMIC ACCOUNTS: Engler (1920a), Sivadasan (1982),
Mayo (1985a).
C
95. Lazarum
Lazarum A. Hay in Bot. J. Linn. Soc. 109 (3): 427–434 (1992).
TYPE: L. mirabile A. Hay
HABIT: very small, seasonally dormant herb; tuber subglobose, whitish. LEAVES: 1–3, appearing after flowering, dark
blueish green, subtended by deliquescent cataphylls. PETIOLE: sheath relatively long. BLADE: elliptic, base obtuse,
apex apiculate; midrib distinct, primary lateral veins pinnate,
running ± arcuately into margin near apex, marginal vein present, higher order venation reticulate. INFLORESCENCE:
solitary, subtended by long cataphylls, appearing before the
leaves. PEDUNCLE: very short, elongating in fruit. SPATHE:
marcescent, slightly constricted at position of an annular septum through which the spadix passes and which separates
the male zone from the female zone forming two chambers,
swelling again for a short distance above the constriction;
tube ± broadly ellipsoid, margins connate, not persistent in
fruit; blade narrowly lanceolate, sharply bent up, erect, margins inrolled. SPADIX: sessile, only slightly longer than
spathe, female flowers free, 5–7 in a single whorl, zone of
sterile flowers contiguous with female zone, male zone separated from zone of sterile flowers by naked axis which
passes through the central aperture of the spathe septum,
male flowers thus situated in the upper spathe chamber;
appendix vermiform, slightly exceeding spathe, smooth,
emerging from the mouth of the spathe tube and then
upturned. FLOWERS: unisexual, perigone absent. MALE
FLOWER: 2-androus, stamens free, anthers sessile, thecae
opening by apical pore. POLLEN: inaperturate, ellipsoid,
medium-sized (36–40µm. × 28–32µm.), exine spinose, spinulae 1.4– 1.6µm. long and apex somewhat rounded. STERILE
FLOWERS: slender, cylindric, obtuse, ascending at base, then
recurved and appressed against the wall of spathe tube.
FEMALE FLOWER: lageniform, ovary ovoid, 1-locular, ovule
1, orthotropous, placenta basal, stylar region short, attenuate,
stigma subhemispheric. BERRY: ovoid, 1-seeded, minutely
beaked at apex, reddish, infructescence with long peduncle,
with 5–7 berries in a whorl. SEED: ovoid to subglobose,
micropyle prominent, strophiolate, testa minutely verruculose, embryo axile, endosperm copious. See Plate 94.
CHROMOSOMES: 2n = c. 78.
DISTRIBUTION: 1 sp.; Australia (Northern Territory, Melville
Island).
ECOLOGY: tropical open forest; geophytes, forest floor, in
laterite on ridges and in sandy soil.
ETYMOLOGY: named after biblical Lazarus, in poetic reference to the morbid colour of the partly buried inflorescence,
which emerges from a leafless subterranean tuber.
95. Lazarum
AREAE : LAZARUM
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A
B
C
D
Plate 95. Lazarum. A, habit × 2; B, inflorescence, nearside half and upper part of spathe removed × 6; C, habit, fruiting × 2; D, berry × 8.
Lazarum mirabile: A–B, Jones 1695 (DNA spirit collection); C–D, Gallen 3 (DNA spirit collection).
C
96. Biarum
Biarum Schott in Schott & Endlicher, Melet. Bot. 17 (1832),
nom. cons. TYPE: B. tenuifolium (L.) Schott (Arum tenuifolium L.), typ. cons.
SYNONYMS: Homaïd Adanson, Fam. 2: 470 (1763), nom.
rej.; [Homaida Rafinesque, Fl. Tell. 3: 63 (1837, “1836”), orth.
var.]; Ischarum (Blume) Reichenbach, Deutsches Bot.
Herbarienbuch, Nom. 32 (1841); Leptopetion Schott, Gen.
Aroid. t. 8 (1858); Cyllenium Schott, Gen. Aroid. t. 9 (1858);
Stenurus Salisb., Gen. Pl. 5 (1866).
HABIT: seasonally dormant herbs, tuber subglobose, smooth.
LEAVES: few to many. PETIOLE: often only weakly differentiated from blade, sheath long to short. BLADE: linear,
266
THE GENERA OF ARACEAE
oblong-lanceolate, oblong-ovate or -obovate, or ellipticoblong, margins smooth to strongly crispate; primary lateral
veins pinnate, ± forming submarginal collective vein, higher
order venation reticulate. INFLORESCENCE: 1(–2) in each floral sympodium, usually appearing before leaves, rarely with
or directly after the leaves at the end of the vegetative period.
PEDUNCLE: short, usually hypogeal. SPATHE: constricted
between tube and blade, erect, eventually evanescent, tube
cylindric to ventricose, hypogeal or held just above ground
surface, margins connate near base or for most of length,
rarely margins free (B. aleppicum), blade usually much longer,
rarely shorter and reduced, expanded to gaping, linear to
oblong-lanceolate or oblong, rarely campanulate or fornicate
or subtriangular, usually dark brown-purple within, rarely
white, pale yellowish or red-purple. SPADIX: sessile, shorter
26f -27 Tribes & Genera Acro 18/7/97 7:26 Page 267
C
A
D
B
E
P
H
Q
F
N
R
S
K
G
J
M
L
Plate 96. Biarum. A, leaf × 2/3; B, detail of fertile portion of spadix and appendix base × 2; C, stamen × 10; D, gynoecium × 10; E, gynoecium, longitudinal section × 10; F, berry, longitudinal section × 2; G, habit × 2/3; H, habit × 2/3; J, detail of fertile portion of spadix and appendix
base × 2; K, habit × 2/3; L, inflorescence × 1; M, inflorescence × 1; N, detail of fertile portion of spadix and appendix base × 2; P, stamen,
side view × 10; Q, stamen, view from below × 10; R, gynoecium × 10; S, gynoecium, longitudinal section × 10. Biarum pyrami var. pyrami:
A, Davis 3844 (K); B–F, Mathew 11056 (Kew spirit collection 55694); B. tenuifolium subsp. tenuifolium: G, du Pavillon 189 (K); H, Davis
1138 (K); J, Archibald & Archibald 5904, Cult. Kew 1985–05490 (Kew spirit collection 49785); B. straussii: K, Hewer 1951 (K); B. davisii subsp.
marmarisense: L, Baytop s.n. (Kew spirit collection 55936); B. ditschianum: M, Bonn accessions 22592 (Kew spirit collection 55925 & 59042);
B. spruneri: N–S, Cult. Mathew (Kew spirit collection 51563).
AREAE : BIARUM
267
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96. Biarum
to much longer than spathe, female zone free, short, hemispheric to subhemispheric, subglobose, separated from male
zone by rather long axis bearing sterile flowers at base or
throughout or rarely naked, male zone 2–3 times longer than
female, rarely with a short zone of sterile flowers above, appendix smooth, either ± slender, elongate-vermiform and not or
hardly stipitate or thicker, cylindric to conoid and stipitate,
rarely procurved and filiform, rarely with a short, basal zone of
filiform processes. FLOWERS: unisexual, perigone absent. MALE
FLOWER: 1–2-androus, stamens free, anthers sessile, connective slender, apiculate and slightly prominent or not, thecae
ellipsoid, with posterior microsporangia ± overtopping anterior
ones, dehiscing by pore or lateral slit extending to the middle
or nearly to the base and confluent apically. POLLEN: presented free or extruded in strands, grains inaperturate, spherical
to subspheroidal, medium-sized (mean 30 µm., range 26–56
µm.), exine spinose or smooth. STERILE FLOWERS: consisting
of either a single filiform, acute or subulate-conic projection, or
rarely composed of 2–3 uncinate, recurved projections from a
single receptacle. FEMALE FLOWER: ovary ovoid or oblongovoid, 1-locular, ovule 1, orthotropous, funicle very short,
placenta basal, stylar region very shortly conic to elongated,
stigma subhemispheric. BERRY: obovoid, white to dull purple,
pericarp carnose, not juicy, infructescence globose to hemispheric, borne at or slightly below soil level. SEED: obovoid
to subglobose, with obconic strophiole, testa smooth to irregularly rugose, thickish, embryo axile, more than half as long
as endosperm, endosperm copious. See Plates 96, 128C.
CHROMOSOMES: 2n = 16, 20, 22, 24, 26, 32, 36, 74, 96, 98.
DISTRIBUTION: 22 spp.; Mediterranean Europe, Middle East,
North Africa:– Albania, Algeria, Croatia, Egypt, Greece (incl.
Crete and islands), Iran, Iraq, Israel, Italy (incl. Sardinia,
Sicily), Jordan, Lebanon, Libya, Macedonia, Morocco,
Portugal, Spain, Syria, Tunisia, Turkey.
ECOLOGY: temperate and warm temperate scrub, woodland, open ground in fields, vineyards, pastures; geophytes,
stony ground, under trees and shrubs, sandy areas, on limestone, rock crevices.
NOTES: Boyce (in press 1) recognized 3 subgenera:– subgen. Biarum; subgen. Cyllenium; subgen. Ischarum (with
3 sections).
ETYMOLOGY: Greek biaron, a name mentioned by Dodoens
(1574).
TAXONOMIC ACCOUNTS: Engler (1920a), Bogner & Boyce
(1989), Boyce & Athanasiou (1991), Boyce (in prep.).
268
THE GENERA OF ARACEAE
Tribe Arisaemateae
Tribe Arisaemateae Nakai, Ord. Fam. Trib. Nov. 221 (1943,
“Arisaematieae”).
Laticifers simple, articulated; tuber depressed-globose, rarely
rhizomatous; leaf blade usually compound, trisect, pedatisect or radiatisect, rarely cordate or trifid, primary lateral
veins of lobes or divisions pinnate, higher order venation
reticulate; spathe tube usually cylindric, blade usually fornicate; spadix with terminal appendix, appendix often
cylindric, clavate or elongate-tapering; flowers unisexual,
perigone absent; ovary 1-locular, ovules orthotropous, placenta basal, style ± attenuate, stigma small; seed testa rough,
endosperm copious.
97. Pinellia
Pinellia Tenore in Atti Accad. Sci. Napoli 4: 69 (1839), nom.
cons. TYPE: P. tuberifera Tenore, nom. illeg. (Arum subulatum Desfontaines, Cat. Pl. Horti Paris p. 385. 1829).
SYNONYMS: Atherurus Blume, Rumphia 1: 135 (1837,
“1835”); Hemicarpurus Nees, Delect. Sem. Horto Bot. Vratisl.
1839: [3] (1839) & in Linnaea 14 Litt.-Ber. 167 (1840).
HABIT: seasonally dormant herbs, tuber subglobose. LEAVES:
few. PETIOLE: sometimes bearing tubercles near base and at
apex, sheath fairly long. BLADE: usually deeply trifid or trisect or pedatisect, or simply cordate, ovate or oblong; primary
lateral veins of each lobe or division pinnate, forming submarginal collective vein, 1–2 distinct marginal veins also
present, higher order venation reticulate. INFLORESCENCE:
solitary, appearing with leaves. PEDUNCLE: shorter or longer
than petiole. SPATHE: slightly constricted between tube and
blade, tube convolute, narrowly ellipsoid to ovate, persistent,
almost closed within by a transverse septum, gaping at base
(P. tripartita), blade oblong-elliptic, boat-shaped, gaping, fornicate, green to purple. SPADIX: much longer than spathe,
female zone adnate to spathe, separated from male zone by
spathe septum and by short, free, naked part of spadix axis,
male zone cylindric, short, terminal sterile appendix smooth,
elongate-subulate, often sigmoid, long-exserted from spathe.
FLOWERS: unisexual, perigone absent. MALE FLOWER: 1androus, stamens sometimes united congenitally in pairs or
groups of four, short, compressed laterally, anthers sessile,
C
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F
H
G
B
C
D
L
E
A
K
M
N
J
Plate 97. Pinellia. A, habit × 2/3; B, stamen × 20; C, gynoecium × 20; D, gynoecium, longitudinal section × 20; E, petiole bulbil × 4; F, infructescence × 2/3; G, leaf × 2/3; H, infructescence × 2/3; J, habit × 2/3; K, inflorescence, nearside half of spathe removed × 3; L, stamen × 20; M,
gynoecium × 20; N, gynoecium, longitudinal section × 20. Pinellia ternata: A–D, Kirkham, Flanagan & Boyce 146, (Kew spirit collection 57610);
Wilson 4100 (K); E, Hickin s.n. (K); P. tripartita: F, Oldham 821 (K); P. pedatisecta: G, Wang x–333 (K); H, Cult. Kew 1962–24001 (Kew spirit
collection 37614); P. cordata: J, Faber 82 (K); K–N, Cult. Boyce (Kew spirit collection 51852 & 58114).
ARISAEMATEAE : PINELLIA
269
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97. Pinellia
connective slender, thecae ellipsoid, dehiscing by apical slit.
POLLEN: extruded in amorphous mass, inaperturate, spherical or subspheroidal, small to medium-sized (mean 25 µm.,
range 21–29 µm.), exine spinulose. FEMALE FLOWER: ovary
ovoid to ovoid-oblong, 1-locular, ovule 1, orthotropous, funicle very short, placenta basal, stylar region attenuate, stigma
small, hemispheric. BERRY: oblong-ovoid, green. SEED:
obnapiform to ellipsoid, testa irregularly verrucose-rugulose
or smooth, embryo axile, elongate or very small and subglobose, endosperm copious. See Plates 97, 128D.
CHROMOSOMES: 2n = 26, 52.
DISTRIBUTION: 6 spp.; temperate east Asia:– China (incl.
Taiwan), Japan (incl. Ryukyu Is.), Korea N. and S.; P. ternata
is occasionally naturalized in Europe and North America.
ECOLOGY: temperate woodland and forest; geophytes, on
ground or on rocks, also on grassy banks and in fields as a
weed (P. ternata).
NOTES: Ulharz (1985) reports that P. tripartita is self-pollinating, probably anemophilous.
ETYMOLOGY: named after Giovanni V. Pinelli (1535–1601).
TAXONOMIC ACCOUNTS: Engler (1920a), Benzing (1969), Li
(1979), Ulharz (1985, 1986), Boyce (1988), Rugh (1990).
C
98. Arisaema
Arisaema Martius in Flora 14: 459 (1831). TYPE: A. speciosum (Wallich) Martius ex Schott (Arum speciosum Wallich),
lectotype selected by Pfeiffer, Nom. Bot. 1: 265. (1873).
SYNONYMS: Dochafa Schott, Syn. Aroid. 24 (1856);
Muricauda J.K. Small, Fl. Southeast U.S. 227 (1903);
Flagellarisaema Nakai in J. Jap. Bot. 25: 5 (1950); Pleuriarum
Nakai in J. Jap. Bot. 25: 5 (1950); Heteroarisaema Nakai in
J. Jap. Bot. 25: 6 (1950); Ringentiarum Nakai in J. Jap. Bot.
25: 6 (1950).
HABIT: seasonally dormant or evergreen herbs, small to
fairly large, stem usually a depressed-globose tuber, producing tubercles or stolons, more rarely a branching,
270
THE GENERA OF ARACEAE
horizontal rhizome. LEAVES: 1–2, rarely 3, cataphylls often
attractively mottled and spotted. PETIOLE: sheaths usually
rather long and imbricate to form a long, usually mottled
pseudostem, margins either free or fused from base to apex
and then with a fringed, ligulate mouth. BLADE: usually
compound, trisect, radiatisect, pedatisect, very rarely simple
and ovate, lobes 3–19 or sometimes more, usually lanceolate-elliptic, varying from linear to broadly ovate, elliptic or
obovate, sometimes rhomboid, sessile or central leaflet often
stalked, margin entire, serrate, erose or coarsely dentate;
primary lateral veins of each lobe or division pinnate, forming submarginal collective vein, 1–2 conspicuous outer
marginal veins also present, higher order venation reticulate.
INFLORESCENCE: solitary, usually appearing with the leaves,
sometimes before them, often subtended by conspicuous
cataphylls, many species producing male and female inflorescences successively from the same plant at different
seasons (paradioecy). PEDUNCLE: very short to longer than
petiole, rarely tuberculate in upper portion (A. scortechinii),
sometimes decurved in fruit. SPATHE: marcescent, usually
unconstricted, rarely slightly constricted (e.g. A. flavum),
lower part erect, convolute into cylindric, often longitudinally striped tube, tube mouth often with revolute to broadly
or even grotesquely auriculate margins, blade usually
strongly fornicate, sometimes erect, widely expanded to
galeate, apex acute to long-acuminate, sometimes drawn
into very long filiform, erect or drooping thread. SPADIX:
usually sessile, sometimes shortly stipitate, free, unisexual or
monoecious, female or monoecious spadices more robust
and differing from male in appendix shape and presence of
sterile organs, female zone densely flowered, usually conoid,
male zone usually laxly flowered and contiguous with
female in monoecious inflorescences, sterile terminal appendix erect, procurved or pendent, entirely hidden within
spathe to very long-exserted, usually somewhat longer than
spathe tube, stipitate or not, cylindric, clavate, rounded,
rugose or apically echinate or drawn out into a sometimes
very long thread, rarely lacking altogether (A. exappendiculatum), often with a few subulate to filiform projections in
basal part, more rarely entirely composed of long filiform
projections. FLOWERS: unisexual, perigone absent. MALE
FLOWER: 2–5-androus, filaments connate forming synandria, synandria ± distant from one another, sessile to
long-stipitate, connective slender, usually inconspicuous,
thecae shortly ovoid, dehiscing by short to long slit or pore,
sometimes confluent into ± lunate or even circular compound thecae dehiscing by a single slit. POLLEN: very dry
and powdery, inaperturate, spherical or subspheroidal, small
(mean 22 µm., range 17–39 µm.), spinose. FEMALE FLOWER:
ovary 1-locular, ovoid or oblong-ovoid, ovules 3–10,
orthotropous, erect, funicle short, placenta basal, stylar region
short to attenuate, always narrower than ovary, stigma usually rather small, subhemispheric. BERRY: obovoid to
obconic, rounded apically, rarely conical, usually few-seeded,
bright red, rarely yellow, glossy. SEED: ovoid to globose,
bearing a strophiole, testa hard, rough, light brown, embryo
axile, endosperm copious. See Plates 98i–iv, 129A.
CHROMOSOMES: 2n = 20, 24, 26, 28, 39, 42, 48, 52, 56, 70,
72, 112, 140, 168 (64).
DISTRIBUTION: ca. 170 spp.; temperate and warm temperate eastern and southeastern North America, northern
Mexico, tropical east and northeast Africa, Arabian Peninsula,
temperate east Asia, tropical south, southeast and east Asia,
Malay Archipelago:– Afghanistan, Bhutan, Brunei, Burma,
26f -27 Tribes & Genera Acro 18/7/97 7:27 Page 271
B
A
C
E
D
Plate 98 (i). Arisaema. A, leaf × 1/2; B, leaf × 1/2; C, leaf × 1/2; D, leaf × 1/2; E, leaf × 1/2. Arisaema candidissimum: A, Cult. Kew 1986–3895
(Kew slide collection); A. grapsospadix: B, Cult. Kew 1987–2421 (Kew slide collection), Murata s.n. (Kew slide collection); A. consanguineum:
C, Cult. Kew 1985–854 (Kew slide collection); A. heterophyllum: D, Cult. Kew 1987–2226 (Kew slide collection); A. abei: E, Cult. Kew
1987–3585 (Kew slide collection).
ARISAEMATEAE : ARISAEMA
271
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C
A
B
E
D
Plate 98 (ii). Arisaema. A, habit × 1/4; B, detail of inflorescence emergence from pseudostem ape× × 2/3; C, habit × 1/4; D, habit × 1/4;
E, habit in flower × 1/4. Arisaema abei: A–B, Cult. Kew 1987–3585 (Kew slide collection); A. grapsospadix: C, Cult. Kew 1987–2421 (Kew
slide collection); Murata s.n. (Kew slide collection); A. kiushianum: D, Murata s.n. (Kew slide collection); A. candidissimum: E, Cult. Kew
1986–3895 (Kew slide collection).
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THE GENERA OF ARACEAE
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E
F
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A
B
J
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M
P
R
S
Plate 98 (iii). Arisaema. A, male inflorescence × 2/4; B, male spadix × 2; C, synandrium × 10; D, female spadix × 2; E, gynoecium × 10; F,
gynoecium, longitudinal section × 10; G, male inflorescence × 2/3; H, male spadix, most of appendi× removed × 2; J, synandrium × 10; K,
male inflorescence × 2/3; L, male spadix × 2; M, synandrium × 10; N, female inflorescence × 2/3; P, female spadix × 2; Q, gynoecium × 10;
R, gynoecium, longitudinal section × 10; S, female inflorescence × 2/3. Arisaema nikoense var. nikoense: A–F, Cult. Kew 1987–2861 (Kew
spirit collection 55951 & Kew slide collection); A. griffithii: G–J, Cult. Kew 1988–466 (Kew spirit collection 55695 & Kew slide collection);
A. taiwanense: K–M, Cult. Kew 1987–3583 (Kew spirit collection 49912 & Kew slide collection); A. ringens: N–R, Cult. Kew 1987–3583 (Kew
spirit collection 49912 & Kew slide collection); A. tortuosum: S, Cult. Kew 1984–4797 (Kew slide collection).
ARISAEMATEAE : ARISAEMA
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A
D
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M
B
E
F
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L
Plate 98 (iv). Arisaema. A, male inflorescence × 2/3; B, male spadix × 1; C, stamen × 10; D, female spadix × 2; E, gynoecium × 10; F, gynoecium, longitudinal section × 10; G, monoecious inflorescence × 2/3; H, monoecious spadix × 2; J, stamen × 10; K, gynoecium × 10; L,
gynoecium, longitudinal section × 10; M, female inflorescence × 2/3. Arisaema exappendiculatum: A–F, Bown 184/26 (Kew slide collection);
B–F, Cult. Kew 1969–9202 (Kew spirit collection 49914); A. flavum subsp. flavum: G–L, Cult. Kew 1968–65 (Kew spirit collection 54924 &
Kew slide collection); A. fimbriatum: M, Rubeli s.n. (Kew slide collection).
98. Arisaema
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THE GENERA OF ARACEAE
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Burundi, Cambodia, Canada, China (incl. Taiwan), Ethiopia,
India, Indonesia (Borneo, Flores, Java, Sulawesi, Sumatra,
Timor), Japan, Kenya, N. and S. Korea, Laos, Malaysia
(Borneo, Peninsula), Mexico, Nepal, Oman, Pakistan,
Philippines, Russia (Far East), Rwanda, Saudi Arabia, Somalia,
Sri Lanka, Sudan, Tanzania, Thailand, Uganda, USA, Vietnam,
Yemen Republic, Zaïre.
ECOLOGY: temperate, subtropical and upland tropical forest, more rarely savanna, lowland tropical forest (Sarawak),
subdesert or montane grassland (up to 4500m alt.); geophytes, forest floor, rocky slopes, rarely in wet places, very
rarely epiphytic.
NOTES: Murata (1990a) recognized 11 sections:– Fimbriata,
Decipientia, Trisecta, Franchetiana, Pedatisecta, Clavata,
Tortuosa, Dochafa, Tenuipistillata, Sinarisaema and Arisaema.
ETYMOLOGY: Greek aris, aridos (name of a small herb
mentioned by Pliny) and haima, haimatos (blood).
TAXONOMIC ACCOUNTS: Engler (1920a), Hara (1971), Li
(1979, 1980), Ohashi & Murata (1980), Sivadasan (1982),
Murata (1984, 1987, 1990a), Mayo & Gilbert (1986), Pradhan
(1990).
C
Tribe Colocasieae
Tribe Colocasieae Engler in Nova Acta Acad. Leopold.Carol. 39: 149 (1876).
Laticifers anastomosing (except Ariopsis); primary lateral
veins of leaf blade or leaflets (Protarum) pinnate, forming
submarginal collective vein, at least 1–2 other marginal veins
also present, higher order venation intermediate between
parallel-pinnate and reticulate; spathe usually constricted
centrally (except Ariopsis) with lower, convolute, persistent
tube and upper, gaping, ± boat-shaped, marcescent to
caducous blade; flowers unisexual, perigone absent; male
flower a synandrium of several connate stamens, common
connectives thick, fleshy, thecae lateral, pollen inaperturate;
endosperm copious.
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99. Ariopsis
Ariopsis Nimmo in J. Graham, Cat. Pl. Bombay 252 (1839).
TYPE: A. peltata Nimmo
Laticifers simple, articulated. HABIT: small, seasonally dormant herbs, tuber ± subglobose, hypogeal. LEAVES: usually
solitary, rarely few. PETIOLE: slender, sheath fairly short.
BLADE: peltate, cordate-ovate or only emarginate basally,
thin, glaucous below, posterior lobes very short; primary lateral veins pinnate and also radiating from petiole insertion,
forming submarginal collective vein, marginal vein also present, higher order venation reticulate. INFLORESCENCE: 1–3
in each floral sympodium, appearing with or without leaves.
PEDUNCLE: very slender, much longer than spathe, erect.
SPATHE: ovate, boat-shaped, fornicate, not constricted, gaping widely, not convolute at base, marcescent. SPADIX:
shorter than spathe, female zone adnate to spathe, very short
and few-flowered, sometimes separated from male zone by
short, free, naked axis, male zone fertile to apex, relatively
thick, cylindric-conoid, many-flowered. FLOWERS: unisexual,
perigone absent. MALE FLOWER: synandrium peltate, connate filaments forming a stipe longer and narrower than
dilated common connective, thecae subglobose to ellipsoid,
99. Ariopsis
dehiscing by oval pore, synandria all connate apically, forming continuous surface punctured by cavities with somewhat
prominent margins into which pollen is shed from the 6(–8)
surrounding thecae (each pair of thecae belonging to a different synandrium). POLLEN: inaperturate, spherical or
subspheroidal, small (mean 20 µm.), exine spinose. FEMALE
FLOWER: ovary ovoid to ovoid-oblong, 1-locular, ovules many,
orthotropous, placentae 4–6, parietal, extending from base to
apex of locule, stylar region absent, stigma stellate with 4–6laciniate lobes, lobes initially erect, later spreading and
reflexed. BERRY: 4–6-angled, stigma persistent, many-seeded.
SEED: oblong, apically narrowed and obtuse, with indistinct
strophiole, testa thickish, longitudinally costate, embryo axile,
small, endosperm copious. See Plates 99, 129B.
CHROMOSOMES: 2n = 28, 84.
DISTRIBUTION: 2 spp.; tropical south Asia:– Bhutan, Burma,
India (Assam, Sikkim, Western Ghats), Nepal.
ECOLOGY: tropical evergreen forest; geophytes on forest
floor or in rock crevices.
NOTES: The correct morphological interpretation of the male
flowers remains unclear.
ETYMOLOGY: Greek aron (Arum) and -opsis (appearance).
TAXONOMIC ACCOUNTS: Engler (1920a), Nicolson (1976),
Sivadasan (1982), Bogner & Boyce (in prep.).
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100. Protarum
Protarum Engler in Bot. Jahrb. 30, Beibl. 67: 42 (1901).
TYPE: P. sechellarum Engler
HABIT: seasonally (?irregularly) dormant herb, tuber subglobose, with numerous, very densely arranged, annular leaf
scars. LEAF: solitary. PETIOLE: long, sheath short. BLADE:
pedatisect to radiatisect, almost radiate, leaflets shortly stalked,
elliptic to narrowly elliptic, acuminate; primary lateral veins of
lobes pinnate, numerous, forming submarginal collective vein,
2 marginal veins also present, higher order venation reticulate.
INFLORESCENCE: solitary, appearing with or without leaves.
PEDUNCLE: short, much shorter than petiole. SPATHE: slightly
constricted between tube and blade, tube convolute, shorter
than blade, blade erect, boat-shaped, marcescent. SPADIX:
sessile, much shorter than spathe, female zone conoid, sep-
C O L O C A S I E A E : P R OTA R U M
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K
F
D
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H
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A
B
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Plate 99. Ariopsis. A, habit × 1; B, spadix × 6; C, gynoecium × 15; D, gynoecium, longitudinal section × 15; E, section through male portion of spadix to show synandrium arrangement × 10; F, infructescence × 6; G, habit in flower, showing branching of tubers × 1; H, leaf ×
1; J, spadix × 6; K, berry × 6; L, seed × 12. Ariopsis peltata: A, Talbot 496 (K); B–E, Bogner 1922 (Kew spirit collection 56425); F, Barnes
1087 (K); A. protanthera: G–H, Cult. Kew.1851 (K); J, Kurz s.n. (K); K–L, Cult. Kew. 1851 (Kew spirit collection 58040).
276
THE GENERA OF ARACEAE
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K
A
J
B
H
G
C
E
F
D
Plate 100. Protarum. A, leaf × 1/6; B, leaflet × 1/3; C, tuber × 1/2; D, inflorescence × 2/3; E, spadix × 2; F, detail of gynoecia, top view ×
8; G, synandrium, top view × 15; H, gynoecium with associated staminode, longitudinal section × 15; J, infructescence, nearside half of spathe
removed × 2/3; K, seed × 4. Protarum sechellarum: A, 5495 (Kew slide collection); B, Milne 14 (K); C, Jeffrey 485 (Kew spirit collection 25047);
D, Thomasset s.n. (K); E–H, Whitehead 35 (Kew spirit collection 37323); J–K, Gardiner 110 (K & Kew spirit collection 58062).
C O L O C A S I E A E : P R OTA R U M
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100. Protarum
101. Steudnera
arated from male zone by more slender sterile zone covered
with narrowly elongated synandrodes or partly naked, male
zone ± cylindric to obconic, terminal sterile appendix thicker,
digitiform, obtuse, ± smooth. FLOWERS: unisexual, perigone
absent. MALE FLOWER: synandrium 3–6-androus, sessile,
subprismatic, ± excavated centrally, fused connectives broad,
margins lobed, thecae broadly ellipsoid to subglobose,
dehiscing by broad apical slit. POLLEN: inaperturate, ellipsoid, small (21 µm., range 20–22 µm.), exine striate. FEMALE
FLOWER: gynoecium surrounded by whorl of 4–6, free, ±
imbricate, thickish, oblong, subprismatic staminodes, ovary
ovoid to ellipsoid, 1-locular, ovules 4, hemiorthotropous,
micropyle elongate, funicle short, placenta basal, stylar region
shortly attenuate or nearly absent, stigma 2–4-lobed, much
broader than style. BERRY: ± ellipsoid to obovoid, with persistent stigma remnant, usually 1-seeded, orange,
infructescence enclosed by persistent and much enlarged
spathe tube. SEED: ovoid to ellipsoid-oblong, testa costate,
dark brown, embryo small, flattened and disc-like,
endosperm copious. See Plate 100.
CHROMOSOMES: 2n = 28.
DISTRIBUTION: 1 sp.; Seychelles Islands (Mahé, Praslin,
Silhouette).
ECOLOGY: tropical (palm) forest, moss forest; geophytes, forest floor, leaf litter in rock crevices, often on large granitic
rocks.
ETYMOLOGY: Greek protos (first) and Arum.
TAXONOMIC ACCOUNTS: Engler (1920a), Bogner (1973b),
Robertson (1989).
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101. Steudnera
Steudnera K. Koch in Wochenschr. Gärtnerei Pflanzenk. 5:
114 (1862). TYPE: S. colocasiifolia K. Koch (“colocasiaefolia”).
HABIT: medium sized to robust herbs, usually evergreen,
sometimes seasonally dormant, stem epigeal, stout, erect or
creeping, covered with fibrous remains of leaves and cata-
278
THE GENERA OF ARACEAE
phylls. LEAVES: solitary or few to several. PETIOLE: sheath
very short. BLADE: peltate, ovate or ovate-oblong, acuminate, often emarginate at base; basal ribs short,
well-developed, primary lateral veins pinnate, forming submarginal collective vein very near margin, marginal vein
also present, secondary and tertiary laterals arising from the
primaries at a wide angle, then arching towards leaf margin
and forming ± conspicuous interprimary collecting vein,
higher order venation reticulate. INFLORESCENCE: solitary.
PEDUNCLE: shorter than petiole. SPATHE: yellow or ± dark
purple within, ovate or ovate-lanceolate, acuminate, not
constricted, barely convolute at base, ± fully expanded at
anthesis, lower part persistent to fruiting stage, upper part
becoming reflexed and revolute, marcescent. SPADIX: much
shorter than spathe, densely flowered, female zone cylindric,
often longer than male, mostly adnate to spathe, male zone
contiguous with female, cylindric, ellipsoid or subglobose,
fertile to apex, obtuse. FLOWERS: unisexual, perigone
absent. MALE FLOWER: 3–6-androus, stamens connate,
synandrium strongly lobed, apically truncate, common connective relatively small, impressed at apex, thecae oblong,
contiguous, dehiscing by apical pore. POLLEN: inaperturate, ellipsoid-oblong, small (mean 22 µm.), exine striate.
FEMALE FLOWER: gynoecium surrounded by whorl of 2–5,
short, claviform staminodes, more rarely staminodes absent,
ovary subglobose to ovoid, 1-locular, ovules numerous,
hemiorthotropous, funicle distinct, placentae 2–5, parietal, in
basal part only or extending from base to apex, stylar region
± lacking, stigma strongly 2–5-lobed. BERRY: ovoid, manyseeded. SEED: ovoid to ellipsoid, testa costate, embryo axile,
short, conoid, endosperm copious. See Plates 101, 129C.
CHROMOSOMES: 2n = 28, 56.
DISTRIBUTION: 8 spp.; tropical south and southeast Asia:–
Bangladesh, Burma, ?Cambodia, China (Guangxi, Yunnan),
India (Assam), Laos, Thailand, Vietnam.
ECOLOGY: tropical humid forest; geophytes on forest floor.
ETYMOLOGY: named after H. Steudner (1832–1863).
TAXONOMIC ACCOUNTS: Krause in Engler & Krause (1920),
Boyce (1995c).
26f -27 Tribes & Genera Acro 18/7/97 7:30 Page 279
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D
E
H
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G
B
F
A
Plate 101. Steudnera. A, habit × 2/3; B, spadix × 2; C, synandrium, top view × 15; D, synandrium, side view × 15; E, gynoecium, top view
× 15; F, gynoecium, longitudinal section × 15; G, inflorescence, nearside half of spathe removed × 2/3; H, synandrium, side view × 15; J,
gynoecium with associated staminode × 15. Steudnera henryana: A, Henry 11986 (K); B–F, S. discolor: Bogner 1814 (Kew spirit collection
57576); S. colocasioides: G–J, Cult. Kew (K & Kew spirit collection 58060).
COLOCASIEAE : STEUDNERA
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102. Remusatia
Remusatia Schott in Schott & Endlicher, Melet. Bot. 18
(1832). TYPE: R. vivipara (Roxburgh) Schott (Arum viviparum Roxburgh, “viviparium”).
SYNONYM: Gonatanthus Klotzsch in Link, Klotzsch &
Otto, Icon. Pl. Rar. Hort. Berol. 1: 33 (1841). TYPE: G. sarmentosus Klotzsch
HABIT: small to medium-sized, seasonally dormant herbs,
tuber subglobose, producing erect to spreading,
unbranched or branching stolons from axils of scarious,
deciduous cataphylls, stolons producing small, ovoid tubercles at nodes, each invested by numerous, apically revolute
or flexuose scales (minute cataphylls). LEAVES: 1–2. PETIOLE: sometimes slender, sheath relatively short. BLADE:
peltate, cordate-lanceolate to cordate-ovate, acuminate;
basal ribs well-developed, primary lateral veins pinnate,
forming submarginal collective vein very close to margin,
marginal vein also present, secondary and tertiary laterals
arising from the primaries at a wide angle, then arching
towards leaf margin and forming inconspicuous interprimary collective veins, higher order venation reticulate.
INFLORESCENCE: solitary, appearing with or without leaf.
PEDUNCLE: shorter than petiole. SPATHE: strongly constricted between tube and blade, sometimes with secondary
constriction above the spadix, tube with convolute margins,
persistent, enclosing female zone and sterile zone of spadix,
blade yellow or red, longer than tube, fully expanded or
remaining convolute and opening only at base, sometimes
becoming reflexed (R. vivipara, R. yunnanensis), later deciduous. SPADIX: sessile or subsessile, much shorter than
spathe, female zone subcylindric, about half as long as
spathe tube, separated from male zone by much narrower
zone of sterile male flowers, male zone ellipsoid or subclavate, fertile to apex, obtuse. FLOWERS: unisexual,
perigone absent. MALE FLOWER: 2–3-androus, stamens connate into cuneate-clavate, 4–6-sulcate synandrium, fused
filaments distinct, common connectives somewhat excavated
at apex, thecae 4–6, oblong to ellipsoid, dehiscing by api-
102. Remusatia
280
THE GENERA OF ARACEAE
cal pore-like slit. POLLEN: extruded in strands, inaperturate,
spherical to subspheroidal, medium-sized (mean 32–33 µm.),
spinose. STERILE MALE FLOWERS: each a ± elongated synandrode. FEMALE FLOWER: staminodes absent, ovary
subcylindric to subglobose, 1-locular or partially 2–4-locular
at apex, ovules many, hemiorthotropous, funicle short to
long, placentae 2–4 and parietal or placenta 1 and basal, stylar region very shortly attenuate or lacking, stigma
discoid-subcapitate or slightly 3–4-lobed. BERRY: obovoid
to globose, many-seeded, infructescence ellipsoid, borne
within persistent spathe tube. SEED: ellipsoid to subglobose,
covered by thick, succulent sarcotesta or testa verruculose to
irregularly costate, embryo axile, short, ovoid to subglobose,
endosperm copious. See Plates 102, 129D.
CHROMOSOMES: 2n = 28, 42, 56.
DISTRIBUTION: 4 spp.; tropical Africa, tropical Asia, Malay
Archipelago, Australasia: Australia (N.), Bangladesh, Bhutan,
Cameroon, China (Taiwan, Yunnan, Tibet), Christmas Is.,
Ethiopia, Guinea, India, Indonesia (Java), Ivory Coast, Liberia,
Madagascar, Nepal, Nigeria, Oman, ?Saudi Arabia, Sierra
Leone, Sri Lanka, Tanzania, Thailand, Vietnam, Yemen
Republic (Socotra), Zaïre, Zambia.
ECOLOGY: tropical seasonal forest; epiphytes, lithophytes or
geophytes, moss-laden boughs, rock crevices, damp banks,
forest floor.
NOTES: Li & Hay (1992a, b) recognize 2 sections, sect.
Remusatia and sect. Gonatanthus.
ETYMOLOGY: named after A. Rémusat (1788–1832).
TAXONOMIC ACCOUNTS: Krause in Engler & Krause (1920),
Sivadasan (1982), Mayo (1985a), Li (1987a, b, 1991, 1992), Li
& Hay (1992a, 1992b).
103. Colocasia
Colocasia Schott in Schott & Endlicher, Melet. Bot. 18 (1832),
nom. cons. TYPE: C. antiquorum Schott (Arum colocasia
L.), typ. cons.
SYNONYM: Leucocasia Schott in Oesterr. bot. Wochenbl.
7: 34 (1857).
C
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E
D
A
B
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J
M
C
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K
F
P
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L
Q
Plate 102. Remusatia. A, habit in flower with stolons × 1/4; B, habit with stolons × 1/4, C, leaf × 2/3; D, tubercle × 6; E, plantlet emerging
from tubercle × 2/3; F, inflorescence × 2/3; G, spadix × 2; H, synandrium, top view × 12; J, synandrium, side view × 12; K, synandrode ×
15; L, gynoecium, longitudinal section × 12; M, gynoecium, transverse section × 12; N, habit × 1/3; P, inflorescence × 2/3; Q, gynoecium,
longitudinal section × 12. Remusatia vivipara: A, 299 (Kew slide collection); B, 300 (Kew slide collection); C–D, Kerr 1438 (K); E, Cult. Kew
1969–5188 (Kew spirit collection 59039); F–M, Bogner 2121 (Kew spirit collection 57570); Cult. Kew 1947–85 (Kew spirit collection 19155);
R. pumila: N, Grey-Wilson & Phillips 128 (K); P, C.K. 227 (K); Q, Grierson & Long 2215 (K).
COLOCASIEAE : REMUSATIA
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B
D
G
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J
E
H
F
A
L
Plate 103. Colocasia. A, habit × 1/2; B, inflorescence × 2/3; C, synandria, top view × 5; D, gynoecium, longitudinal section × 11; E, floral
sympodium with associated petiole sheath × 1/3; F, spadix × 1; G, synandria, top view × 5; H, synandrium, side view × 10; J, gynoecium,
longitudinal section; K, gynoecium, transverse section; L, habit × 1/5. Colocasia fallax: A, Gamble 27041 (K); B–D Chantaranothai et al. 90/464
(Kew spirit collection 59076); C. gigantea: E, Bown 197/26 (Kew slide collection); F–K, Bogner 427 (Kew spirit collection 34491); C. esculenta: L, Townsend s.n. (Kew slide collection).
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THE GENERA OF ARACEAE
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HABIT: small, medium-sized or gigantic, seasonally dormant
or evergreen herbs, stem either a hypogeal, subglobose or
subcylindric tuber or mostly epigeal, massive. LEAVES: several, rosulate in acaulescent plants, forming terminal crown
in arborescent species. PETIOLE: sheath rather long. BLADE:
peltate, ovate-cordate to sagittate-cordate, posterior lobes
rounded, shortly to almost entirely connate; basal ribs welldeveloped, primary lateral veins pinnate, forming
submarginal collective vein, 1–2 marginal veins also present, secondary and tertiary laterals arising from the
primaries at a wide angle, then arching strongly towards
leaf margin and forming inconspicuous interprimary collective veins, higher order venation reticulate.
INFLORESCENCE: 1–many in each floral sympodium,
appearing with the leaves. PEDUNCLE: much shorter than
petiole. SPATHE: constricted between tube and blade, sometimes with a second constriction above male zone of spadix,
tube with convolute margins, usually much shorter than
blade, ovoid or oblong, persistent, enlarging in fruit and
then splitting open irregularly, blade white to yellow, oblong
and boat-shaped to narrowly lanceolate, reflexing at anthesis, later deciduous. SPADIX: sessile, shorter than spathe,
female zone short, separated from male by narrower zone
of sterile male flowers, male zone cylindric to fusiform, terminal appendix erect, ± smooth, elongate-conoid to fusiform
or subulate, sometimes reduced to small, mucronate stub,
rarely absent. FLOWERS: unisexual, perigone absent. MALE
FLOWER: 3–6-androus, stamens connate into ± truncate
synandrium, thecae lateral, oblong-linear, dehiscing by apical pore. POLLEN: extruded in strands, inaperturate,
ellipsoid-oblong or spherical to subspheroidal (C. esculenta),
small to medium-sized (mean 25 µm., range 25–26 µm),
exine finely striate, coarsely swirling-fossulate or fossulatespinose. STERILE MALE FLOWERS: synandrodes
depressed-obpyramidal, truncate, laterally compressed.
FEMALE FLOWER: ovary ovoid or oblong, 1-locular, ovules
many, hemiorthotropous, funicles relatively long, placentae
2–5, parietal, stylar region short, narrowed or not, sometimes
± absent, stigma discoid-capitate or weakly lobed. BERRY:
greenish to whitish or red(?), obconoid or oblong, stigma
remnants persistent, many-seeded. SEED: ovoid to ellipsoid,
103. Colocasia
testa thickish, costate, embryo axile, cylindric, endosperm
copious. See Plates 103, 130A.
CHROMOSOMES: 2n = 28, 42, 56.
DISTRIBUTION: 8 spp.; tropical Asia, Malay Archipelago:–
Bangladesh, Bhutan, Burma, Cambodia, China (Guandong,
Guangxi, Guizhou, Hainan, Hunan, Sichuan, Taiwan,
Yunnan), India, Indonesia (Java, Lesser Sunda Is.), Laos,
Malaysia (Peninsula), Nepal, Sri Lanka, Thailand, Vietnam.
The country list given here does not include C. esculenta.
This species is cultivated and naturalized throughout the
humid tropics and subtropics. Its natural area of distribution
remains somewhat obscure but is certainly tropical Asian,
extending into the Malay Archipelago and perhaps as far as
Papuasia and Australia.
ECOLOGY: tropical humid forest habitats; geophytes, terrestrial or helophytes, wet places, along streams and ponds,
forest floor in leaf litter, between rocks, sometimes on limestone (C. gigantea).
NOTES: Krause in Engler & Krause (1920) recognized 2 sections:– sect. Colocasia (“Tuberosae”), sect. Caulescentes.
VERNACULAR NAMES AND USES: taro, eddoe; C. esculenta
is an important food plant in tropical regions, especially the
Pacific.
ETYMOLOGY: classical name, Greek kolokasia, from an old
Middle Eastern name qolqas.
TAXONOMIC ACCOUNTS: Krause in Engler & Krause (1920);
Sivadasan (1982), Plucknett (1983), Shaw (1984), Sreekumari
& Mathew (1991a, b), Li & Wei (1993).
C
104. Alocasia
Alocasia (Schott) G. Don in Sweet, Hort. Brit., ed. 3: 631
(1839), nom. cons. TYPE: A. cucullata (Loureiro) G. Don
(Arum cucullatum Loureiro), typ. cons.
SYNONYMS: Colocasia sect. Alocasia Schott in Schott &
Endlicher, Melet. Bot. 18 (1832); Ensolenanthe Schott in
Bonplandia 9: 368 (1861); Xenophya Schott in Ann. Mus.
Bot. Lugduno–Batavum 1: 124 (1863); Schizocasia Schott ex
Engler in Bot. Jahrb. 1: 185 (1880, “1881”); Panzhuyuia Z.Y.
Zhu in J. Sichuan Chinese Medicinal School 4 (5): 49 (1985).
104. Alocasia
COLOCASIEAE : ALOCASIA
283
26f -27 Tribes & Genera Acro 18/7/97 7:32 Page 284
C
A
F
D
E
B
K
J
G
M
H
L
Plate 104 (i). Alocasia. A, leaf × 1/3; B, inflorescence × 1; C, synandrium, side view × 8; D, gynoecium, longitudinal section × 8; E, leaf ×
1/3; F, habit × 1/6; G, infructescence with associated petiole and plant base × 1/8; H, spadix × 2; J, synandrium × 10; K, gynoecium × 10; L,
gynoecium, longitudinal section × 10; M, habit × 2/3. Alocasia brancifolia: A, Cult. Veitch 10 June 1884 (K); B–D, Bogner 1736 (Kew spirit
collection 58916); A. guttata: E, Forman 931 (K); A. lowii: F–G, Boyce 384 (Kew slide collection); H–L, Boyce 384 (Kew spirit collection 49923);
A. beccarii : M, Simpson 2271 (K); Wood 798 (Kew spirit collection 52879).
284
THE GENERA OF ARACEAE
26f -27 Tribes & Genera Acro 18/7/97 7:32 Page 285
D
E
C
F
B
A
Plate 104 (ii). Alocasia. A, habit × 2/3; B, spadix × 2; C, synandrium, side view × 15; D, gynoecium × 15; E, gynoecium, longitudinal section × 15; F, infructescence. Alocasia beccarii: Alston 14176 (BM).
HABIT: medium-sized to rarely arborescent and gigantic,
seasonally dormant to evergreen herbs, stem thick, often
hypogeal, sometimes stoloniferous and bulbiferous, epigeal
stem usually erect, rarely elongated and creeping, with
clear to milky latex. LEAVES: few to several in terminal
crown, sometimes each subtended by a cataphyll. PETIOLE: long, sometimes asperate or glandular, sheath
relatively long, sometimes deciduous. BLADE: sometimes
pubescent, juvenile blade peltate, at maturity usually sagittate, less often ± hastate or cordate, peltate in some species,
margin entire, sinuate or slightly to deeply pinnatifid, posterior divisions ovate or triangular; basal ribs
well-developed, glands present in axils of primary lateral
veins and midrib, primary lateral veins pinnate, forming
submarginal collective vein,1–2 closely adjacent marginal
veins also present, secondary and tertiary lateral veins arising from the primaries at a wide angle, then arching strongly
towards leaf margin, sometimes forming interprimary veins,
higher order venation reticulate. INFLORESCENCE: 2–many
in each floral sympodium, appearing with the leaves.
PEDUNCLE: usually shorter than petiole. SPATHE: strongly
constricted between tube and blade, tube with convolute
margins, shorter than blade, ovoid or oblong, persistent
and then splitting irregularly in fruit, blade oblong, usually
boat-shaped, rarely fornicate, at anthesis at first erect, then
reflexing and later usually deciduous; in Xenophya group
blade is persistent, erect, convolute, gaping only basally.
SPADIX: sessile, sometimes shortly stipitate, rarely obliquely
adnate, shorter than spathe, female zone short, conoidcylindric, separated from male by a much narrower zone of
sterile flowers, male zone usually cylindric, appendix
conoid to cylindric, surface with irregular, labyrinthine network of fissures. FLOWERS: unisexual, perigone absent.
MALE FLOWER: 3–12(–36)-androus, stamens connate into
COLOCASIEAE : ALOCASIA
285
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an obpyramidal, subhexagonal, truncate, rarely linear (A.
brisbanensis) synandrium, thecae oblong to linear-oblong,
lateral, dehiscing by apical pore. POLLEN: extruded in
strands, inaperturate, spherical to subspheroidal, mediumsized (mean 35 µm., range 31–39 µm.), exine spinose.
STERILE MALE FLOWERS: synandrodes shallow, obpyramidal, compressed, truncate. FEMALE FLOWER: ovary ovoid
or oblong, 1-locular or partially 3–4-locular at apex, ovules
6–10, orthotropous, hemiorthotropous, hemianatropous or
anatropous, funicle short, placenta basal, stylar region short,
stigma depressed-capitate, ± distinctly 3–4-lobed. BERRY:
generally reddish, ellipsoid or obconic-ellipsoid or subglobose, 1–5-seeded, stigma remnants persistent. SEED:
subglobose to ellipsoid, testa thickish, smooth or scabrous,
embryo broadly conoid, shortly cylindric or elongate,
endosperm copious. See Plates 104i–ii, 130B.
CHROMOSOMES: 2n = 28, 42, 56, 70, 84.
DISTRIBUTION: 60–70 spp.; tropical Asia, Australasia, Malay
Archipelago, Melanesia:– Australia (Queensland, New South
Wales), Bangladesh, Brunei, Burma, Cambodia, China (incl.
Taiwan), Fiji, India, Indonesia (Borneo, Irian Jaya, Java,
Moluccas, Sulawesi, Sumatra), Japan (incl. Ryukyu Is.), Laos,
Malaysia (Borneo, Peninsula), Nepal, Papua New Guinea,
Philippines, Solomon Is., Sri Lanka, Thailand, Vietnam. A.
macrorrhizos, A. plumbea and A. cucullata are cultivated
and naturalized throughout the tropics.
ECOLOGY: tropical and subtropical humid forest; geophytes
or terrestrial, forest floor, in leaf litter, humus deposits on
rocks, usually in deep shade, sometimes in exposed areas of
forest regrowth.
ETYMOLOGY: Greek a- (not) and Colocasia, the latter without its first syllable, implying a genus close to but different
from Colocasia.
TAXONOMIC ACCOUNTS: Krause & Engler in Engler &
Krause (1920), Nicolson (1968a), Sivadasan (1982), Burnett
(1985), Hay (1990a), Hay & Wise (1991).
C
Tribe Pistieae
Tribe Pistieae Blume, Rumphia 1: 76 (1836, “Pistiaceae”).
Laticifers absent; plant small, acaulescent; leaves several,
rosulate, densely pubescent; petiole very short; blade obovate-cuneate to oblong, apically rounded to retuse, midrib
absent, primary veins subparallel, higher order venation
reticulate; inflorescence 1, very small; spathe ± constricted,
lower margins connate forming tube, free margins between
tube and blade folded to form a partition separating upper
male partial chamber from lower female one, blade gaping;
spadix:– female zone with single basal gynoecium and thin
pouch-shaped flap below spathe partition, male zone with
2–8 flowers in a whorl, subtended by thin annular flap,
spadix apex ± prominulent, naked, very short; flowers unisexual, perigone absent; male flower a sessile synandrium
of 2 connate stamens, thecae dehiscing by single apical slit,
pollen exine plicate with strongly undulate frills running
length of grain; ovary obliquely adnate to spadix axis, 1locular, ovules numerous, orthotropous, placenta parietal
(morphologically basal), style distinct, curved, stigma small;
berry thin-walled, several-seeded, pericarp eventually
decaying; seed subcylindric, testa thick, reticulate-alveolate,
with micropylar operculum formed by both integuments,
embryo minute, endosperm copious.
286
THE GENERA OF ARACEAE
105. Pistia
Pistia L., Sp. Pl. 963 (1753). TYPE: P. stratiotes L.
SYNONYMS: Kodda-Pail Adanson, Fam. 2: 75, 541
(1763); Zala Loureiro, Fl. Cochinch. 401, 405 (1790);
Apiospermum Klotzsch in Abh. Königl. Akad. Wiss. Berlin
1852: 351 (1853); Limnonesis Klotzsch in Abh. Königl. Akad.
Wiss. Berlin 1852: 352 (1853).
Laticifers absent. HABIT: small, free-floating evergreen herb
with pendent feathery roots, stem very short, acaulescent,
stoloniferous. LEAVES: several in a rosette, densely pubescent. PETIOLE: very short, almost absent, sheath very short,
ligulate, very thin, scarious at base. BLADE: somewhat
spongy, obovate-cuneate to obovate-oblong, apically
rounded, truncate or retuse; midrib absent, primary veins
subparallel, all arising from base, diverging slightly and
running into margin near apex, strongly prominent on
lower surface, higher order venation reticulate. INFLORESCENCE: solitary, very small, much shorter than leaves.
PEDUNCLE: very short, pubescent. SPATHE: pubescent
without, glabrous within, somewhat constricted centrally,
lower margins connate with each other and with ovary
wall forming tube, free margins between tube and blade
folded between stigma and male organs forming a partition
between an upper male partial chamber and a lower female
one, blade erect, ovate, expanded, acute-acuminate.
SPADIX: shorter than spathe, mostly adnate to spathe, only
the apical male zone free, female zone bearing single
gynoecium at base and a thin, green, pouch-shaped flap
just below spathe partition, male zone subtended by a thin,
marginally lobed, green, annular flap, composed of a
basally naked spadix axis supporting a single whorl of 2–8
flowers, naked axis sometimes extending a little beyond.
FLOWERS: unisexual, perigone absent. MALE FLOWER:
synandrium composed of 2 connate stamens, thecae dehiscing by single apical slit. POLLEN: inaperturate,
ellipsoid-elongate to -oblong, medium-sized (mean 27
µm.), exine plicate with strongly undulate frills running
the length of the grain. FEMALE FLOWER: gynoecium
obliquely adnate to spadix axis, ovary ovoid, 1-locular,
ovules numerous, orthotropous, placenta broad, apparently parietal, probably morphologically basal, stylar region
attenuate, bending inwards towards male flowers, stigma
small, discoid-subcapitate. BERRY: thin-walled, utricular,
several-seeded, ellipsoid, irregularly breaking up and
decaying to release seeds. SEED: barrel-shaped, ± subtruncate and excavated at apex and base, testa thick,
reticulate-alveolate, thicker and with operculum at micropylar end, embryo obovoid to conoid, endosperm copious.
See Plates 105, 130C.
CHROMOSOMES: 2n = 28.
DISTRIBUTION: 1 sp.; pantropical:– Afghanistan, Angola,
Argentina, Australia, Bangladesh, Belize, ?Benin, Bolivia,
Botswana, Brazil, Brunei, Burkina Faso, Burundi, Cambodia,
Cameroon, Central African Republic, Chad, China (incl.
Taiwan), Colombia, Comores Is., Congo, Costa Rica, Cuba,
Dominican Republic, Ecuador, Egypt, Equatorial Guinea
(Rio Muni), Ethiopia, Gambia, Ghana, Guatemala, Guinea,
Guyana, Haiti, Honduras, India, Indonesia (Borneo, Irian
Jaya, Java, Moluccas), Ivory Coast, Jamaica, Kenya, Laos,
Lesotho, Lesser Antilles, Liberia, Madagascar, Malawi,
Malaysia (Borneo, Peninsula), Mali, Mauritius, Mexico,
Mozambique, Nepal, Nicaragua, Niger, Nigeria, Pakistan,
C
26f -27 Tribes & Genera Acro 18/7/97 7:33 Page 287
A
E
C
D
B
Plate 105. Pistia. A, habit in flower with stolons × 2/3; B, inflorescence, front view × 6; C, inflorescence, side view, longitudinal section ×
6; D, fruit × 4; E, seed × 8. Pistia stratiotes: A, FTEA Araceae 67, Fig. 17 (1985); B–E, Giles & Woolliams s.n., Cult. Kew 1963–41001 (Kew
spirit collection 29047.737).
PISTIEAE : PISTIA
287
26f -27 Tribes & Genera Acro 18/7/97 7:33 Page 288
105. Pistia
Panama, Papua New Guinea, Paraguay, Peru, Philippines,
Puerto Rico, Senegal, Sierra Leone, Somalia, South Africa, Sri
Lanka, Sudan, Surinam, Swaziland, Tanzania, Thailand,
Togo, Trinidad, Uganda, USA, Uruguay, Venezuela, Vietnam,
Zaïre, Zambia, Zimbabwe.
ECOLOGY: tropical wetlands; floating aquatic in open, tranquil, freshwater habitats.
NOTE: We have followed Engler (1920a) in our interpreta-
288
THE GENERA OF ARACEAE
tion of the structure of the male flowers, which is supported by new developmental and anatomical studies
(French 1986a, Buzgó 1994).
ETYMOLOGY: Greek pister (hollow, trough, in the sense of
a drinking trough).
TAXONOMIC ACCOUNTS: Engler (1920a), Bogner (1975),
Nicolson (1979), Sivadasan (1982), Mayo (1985a, 1986a),
Hay (1990a).
26f -27 Tribes & Genera Acro 18/7/97 7:33 Page 289
C
27 D E S C R I P T I O N O F A C O R A C E A E
Family Acoraceae
Family Acoraceae C. Agardh, Aphor. Bot. 133 (1822,
“Acoroideae ”).
One genus, distributed throughout the northern hemisphere,
temperate to tropical latitudes.
C
Acorus
Acorus L., Sp. Pl. 324 (1753). TYPE: A. calamus L.
Laticifers absent, raphides absent. HABIT: herbs, stem a
repent, much-branched, lacunose rhizome with aromatic oil
cells. LEAVES: distichous, unifacial, ensiform, not differentiated into petiole and blade, intravaginal squamules
present in leaf axils; primary veins parallel, higher order
venation parallel. INFLORESCENCE: solitary, terminal, borne
laterally on leaf-like scape, continuation shoot arising in axil
of leaf preceding spathe. SPATHE: much longer than spadix,
erect, persistent, appearing merely as a vertical extension of
the leaf-like peduncle. SPADIX: jutting out at an angle from
peduncle, conoid and finger-like or slender and tail-like.
FLOWERS: bisexual, perigoniate, densely arranged, bractless, 3-merous; tepals 6, in 2 whorls of 3, thin, fornicate.
STAMENS: 6, in 2 whorls of 3, free, filaments linear-oblong,
anthers introrse, thecae rounded-elliptic, subopposite, dehisc-
ing by longitudinal slit, connective inconspicuous. POLLEN:
monosulcate to subulcerate, ellipsoid, small (mean 18 µm;
range 15–20 µm), exine shallowly and remotely or more
densely foveolate, otherwise psilate, apertural exine subpsilate. GYNOECIUM: obconic-cylindric, slightly exceeding
tepals, 2–3-locular, ovules several per locule, pendent,
orthotropous, both integuments bearing trichomes, inner
integument longer than outer and forming micropyle, placenta apical, stigma minute, sessile. BERRY: oblong-obovoid
with thin, leathery pericarp, enclosed by tepals, 1–5(–9)seeded, whitish with brownish stigma remnant when fresh,
soon drying to straw-brown. SEED: oblong to ellipsoid,
testa light brown, foveolate (A. calamus) or smooth (A.
gramineus), long integumentary trichomes present (A.
gramineus) or absent, embryo axile, cylindric or conoid
(A. gramineus), perisperm present, endosperm copious.
See Plates 106, 130D.
CHROMOSOMES: 2n = 22, 24, 36, 44, 48.
DISTRIBUTION: 2(–4) spp.; temperate to subtropical Asia
and North America; introduced and naturalized in Europe.
ECOLOGY: temperate to tropical wetlands, up to 1100m alt.
in central Europe and up to 2600m alt. in China; helophyte,
marshes, streams, ponds, swampy sites, pastures, meadows.
ETYMOLOGY: akoron, an ancient Greek plant name.
TAXONOMIC ACCOUNTS: Engler (1905), Huttleston (1953),
Röst (1978, 1979a, b), Röst & Bos (1979), Riedl (1977–1979),
Sivadasan (1982), Grayum (1987).
ACORACEAE : ACORUS
289
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C
M
K
L
F
A
H
J
G
E
D
B
Plate 106. Acorus. A, habit × 1/6; B, base of plant and rhizome × 2/3; C, detail of leaf venation × 3; D, inflorescence × 2/3; E, detail of culm
× 3; F, detail of spadix × 5; G, flower with perigone × 8; H, flower, perigone removed × 8; J, gynoecium, longitudinal section × 8; K, berry
× 8; L, berry, transverse section × 8; M, immature seed × 100. Acorus calamus: A, Birch Wolfe Herb. (K); B, Turrill s.n. (K); C–D, Mitchell
1143 (K); E–J, M, Barnes 1629 (Kew spirit collection 6913); K–L, Licent 1473 (K).
290
THE GENERA OF ARACEAE
C
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