Download Print this article

Bothalia 29,2: 2 5 3 - 2 6 6 (1999)
Notes on African plants
VARIOUS AUTHORS
CONVOLVULACEAE
NOTES O N D IC H O N D R A A N D XENOSTEGIA IN SO U T H E R N AFRICA
Dichondra micrantha
In the revision of the South African Convolvulaceae
by Meeuse (1957), the name Dichondra repens J.R. &
G.Forst. (1776) is accepted for the only species of the
genus Dichondra occurring in the region. This name is
also accepted by Verdcourt (1963) for tropical East
Africa, by Gonsalves (1987) for the Flora zambesiaca
region, by Lejoly & Lisowski (1993) for Central Africa
and by Welman (1993) for southern Africa, as well as by
various other authors in publications dealing with the
Convolvulaceae or the weeds in Africa south of the
Sahara.
In South Africa this small procumbent, creeping herb
is often cultivated as a ground cover or soil binder and
sold under various names e.g. dewdrop lawn, wonder
lawn. It grows as a weed in moist places in grassland and
in cultivated and other disturbed areas and is recorded
from isolated localities in mainly the eastern and north­
ern parts of South Africa: so far there are no records in
PRE from Swaziland.
Tharp & Johnston (1961) indicated that D. repens is
endemic to Australia, Tasmania and New Zealand and
that records from other areas under this name belong to
various other species, chiefly D. micrantha Urban.
Lawalree (1970) showed that the species that is wide­
spread throughout the warmer regions of both hemi­
spheres, is actually D. micrantha Urban which is acci­
dentally or voluntarily spread by man as a weed or horti­
cultural subject. He listed two important differences
between the two species. In D. micrantha the peduncle is
3-20 mm long and recurved at maturity; the sepals are
rounded or obtuse, shorter than 2.5 mm and shorter than
the fruit. In D. repens the peduncle is 10-40 mm long
and remains erect; the sepals are acute-acuminate, up to
5 mm long and longer than the fruit.
Bailey & Bailey (1977) accepted the name D. m icran­
tha for the commonly cultivated Dichondra, although the
name D. repens is still used in the horticultural trade.
Forde (1978) proved that the species cultivated in lawns
in New Zealand is D. micrantha. She pointed out that it
differs from the native D. repens by the virtually
glabrous upper leaf surfaces, the appressed silky pubes­
cence below, the short-stalked flowers with violet
anthers, the narrow pointed corolla lobes and the fruits
greatly exceeding the calyx at maturity. The abundant
and usually self-pollinated flowers are mostly hidden
below the leaves on very short peduncles, which later
recurve almost to bury the swollen indehiscent fruits.
Austin (1998) reported that Sebsebe Demissew and
Austin investigated specimens of Dichondra from Africa
and compared them with lawn seed sold by American
companies. It was found that the commercial plants as
well as all African specimens are D. micrantha. He
pointed out that only two species of Dichondra are native
to the Old World and they both occur in New Zealand
and Australia. All other species of Dichondra are indige­
nous to the New World. D. micrantha is probably origi­
nally from North America, though the type was collected
in Cuba where apparently it was already naturalised. It
has been cultivated and distributed by man for the past
200 years and as a result is now widespread in both
hemispheres, particularly in the warmer regions. It is
used as a herbal medicine in China, presumably because
of its resemblance to the medicinal Centella asiatica (L.)
Urban (Apiaceae).
Dichondra in southern Africa should be listed as fol­
lows:
D ichondra m ic ran th a Urban in Symbolae Antillanae 9: 243 (1924). Type: Cuba. Oriente province. Taco
Bay, E.L.Ekman 3851a (S. holo.; B?. iso.).
D repens auctt., non J.R. & G Forst.: 40. t 20 (1776).
Xenostegia tridentata subsp. angustifolia
In an article by Meeuse & W'elman in Bothalia
(1996), Meeuse published the combination Xenostegia
tridentata (L.) Austin & Staples subsp. angustifolia
(Jacq.) A.Meeuse. This was superfluous as this combina­
tion had previously been published by Lejoly &
Lisowski in 1993.
The correct author citation is as follows:
Xenostegia trid e n ta ta (L.) Austin & Staples
subsp. angustifolia (Jacq.) Lejoly & Lisowski in Fragmenta Floristica et Geobotanica 38: 379 (1993).
Ipom oea angu stifolia Jacq : 367 (1 7 8 9 ) Iconotype: Jacq., Icones
plantarum ranorum 2: 10. t 317 ( 1 7 8 6 - 1 7 9 3 ), based on a specim en
from Guinee
Lejoly & Lisowski (1993) also published the new
combination of another subspecies of X. tridentata
namely subsp. alatipes (Dammer) Lejoly & Lisowski.
This subspecies from tropical Africa has so far not been
recorded for southern Africa.
254
Bothalia 29,2 (1999)
ACKNOW LEDGEMENT
M EEUSE, A D J . 1957. The South African Convolvulaceae. B othalia
6: 6 4 1 -7 9 2 .
Dr D. Austin (Florida, United States) is thanked for
valuable comments on Dichondra.
M EEU SE, A.D.J. & W E LM A N , W.G. 1996. Convolvulaceae: new
records, name changes and a new combination in southern
Africa. Bothalia 26: 4 6 -5 0 .
THARP, B C. & JO H N ST O N , M.C. 1961. Recharacterisation o f
D ichondra (C onvolvulaceae) and a revision o f the North
American species. B rittonia 13: 3 4 6 -3 6 0 .
REFERENCES
A U S T IN , D.F. 1998. The indiscriminate vector: human distribution o f
D ich o n d ra m icrantha (C onvolvulaceae). E conom ic B otany 52:
8 8 -1 0 6 .
BAILEY, L H. & BAILEY, E.Z. 1977. H ortus Third, a con cise d ic tio ­
nary> o f p la n ts c u ltiv a te d in the U nited States a n d C anada.
M acmillan, N e w York.
FO RD E , M B 1978. The cultivated dichondra. New Z ea la n d Journal
o f B o ta n y 16: 2 8 3 -2 8 5 .
FO RSTER, J R & FO RSTER , G. 1776. C haracteres gene rum p la n ­
tarum. White, Cadell & Elmsly, London.
G O N S A L V E S . M L. 1987. Convolvulaceae. In E Launert. Flora
z a m b esia c a . Vol. 8,1 Flora Zambesiaca M anaging Committee,
London.
U R B A N , I 1924 Plantae cubenses Ekman II. S y m bo la e A ntillanae 9:
243.
VERDCOURT. B. 1963. Convolvulaceae In C.E Hubbard & E. MilneRedhead, Flora o f tro p ic a l E ast A frica. Crown Agents, London
V O N JACQUIN, N.J.
Vienna.
1 7 8 6 -1 7 9 3 . leon es pla n ta ru m rariorum 2.
V O N JA C QU IN , N.J. 1789. C ollectanea au stria ca a d botanu um 2.
Vienna.
W E L M A N , W.G. 1993. Convolvulaceae In T H Arnold & B.C. de
Wet, Plants o f southern Africa: nam es and distribution
M em oirs o f the B otanical Survey o f South A frica No. 62.
LAW ALREE, A. 1970. Definition, aire et mode de dissemination de
D ich o n d ra m icrantha Urban (C onvolvulaceae). A cta Botanica
N eerla n d ica 19: 7 1 7 -7 2 1 .
LEJOLY, J. & L ISOW SKI, S. 1993. Les C onvolvulaceae dans la flore
d ’Afrique Centrale (Zaire, Rwanda, Burundi). F ragm enta
F loristica e t G eo b o ta n ic a 38: 3 5 1 -4 0 0 .
W.G. W E L M A N *
* National Botanical Institute, Private Bag X I 01, 0001 Pretoria.
MS. received: 1998-06-12.
CRASSULACEAE
CRASSULA M APU TEN S1S: A NEW R ECO RD FOR THE FSA REGION
At the time of its First description (R. Fernandes 1978),
and subsequent treatment in the Flora zambesiaca (R.
Fernandes 1983), Crassula maputensis was only known
from southern Mozambique and Inhaca Island. The type
specimen was recorded from Maputo Province, on the
road between Salamanga and Ponta do Ouro. Its possible
occurrence in KwaZulu-Natal was nevertheless suspect­
ed (R. Fernandes 1983).
Recent botanical collecting in KwaZulu-Natal and a
study of herbarium collections in PRE. PRU, NH and
LMU, have confirmed that C. maputensis is indeed present
in northeastern KwaZulu-Natal (Maputaland). The latter
area is part of the Maputaland Centre of Plant Endemism,
with C. maputensis being one of more than 230 plant
species or infraspecific taxa which are more or less restrict­
ed to this region (Van Wyk 1996). The known geographi­
cal distribution of C. maputensis is shown in Figure 1.
ful (Quarternary); and that its nearest relative, C. expansa,
is still extant.
Crassula maputensis ditfers from C. expansa (Figures
2 & 3) by the broader (1.5-0.7 mm), flat, obtuse leaves,
by the solitary axillary flowers which are usually borne
all along the stems, and by the flowers with petals
1.5-2.0 mm wide. In C. expansa the leaves tend to be
narrower, usually 1-2 mm, and more terete, particularly
in subsp. expansa; the flowers are borne mainly on the
distal parts of the stems, and are smaller with the petals
1.0-1.25 mm wide. Additional distinguishing characters
are supplied by Fernandes (1983).
14
12
p
16
18
20
22
24
26
r
28
y
t
- - V — ♦— t
i
32
.
]
J
. V
, 8 ■
20
\
t
34
f
30
:
•
T
18
■ ^
'
20
V.
Y
.
*
,
r
1
1
t
22
In southern African herbaria specimens of C. maputen­
sis were sometimes filed under C. expansa Dryand.. prob­
ably the nearest relative of our species. In fact, Tolken
(1985) does not recognise C. maputensis as a separate
species, but considers it merely as an extreme form of C.
expansa subsp. expansa characterised by somewhat larg­
er leaves and larger flowers. However, based on evidence
from geographical distribution, ecology and macromorphology, the recognition of C. maputensis as a distinct
species seems to be justified. In accordance with many
other Maputaland Centre endemics, C. maputensis
appears to be of fairly recent diversification (neoendem­
ic), an impression supported by the fact that it is confined
to the Maputaland coastal plain which is relatively youth­
4
•
■ \ *
241
t
u
26
r
* -i
‘ .
28
1
• *
a. .
t-
‘
30
.
;
;
*
\ |
. .j-
i'
n
\
I
l
’
•
/
*■ t
4 •
r\i
}
*
t
V
y :
> >
\
*
-
J
i
■
f
.1
■i
26
t .■
.
281
V
r
1
A h
I
•
*
•
7
■
■
■
V
I i ) /
•
•
/ .
30
32
1 V
• _ «•
34
to
1 « M «
r - t - g V i
12
14
TJ v
t'
'
r
16
18
24
|
'*
• V \ - , - ]•
* * * * *
V»«
f• i
v y .-— •
20
‘
*
t
*
<
(32
•
>
22
f
24
26
28
X
32
34
_
*
34
36*
FIGURE I.— Known distribution o f C rassula m aputensis based on
collections at PRE, NH and LMU