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Several ecophysiological observations in
Genlisea
by
Miloslav Studnicka , Botanic Gardens, 460 01 Libe rec ,
Czech Repu blic
Thanks to successful cultivation of Genlisea species, it is possible to comp lement
field research with important details . This can be helpful particularly in acq uiring
bett er knowledge oflife functions . Six species (G. fi liformis, G. hispidula, G. pygmaea,
G. rep ens, G. roraimensis and G. violacea) are cultivated in the Bot. Gardens Libe rec
(CR).
According to occasional field observations ,Genlis ea species often grow in water.
Never t heless , one must question ifthey are true aq uatic plants or if they are in some
sense semiterrestrial. We can look for st omat a which are cons idered special aerial
orga ns. Stomata are mostly absent in submerged pla nts but there are several
except ions h aving rudimentary stomata.
Lloyd (1942) writes: "All the species are small plants which inhabit swampy places
and apparently live mostly submersed in shallow water; only the inflorescence, as in
Utricularia , projecting above the surface. This is to be inferred from t h e abs ence of
st oma t a
". In contradiction to this opinion, Elsa Fromm-Trinta (1979) published
phot ogr aph s of distinct stomata in G. filiformis, G. pygmaea, G. repens and G. violac ea.
She writes: "Stomata are only in the dorsal epidermis of G. repens and G. pygmaea."
I have also stud ied G. repens and G. pygmae and G. hispidul a and G. rora imensis . I
have also found stomata, but I have been surprised by observing the stomata only in
the lower (abaxial) surface ofleaves. According to Czech authorities (e. g. Dostli11954 ,
et c. ), the "dorsal" near the upper surface of a leaf. Th e t erm "dorsal" is evidently used
in different meaning in botany!
It is better to say that stomata occur in the abaxial surface of leav es . That is
however a n arrangem ent wh ich is normal in many purely terrestrial plants . I have
found both open and closed stomata in various specimens ofGenlisea . I believe,therefore
that stomata are working and are not r udimentary. Genlisea species are semiterrestrial plants, green leaves of which are aerial organs. They can survive also below water
for long periods, but I h ave never observed morphologica l ada pt ations to t hat cond iti on . Many se mite rrestrial Utricularias t U. graminifolia, U. prehensilis etc .) make
shor t ae rial terrestrial leaves and very long ribbon-shaped aqua ti c leaves. These
plants, re lated to Genlisea , are probably more adapted to aquatic life in comp arison
wit h Genlisea .
Th e inv estigation of traps in cultivated specimens is of interest, I have compared
two most different species, namely G. hi spidula and G. pygmaea . You find only one type
of trap in G. hispidula, but in G. pygmaea there a re two evidently different type s of
traps . The traps ofthe first type are very long, with very small ves icles, narrow necks
and with long arms . They are in a vertical position. The traps of the second type are
shor t, but the ve sicles are three times larger and the neck s are three times wid er than
in the firs t type . Th e arms are also very short, wit h fewer windings . Th ese trap s are
more or less horizontal.
Analysis of contents in the traps has bee n sur prisin g. The traps of G. hisp id ul a
hav e been quite em pty, but the traps ofG. pygmaea , cul tivated in the same soil a nd in
the same condit ions, have been full of pr ey. In the vesicles I have see n remains oftwo
species ofNemathelmintes, Arthropoda, a nd al so single-cell a lgae (Baccillari ophyzae
and Desmidi ales). In ne cks, I have fr equently observed livin g Nematodes . Com paring
Volume 25 Mar ch 1996
15
the two studied sp ecies , we can draw two conclusions:
1. There is sp ecia lisation of different prey in the species, because only one ofthem h as
cons umed prey from the uniform culture system..
2. Prey is not wholly ne cessary because all specim ens of G. hispidula (wit hout any
prey in traps) have been in good form and fr equently flowered .
A further st ep of my research has been connected with the published h ypoth esis
about active capture of prey in Genl isea (Meyers- Rice 1994 ). I hav e pe rformed a simply
experiment, using intact specimens of G. pygmaea . The plant was removed from soil
and traps ofthe on e were submerged into water with very finely di spersed particles of
a red pigment. After 20 minutes . . . sev eral tr aps of both small and lar ge types were
cut and observed microscopi cally. I h ave never observed a ny r ed gr ains or soil particles
in the traps.I could not confirm Meyers-Rice 's hypothesi s this way. I beli eve that t he
traps are passive. The soil particles in traps, mentioned in lit er atur e (J u niper, Robins
and Joel 1989), could be pu shed to the vesicl es by captured animals or in consequence
of artifici al comp r essions during transp ort of the pl ants from the wild.
The fact that gla nds in the vesicles in Genlisea are different from the active traps
in Utr icul aria als o speaks against the hypothesis ; especially the group oftwo-armed
glands, which should be respons ible for the pumping of wa ter in Utri cul ar ia , is absent
in Genlisea . Because the glands in the vesicl es ofGenlisea ar e ve ry simila r to t he glands
k nown in Pinguicula, the speed of absorption is probab ly comparab le .
I can als o comment on the description of growth in the traps ofGenlisea , published
by Lloyd (1942). How do th e traps penetrate into soil? According to Lloyd , in the begin
the Genlisea trap grows like a root. The meristem is also in the a pex of the tubular
organ, which is covered by mucila ge produced by numerous very small glands . Most
in teresting is t he last part of developmen t , wh en ar ms st ar t to grow. According t o
Lloyd , there is rotation ofthe growing arms . I have found two near-by trap s with arms
scr ewe d one in t o another. It seems 'to be a demonstration, that the ar ms pen etrate into
soil like an auger into wood .
Literature:
Dostal J . (1954): The key to the comp lete
flora of the tSR.Prague, !The morphological
dictionary, p. 10/.
,.,.-- -- --, 0
10
20
30
40
50
Fromm-Trinta E . (1979): Rev is ao das
E sp eci es do Genero Genlisea ST. HIL.
(Lent ibulariacea e) das Regi6es sudes t e e
sul do Bra sil. - Rodriguesi a , Rio de J aneiro,
31/49: 17 -139.
Juniper B. K , Robins R. J. and Joel D. M.
(1989): Th e carnivor ous plant s.- London et c.
Lloyd F . E . (1942): The carnivorous plants .r eprint 1976 , Toronto.
Meyer s-Rice B. (1994): Are Genlise a traps
active? A crude calcul ation .- Carniv. PI.
Newslett., Fullerton, 23: 40-42 .
Figure 3. Genlisea pygmaea on a s cale in
millimetres . Two differen t types of traps in
one plant. (Dra wing by R. Novotna. )
16
Ca rnivorous Plant News lette r
Figure 1. Genlisea hispidula
Figure 2. Genlisea pygmaea
were usedto investiaate captu re of prey in comoarable
conditions. Their favourite menu must be different.
REFERENCE:
Studnička M. (1996): Several ecophysiological
observations in Genlisea.- Carniv. Pl. Newslett.,
Fullerton, 25: 14-16.
(This historically important article
describes the trap dimorphism of
Genlisea for the first time.)