/ N U . J O U R N A L O F S C I E N C E , N a t . S c i. & T e c h . , t . X V I I I , n ° l - 2 0 0 2

NEW ORCHIDS IN THE FLORA OF VIETNAM 2.
THE GENUS PLOCOGLOTTIS BLUME
L eonid V . A veryan ov
Komarov B otanical Institute, Russian Academ y o f Sciences
The genus P lo c o g lo ttis Blume includes about 45 species, distributed mainly in
Vlalesia ranging from the south of Indochinese Peninsula to New Guinea and tropical
Pacific islands. Mostly they are large terrestrial herbs of lowland shady forests growing
)n deep soils rich in humus.
The lip in flower of P lo c o g lo tbis species is connected to the lower
part of the column by two stretching
elastic flanges. On flower opening lip
IS forced down by a trigger to the lat­
eral sepals. Light touch of the lip by
insect releases trigger and lip springs
up to column pressing expected polli­
nator toward the column. This unusual
mechanism of orchid flower pollination
is unique among Vietnamese orchids.
P lo c o g lo ttis Blume, 1825, Bijdr.: 380.
Key for identification of the species
in the flora of Vietnam.
1. Pseudobulbs cylindrical, 11.5 cm thick, oblique, their basal por­
tions appear as a thick creeping rhi­
zome, apical part ascending, bearing
one leaf; inflorescence commonly less
th at 0.5 m long; flower bracts ovate; lip
convex hemispherical, cup-like, about 5
mm wide... 1. p. javanica
2. Pseudobulbs ovate or bottleshaped, 2-4 cm thick, vertical, closely

E cology: Shady, humid, broad-leaved evergreen prim ary subm ontane tropical forest
on deep soils rich in humus mainly on granite and gneiss at elevations 700-900 m a.s.l.
Rare.


N e w orchids in the flo r a o f V i e t n a m 2.

3

D is trib u tio n : Vietnam: K hanh Hoa prov., Khanh Vinh distr. (about 8 km from
K hanh Le mull, to the w along Lieng Ly river), fig. 1.- Andaman Islands, Malaya,
Sum atra, Java, Kalimantan.
S tu d ie d h e r b a r iu m sa m p le s: Southern Vietnam, Prov. K hanh Hoa, Distr.
K hanh Vinh, about 8 km from K hanh Le mun. to the w along Lieng Ly river at elev.
700-850 m a.s.l. Open prim ary evergreen subm ountain forest on river side granite slopes
above waterfall. Terrestrial herb in shady place. Occasional. 15 XII 1995,Averyanov L.
& N. T.Hiep, VH 2483/a (LE).
S h o rt d e s c rip tio n : T e r r e s tr ia l c re e p in g h e rb . P s e u d o b u lb s slender, oneleaved, about 10 cm long and 1-1.5 cm thick, when young covered with long sheaths,
oblique, their basal portions appear as a thick creeping rhizome. L eaves pleated, with
several prominent longitudinal veins, stalk 10-20 cm long, slender, leaf blade 20-35 by
8-12 cm. In flo re sc e n c e from middle p art of pseudobulb, scape 20-50 cm long, erect,
rachis bearing a succession of many flowers, a few open at one time. F lo w er b ra c ts
green, ovate, about 8 mm long. F lo w e rs odorless. Sepals and lateral petals spreading,
yellow with irregular dull red purple marks; se p a ls narrowly ovate, 15 by 6 mm, suddenly
narrowed to a sharp tip; p e ta ls lanceolate, about. 12 by 2 mm. L ip light lemon-yellow
with small purple marks at the base, convex, hemispherical, cup-like, about 5 rnm wide, 4
mm long, broader than long, ending in a reflexed narrow tooth-like tip, lip joined to the
sides and tip of the short column foot, thus forming a sac at the base, with an elastic joint
that springs when the lip is touched. C o lu m n dull yellow, white toward the base, with
longitudinal short purple stripe on each side of stigma, dull red-purple marked on dorsal


Fig. 3.
P lo co g lo ttis b o k o re n sis (G a g n e p .) S eid en f.
Hieu, et al. VH 6Ậ35).

(drawn from Averyanov, Hiep,

a - flowering plant; b - flattened sepals and lateral petal;
c-d - lip, view from above and from below;
e - column with prim ary lip position, side views;
f - column frontal view; g - pollinarium.
Short d escrip tio n : T errestrial herb with clustered vertical pseudobulbs. P se u ­
d ob u lb s ovate or bottle-shaped, 10-12 cm tall and 2-4 cm thick, Closely arranged on thin
rhizome, apically bear many-leaved stem up to 1 m tall. Young pseudobulbs covered with
several sheaths, old one naked. L eaves pleated, sessile, with several indistinct veins, leaf
blade (3)5-10 by 2-3.5 cm. In flo rescen ce from base of pseudobulb, scape 0.5-1.5 m long,
erect, rachis bearing a succession of many flowers, a few open at one time. F low er bracts


N e w orch id s in the flo r a o f V i e t n a m 2.

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green, lanceolate, 1.5-2 CM1 long. S ep als and la te ra l p e ta ls spreading, yellow with irreg­
ular dull red purple marks; se p a ls narrowly ovate, 12-15 by 6-8 mm, suddenly narrowed
to a sharp tip; p e ta ls broadly lanceolate, about 14 by 3 mm. L ip yellowish-white, curved,
about 10 mm wide, 7-8 mm long, distinctly broader th an long, ending in a narrow to o th ­
like tip, lip joined to the sides and tip of the short column foot, thus forming a sac at the
base, with an elastic joint th at springs when the lip is touched. C o lu m n yellowish-white,
surface. 6-7 mm long and 4-4.5 mm wide. A n th e r c u p and s tig m a dull yellow. P o llin ia