The following article was written for the Orchid Species Bulletin published by the Orchid Species Society, which is based in Brisbane, Queensland in August 2005.
Bear in mind that any cultivation notes refer to the sub-tropical conditions of Southern Queensland, Australia.
Coelogyne pulverula
Teijsm. & Binn.
is perhaps better known as Coel.
dayana Rchb.f. Johannes
Teijsmann and Simon Binnendijk described Coel.
pulverula in Natuurkundig Tijdschrift
voor Nederlandsch-Indië in 1862. The
specific epithet comes from the Latin pulvereus
(powdery, dust-like) and the diminutive suffix –ula
and refers to the powdery appearance
of the flower. Heinrich Gustav
Reichenbach published Coel. dayana in
the Gardeners' Chronicle in 1884, so
this specific name is a later synonym.
A large epiphytic
plant, Coel. pulverula has clustered
pseudobulbs that are borne along a creeping rhizome up to 1.5 cm apart.
The shallowly grooved spindle-shaped to narrowly conical pseudobulbs are
7-25 cm long and 2 cm in diameter near the base.
The apex of each pseudobulb bears two oblanceolate to elliptic leaves
that are 25-65 cm long and 4.5-11 cm broad with a 6-15 cm long stalk.
Inflorescences are produced from the centre of the newly developing
growth before the leaves are halfway developed.
The peduncle is enclosed in bracts and the pendulous straight to zigzag
rachis is 25-110 cm long. Opening
simultaneously the raceme bears 10-55 flowers that are about 5 cm across at 2.5
cm intervals. The flowers have pale
to light yellowish brown to greenish ochre sepals and petals.
Its tubular white lip has the front of the side-lobes banded brown and
the inside of the side-lobes brown to dark brown with white nerves and a white
margin. The white mid-lobe often has
a narrow brown cross band over the longitudinal keels.
Distributed in
southern Thailand, Peninsular Malaysia, Borneo
and
Sumatra, Coel.
pulverula is found between 275-1,900 m.
It
grows on the trunks and large branches of
trees in lowland rain forest and lower montane forests.
Sometimes it can be found on rocks often near streams and rivers.
Gunnar Seidenfaden and Jeffrey Wood (1992) say that Coel.
pulverula "may be easily cultivated in the lowlands, but is not very
free-flowering in
Singapore".
This species seems to require intermediate conditions with a cooler drier
winter rest, which seems to help promote flowering.
Grow it under about 60-70% shade with high humidity and good air
circulation. Use a well-drained
medium and water it regularly during the warmer months.
Reduce the watering frequency while it is not actively growing but do not
allow it to remain dry at the roots for long periods.
I recommend a winter minimum of 12 oC.