One striking feature of this Thai orchid species
is the unusually long spur-like mentum. ‘Cumulatum’ refers to its tendency
to accumulate many flowers on a short stalk.
Many large and colourful wild Dendrobium orchids of the
Chiang Mai area bloom in the hot dry season (March-April). The Dendrobium
blossom of the rainy season (May-September) tend to be smaller, but there
are exceptions. Right now you will find the pink or lavender Dendrobium
cumulatum (Orchidaceae) in blossom both downtown and at Dokmai Garden. An
English vernacular name is ‘The Crowded-Inflorescence Dendrobium’ which is a
direct translation of ‘cumulatum’. Since this is quite an exceptional plant
and a nice blotch of colour when most other Dendrobium are green, I think
‘rain orchid’ is a better name. August and September are the rainiest months
in Chiang Mai.
It is found from eastern Himalaya all the way down to Borneo, and although I
have never seen it in nature, judging from its behaviour at Dokmai Garden it
seems adapted to wet environments. Unfortunately the literature does not
reveal much of its habitat, and we ask our readers to share knowledge on
this matter, so that the Orchid Ark can grow it under perfect conditions.