This large flowered, dramatic Dendrobium (the pseudobulbs are now over 1m in length) is native to the Eastern Himalayas from Assam through China, Thailand, Laos and Vietnam. We find it does best grown warm (we give it a minimum of 16C) where it seems to flower well without a marked rest period. The long pseudobulbs are particularly attractive with their covering of dark hairs. Flowers are produced in groups from the older pseudobulbs and so as the plant matures the flower count keeps increasing.
On our expeditions to Laos we have found its habitat in evergreen forest with hot wet summers and dryer cooler winters although dew is significant in the dry season leaving the forest damp every morning. It grows amongst the white Rhododendron lyi which it mimics, and is pollinated by a large bumble bee (Bombus eximius) that is hoping it is a rhododendron flower full of nectar. The orchid flowers before the rhododendron as bees that have seen both are not so easily fooled. The research, which I first read in the nineteen eighties, is really thorough and left a strong impression on a younger me.
(reference – Kjellsson, Gösta & Rasmussen, Finn & Dupuy, David. (1985). Pollination of Dendrobium infundibulum, Cymbidium insigne (Orchidaceae) and Rhododendron lyi (Ericaceae) by Bombus eximius (Apidae) in Thailand: a possible case of floral mimicry. Journal of Tropical Ecology. 1. 289 – 302.)
The species flowers several times each year and the individual flowers, although looking papery, last for two months.