Dendrobium fuscescens — Orchideaceae

Dendrobium fuscescens

by GP Jürgens

Griff.

Bhutan2015 449
  Bhutan Jakar 2500m, October
Bhutan2015 450
  Bhutan Jakar 2500m, October
Bhutan2015 451
  Bhutan Jakar 2500m, October
Bhutan2012 1129
Bhutan Koma-Chu-Valley 950m, October
Bhutan2012 1131
Bhutan Koma-Chu-Valley 950m, October
Bhutan2012 1358
Bhutan Sandrup 1500m, October

Description

Dendrobium fuscescens Griff. is an epiphytic orchid of the eastern Himalaya and adjacent Indo-Burmese region, recorded by GBIF from China, India, Myanmar, Nepal and Bhutan across some 69 occurrences. It grows on the trunks and branches of trees in humid broad-leaved and mixed forests, ranging over a broad altitudinal span as shown by the Bhutanese records at Jakar around 2500 m, in the Koma-Chu valley near 950 m, and at Sandrup about 1500 m, all in October. This spread from warm temperate valleys to cooler montane forest reflects a tolerance of moist, shaded, mossy bark substrates with good air movement.

The plant produces clustered, slender, elongate cane-like pseudobulbous stems that are somewhat flattened and grooved, becoming yellowish with age. The thin-textured, lanceolate to oblong leaves are distichously arranged along the stems and are usually deciduous in the dry season, leaving the canes bare. Short lateral racemes of a few small flowers arise from nodes on the older leafless stems; the flowers are pale, often tinged greenish or brownish-yellow (the epithet fuscescens alluding to the darkening tint), with spreading lanceolate sepals and petals and a labellum bearing a hairy or papillose disc and recurved lateral lobes, the lateral sepals forming a short mentum at the column foot.

Dendrobium is one of the largest orchid genera, and D. fuscescens belongs among the slender deciduous-caned Himalayan species. It is poorly documented, with few georeferenced records, and like most epiphytic orchids it is sensitive to deforestation and collection. No formal assessment singles it out as threatened, but its dependence on intact forest canopy makes habitat protection important, and all Dendrobium are listed on CITES Appendix II.

Author: Griff. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, World Checklist of Dendrobium, Seidenfaden monograph of Orchids of Indochina

Within the same family