Culms 2--3 m tall, 0.5--1.5 cm thick; internodes lightly to densely white-waxy at first, becoming glossy dark green; nodes lightly raised, sheath scar prominent without persistent ring of hairs, purple above nodes, or above and below nodes. Culm sheaths fairly persistent, long-tapering, margins ciliate, abaxially very sparsely white-pubescent at first, adaxially apically glabrous to long-scabrous; ligule tall, fimbriate, adaxially glabrous to long-scabrous, abaxially pubescent; auricles and oral setae absent; blade long, narrow, reflexed. Leaf sheaths glabrous, margins glabrous or ciliate; ligule 3--5 mm tall; auricles absent; oral setae absent; blade thin or tough, narrowly linear-lanceolate, 8--20 x 0.6--1.5 cm, largely glabrous or the abaxial surface occasionally lightly pubescent, abaxial proximally pilose near midrib. Synflorescence on leafless branches; branches fasciculate, slender, curving. Spikelets about 1.25 cm; florets 2--3. Glumes 2, unequal; first glume about 5 mm, 1--3-veined; second glume about 7 mm, 5--7-veined; lemmas about 1 cm, similar to the second glume; anthers about 3.5 mm.
Lacks the auricles of D. intermedium, and shorter leaf sheath ligules than D. falcatum. Further study is required on the relationships to bamboos identified as D. khasianum in Nepal and Bhutan.
The name D. khasianum has been applied to many bamboos, because the absence of hairs, oral setae or other prominent features can confuse it with similar species. Even Fargesia nitida was initially misidentified as D. khasianum when first grown in the west, until it was described with a new name.
Plants of D. khasianum closely matching collections from the type locality near Shillong in the Khasia Hills of Meghalaya in NE India were being grown in the Temperate House at Kew Gardens in 1877, but by 1920 clumps, still grown as D. khasianum, had apparently been usurped by the invasive P. simonii. Most plants in cultivation in Europe under this name are H. falconeri, but at least 1 correctly identified plant was recently still in cultivation in Europe, but started flowering in 2008. Its seed has been widely distributed as D. khasianum ‘Shillong’. It is small in stature, to 2m, with leaves to 12cm, and rings of purple colour both above and below the nodes.
Plants cultivated under the name D. khasianum in the US since the 1980s are much larger, to 6m, with longer leaves to 20cm, purple colour only above the nodes, culm sheaths notably glabrous on the inside surface, and fewer branches. Its origin is unrecorded and flowers are not known, but it would appear closer to Himalayacalamus than to Drepanostachyum.
From Meghalaya State of India, and the Eastern Himalayas in Nepal and Bhutan. Type collection from Shillong Wood in Meghalaya.