Rchb.f.
Description
Bulbophyllum retusiusculum is a widespread epiphytic orchid ranging from the eastern Himalayas (Nepal, northeast India, Bhutan) through Myanmar, southern China, Taiwan, Vietnam, and Thailand. GBIF records document over 550 occurrences across this range. The species inhabits broadleaved and mixed forests at 800–2,500 m elevation, growing on tree trunks and branches in moderately humid conditions.
The pseudobulbs are narrowly ovoid to cylindrical, 1–2 cm tall, clustered on a short rhizome. Each bears a single, oblong-elliptic, leathery leaf 4–10 cm long with a slightly retuse (shallowly notched) apex — the feature reflected in the specific epithet 'retusiusculum'. The inflorescence is an erect to arching, densely many-flowered raceme 5–15 cm long. The flowers are minute, 3–4 mm across, arranged in a dense, cylindrical spike, typically pale yellowish-green to cream. The dorsal sepal is concave, the lateral sepals spreading, and the lip is small, fleshy, and recurved. Flowering occurs from September to November.
B. retusiusculum belongs to Bulbophyllum section Brachystachya, characterised by densely flowered, spike-like racemes. The species shows moderate morphological variation across its extensive range, particularly in flower colour and pseudobulb spacing.
Author: Rchb.f. · Sources: POWO (Kew), Flora of China Vol. 25, GBIF, Pearce & Cribb: The Orchids of Bhutan (2002)