Cowley
Description
Roscoea nepalensis is a tuberous-rooted herb of the western and central Himalaya, recorded by GBIF chiefly from Nepal and adjoining SW China, with a modest tally of around 19 georeferenced occurrences reflecting its localised distribution. Unlike most members of the ginger family, Roscoea is montane and temperate rather than tropical, and this species inhabits open grassy slopes, forest margins and meadows of the middle hills. The photographed populations in West Nepal at Talphi (2,830 m, June) and Roha (2,750 m, July) are characteristic, the plants emerging and flowering with the onset of the summer monsoon at around 2,700–2,900 m.
The plant is a deciduous perennial arising from fleshy fascicled roots, with an erect leafy pseudostem formed by the imbricate leaf sheaths. The leaves are lanceolate to oblong-lanceolate, glabrous, sheathing at the base. The flowers are produced in a terminal spike, exserted from or partly enclosed by the leaf sheaths, and are strongly zygomorphic and orchid-like: a tubular calyx, a trilobed corolla with a hooded dorsal lobe, prominent petaloid lateral staminodes, and a large, deflexed, bilobed labellum, typically purple to violet. The fruit is an elongate capsule containing arillate seeds.
The family is given verbatim as Zingiberacaea (a misspelling of Zingiberaceae). Roscoea is a remarkable case of a predominantly tropical lineage that has radiated into cool Himalayan and Sino-Himalayan highlands, its summer-deciduous, tuberous habit being an adaptation to a markedly seasonal monsoon climate. The orchid-like floral architecture promotes pollination by long-tongued insects. The genus is of considerable horticultural interest, and species delimitation within the R. purpurea complex, to which R. nepalensis is allied, has been clarified by molecular and morphological study.
Author: Cowley · Sources: POWO (Kew), Flora of Nepal, GBIF, Flora of China Vol. 24, Cowley: The Genus Roscoea (Kew, 2007)