Wall.
Description
Triosteum himalayanum is a Sino-Himalayan perennial herb distributed across China, Nepal, Bhutan, Sikkim and northern India, with GBIF aggregating around 990 occurrences. It is characteristic of the upper temperate to subalpine forest belt, recorded here from Jakar in Bhutan at 3200 m in June and the Tista valley in Sikkim at 3400 m in August. The species grows in moist shaded forest, woodland margins, scrub and tall-herb communities along streams and on cool, humus-rich slopes, typically between roughly 2500 and 4000 m, where it forms part of the shade-tolerant understorey flora.
It is an erect, softly hairy herbaceous perennial 0.4-1 m tall arising from a stout rhizome, the stems unbranched and glandular-pubescent. The leaves are opposite, large, broadly obovate to elliptic, often shortly connate at the base around the stem (perfoliate to subconnate), entire to shallowly lobed and softly hairy on both surfaces. Small tubular flowers are clustered in dense axillary and terminal verticels; the corolla is dull purplish to greenish-yellow, weakly two-lipped, and the calyx bears persistent, leafy, ciliate lobes. The most conspicuous feature is the fruit, a fleshy, bright red, bristly-hairy drupe crowned by the persistent calyx and containing three bony pyrenes.
Triosteum (horse-gentian) is a small, disjunct genus of about six species in eastern Asia and North America, now placed within an enlarged Caprifoliaceae; this striking amphi-Pacific distribution makes it a classic example of the eastern-Asian-North-American biogeographic link. T. himalayanum is widespread and locally common within its montane range and is not of conservation concern; its showy red drupes are dispersed by birds, and the rhizome has a place in regional herbal traditions.
Author: Wall. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Flora of British India (Hooker), Gould & Donoghue revision of Triosteum (Caprifoliaceae)