J. D. Hooker et Thomson
Description
A non-photosynthetic, root-parasitic herb of the eastern Himalaya and East Asia, recorded from China, Taiwan, Nepal, India, Bhutan, Japan and Myanmar, with about 711 GBIF occurrences (a few outlying entries reflect data errors). It parasitises the roots of woody Ericaceae, particularly Rhododendron and Gaultheria, and is found in subalpine shrubberies, forest margins and moist thicket floors, generally between about 2700 and 4000 m. The illustrated plant was photographed in June at Chognam in Bhutan at around 3240 m, a typical rhododendron-dominated montane habitat.
Lacking chlorophyll, the plant draws all nutrition from its host. It arises from a swollen, tuberous, scale-covered basal organ attached to the host root, from which emerge fleshy, erect, unbranched stems coloured purplish-brown, yellowish or reddish and clothed only in small scale-leaves. The inflorescence is a dense, cylindrical, many-flowered terminal spike. Each flower is subtended by a bract and has a short cup-like calyx and a two-lipped, tubular corolla in dull purple to brownish-yellow, with a hooded upper lip and a shorter spreading lower lip; four didynamous stamens are inserted in the tube. The superior ovary ripens into a capsule packed with numerous minute, dust-like seeds adapted to wind dispersal.
Accepted by POWO and GBIF, B. himalaica is one of a small genus of broomrape relatives specialised on ericaceous hosts. Its life cycle is intimately governed by host availability and the germination of its tiny seeds in response to host-root chemical cues. Because it depends entirely on healthy Rhododendron-rich communities, it serves as an indicator of intact subalpine ericaceous vegetation. It is widespread but inconspicuous and locally sporadic; no significant conservation concern is recognised at present.
Author: J. D. Hooker et Thomson · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Beck monograph of Orobanchaceae