Benth.
Description
Millettia pachycarpa is a robust woody climber of the eastern Himalaya and South-East Asia, ranging from Nepal, Bhutan and north-east India through Bangladesh, Myanmar, Thailand, Laos and Vietnam to southern China and Taiwan. GBIF holds around 2140 occurrences across this subtropical to warm-temperate range. It grows in broad-leaved forest, forest margins, ravines and along streams, scrambling over trees at low to middle elevations. The plant from Lingza in the Darjeeling hills of West Bengal at 1300 m in May represents a typical eastern Himalayan population, flowering in spring before the monsoon.
It is a large, woody, deciduous liana with stout twining stems. Its leaves are alternate and imparipinnate, with numerous opposite, oblong to oblong-lanceolate leaflets that are dark green and somewhat leathery, glabrescent above and finely appressed-hairy beneath. The flowers are borne in long, dense, pendulous axillary racemes or panicles, the corolla papilionaceous and lilac to purplish-pink, the standard broad and often silky-hairy outside enclosing the wing and keel petals; the stamens are diadelphous and the ovary superior. The fruit is a large, thick, woody pod (the epithet pachycarpa meaning thick-fruited), pendulous and often tuberculate, indehiscent or tardily so, with one to several large hard seeds.
Millettia belongs to tribe Millettieae of the papilionoid Fabaceae, a group much revised in recent decades with several Asian species transferred to allied genera; M. pachycarpa is retained in Millettia in current treatments. The plant is notable for its high content of rotenoids and isoflavonoids: the seeds and roots have long been used as fish poison and insecticide across its range, and it is an important source of rotenone-type compounds. Widespread and frequent in eastern Himalayan forests, it is of no conservation concern.
Author: Benth. · Sources: POWO (Kew), GBIF, Flora of China Vol. 10, Flora of Bhutan Vol. 1, Annotated Checklist of the Flowering Plants of Nepal, Geesink revision of Millettieae