(DC.) M.L.Zhang & Podlech
Description
Phyllolobium donianus (correctly P. donianum, the accepted spelling), formerly placed in Astragalus, is a Sino-Himalayan legume distributed from Nepal through northern India, Sikkim and Bhutan into south-western China, with 256 GBIF records concentrated in the central and eastern Himalaya. It grows on open grassy slopes, forest clearings, banks and stony alpine pastures in the temperate to subalpine zone. The cited collection from Koktrok in the Helambu region of Nepal at 3000 m in May places its flowering in the late-spring period on warm-temperate mountain grassland before the onset of the summer monsoon.
It is a perennial herb with slender, ascending to trailing stems arising from a woody rootstock, the herbage thinly clothed in appressed medifixed (dolabriform) hairs typical of the genus. The leaves are imparipinnate with several pairs of small elliptic to obovate leaflets. The flowers are pea-shaped (papilionaceous), borne in axillary racemes on long peduncles, the corolla purplish to violet-blue with a notched standard, oblong wings and a blunt keel, subtended by a campanulate, hairy calyx with short teeth. The fruit is a small, membranous to leathery legume, somewhat inflated and stipitate, dehiscing to release several reniform seeds.
Phyllolobium was segregated from the vast genus Astragalus by Zhang and Podlech on the basis of molecular and morphological evidence, comprising a distinctive Asian clade of milkvetches. P. donianum, transferred from Astragalus donianus DC., exemplifies this realignment. Like other milkvetches it is nitrogen-fixing through rhizobial symbiosis and bee-pollinated; it is widespread and not of conservation concern.
Author: (DC.) M.L.Zhang & Podlech · Sources: POWO (Kew), GBIF, Flora of China, Annotated Checklist of the Flowering Plants of Nepal, Flora of Bhutan, Zhang & Podlech monograph of Phyllolobium