Chi Xiao Dou

Vigna umbellata, the rice bean, is an annual to short-lived perennial twining legume in the family Fabaceae, native to tropical and subtropical Asia and cultivated as a minor pulse crop and green manure across India, China, southeast Asia, and parts of Africa. The plant produces slender, soft-hairy, twining or trailing stems 1-3 m long from a slender taproot. The alternate leaves are pinnately trifoliolate with ovate to ovate-rhombic leaflets 4-10 cm long, the terminal one symmetrical and the lateral ones often somewhat lobed at the base, all sparsely hairy. Bright yellow papilionaceous flowers about 1.5 cm long are borne in short, dense, axillary racemes on long peduncles, the keel petals strongly twisted. The fruit is a slender, cylindrical, slightly curved pod 6-12 cm long that ripens from green to brown and contains 6-12 small, oblong, somewhat compressed seeds, commonly red, but also yellow, brown, or mottled depending on the cultivar.