豆薯 dou shu

Dolichos erosus Linnaeus, Sp. Pl. 2: 726. 1753; Pachyrhi­zus angulatus Richard ex Candolle, nom. illeg. superfl.

Vines, robust, twining. Root tubers 10-20 cm in diam. Leaflets rhombic or ovate, 4-18 × 4-20 cm, upper margin often somewhat dentate or lobed, lateral ones very oblique, sparsely pubescent abaxially. Racemes axillary, 15-30 cm; flowers 3-5 at thickened nodes. Calyx campanulate, 9-11 mm, adpressed pilose. Corolla purplish or pink; standard suborbicular, 15-20 mm, with yellow-green spot and 2 thickenings near base; wings falcate, auriculate; keel subfalcate, 15-20 mm. Ovary yellowish hirsute; style curved. Legumes 7.5-13 × 1.2-1.5 cm, com­pressed, hirsute. Seeds 8-10, subsquare. Fl. Aug, fr. Nov.

Cultivated. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hu­nan, Sichuan, Taiwan, Yunnan [native to tropical America; widely culti­vated in tropical regions].

This species is used as a vegetable.