Description from Flora of China
Phaseolus lathyroides Linnaeus, Sp. Pl., ed. 2, 2: 1018. 1763.
Annual or biennial herbs, erect, 0.6-1.5 m tall, sometimes prostrate or twining. Stems densely pubescent. Stipules lanceolate, 5-10 mm; petiole 0.5-5 cm; leaflets narrowly elliptic to ovate-lanceolate, 3-8 × 1-3.5 cm, abaxially densely pubescent or sparsely pilose, adaxially glabrous, sometimes slightly lobed, base cuneate, apex acute. Inflorescences with peduncles 15-40 cm, flowers paired in upper part of rachis. Calyx tubular-campanulate; teeth shortly triangular. Corolla purple-red; standard suborbicular, ca. 1.5 cm, with pale claw. Legumes linear, 5.5-10 cm × 2-3 mm, densely pubescent, 18-30-seeded. Seeds brown or with brown and black markings, obliquely oblong, ca. 3 mm.
This species is used as a cover crop.
Cultivated. Fujian, Guangdong, Taiwan (also naturalized) [native to tropical America; widely cultivated and naturalized in the tropics].