菜豆 cai dou

Annual herbs, twining or suberect. Stems pubescent or glabrescent when old. Stipules lanceolate, ca. 4 mm; leaflets broadly ovate or obovate-rhombic, lateral ones oblique, 4-16 × 2.5-11 cm, pubescent, base rounded or broadly cuneate, margin entire, apex acuminate. Racemes shorter than leaves, usually several flowered at top of rachis. Bracteoles ovate, usually as long as calyx or slightly longer, persistent. Calyx cup-shaped, 3-4 mm, upper lip emarginate. Corolla white, yellow, violet, or red; standard 9-12 mm wide; wings obovate; keel ca. 1 cm, apex spirally twisted. Ovary pubescent. Legumes linear-oblong, 10-15 × 1-1.5 cm, slightly curved and turgid, glabrous, beaked. Seeds 4-10, white, brown, blue, or variegated, oblong or ensi­form, 0.9-2 × 0.3-1.2 cm. Fl. Apr-Jul.

Cultivated. Throughout China [native to tropical America; widely cultivated everywhere].

This species is used as a vegetable.

Phaseolus vulgaris var. humilis Alefeld is a variety frequently cultivated in Guangdong.