紫花大翼豆 zi hua da yi dou

Phaseolus atropurpureus Candolle, Prodr. 2: 395. 1825.

Perennial prostrate herbs, sometimes rooting at nodes. Stems pubescent or tomentose. Stipules ovate, 4-5 mm, pilose; petiole 0.5-5 cm; leaflets ovate to rhombic, 1.5-7 × 1.3-5 cm, sometimes lobed, lateral ones oblique, lobed on outer side, abaxially silvery tomentose, adaxially pubescent, base rounded, apex obtuse or acute. Inflorescences with peduncle 10-25 cm and rachis 1-8 cm. Calyx campanulate, ca. 6 mm, white pilose. Corolla deeply blackish purple; standard 1.5-2 cm, with long claw. Legumes linear, 5-9 cm × ca. 4 mm, apex rostrate, 12-15-seeded. Seeds marbled with brown and black striae, oblong-elliptic, ca. 4 mm.

Cultivated. Guangdong, Taiwan (also naturalized) [native to tropi­cal America; widely cultivated and naturalized in the tropics].

This species is used for forage.