直生刀豆 zhi sheng dao dou

Dolichos ensiformis Linnaeus, Sp. Pl. 2: 725. 1753.

Herbs, annual, subshrubby, 0.6-1(-2) m, wholly pubescent or glabrescent. Stipules small, deciduous; leaflets thin, ovate or elliptic, 8-18 × 5-8 cm, base cuneate or rounded, apex acute. Racemes solitary, 15-25(-40) cm including peduncle. Flowers 1-5 at nodes of rachis. Calyx ca. 1.5 cm, upper lip truncate, as long as calyx tube, lower lip with deltoid lobes. Corolla pur­plish or white and purple; standard ca. 2.2 cm in diam., base with 2 semiorbicular, reflexed auricles, claw flat and broad, ca. 5 mm; wings obovate-oblong; keel auriculate and clawed. Leg­umes thickly leathery, ligulate, 20-30 × 2.5-4 cm, each valve with extra rib ca. 5 mm from sutural rib. Seeds white, elliptic, ca. 3 × 2 cm; hilum not more than 1.5 cm. Fl. May-Jul, fr. Oct.

Cultivated. Guangdong, Hainan, Taiwan [native to Central Ameri­ca and West Indies; widely cultivated in tropical and subtropical re­gions].

This species is used as a green manure and forage.