Description from Flora of China
Dolichos minimus Linnaeus, Sp. Pl. 2: 726. 1753; Dolicholus flavus Medikus, nom. illeg. superfl.
Herbs, annual. Stems twining, slender, sparsely pubescent. Leaves pinnately 3-foliolate; stipules small, lanceolate, usually 1-2 mm; petiole 1-4 cm, glabrous or sparsely pubescent; stipels extremely small; petiolules extremely short; leaflets ± membranous; terminal leaflet rhomboid-circular, 1.5-3 × 1.5-3 cm, sometimes wider than long, glabrous or sparsely villous, abaxially densely glandular, basal veins 3, apex obtuse or rounded, rarely shortly acute; lateral leaflets subequal to terminal leaflet or shorter, obliquely circular. Raceme 5-11 cm, axis slender, sparsely pubescent; bracts small, lanceolate, deciduous. Flowers 6-8 mm, slightly curved; pedicel extremely short. Calyx ca. 5 mm, sparsely pubescent; lobes lanceolate, slightly shorter than tube, lower one longer. Corolla yellow, longer than calyx, petals subequal; standard obovate-circular, base with 2 acute auricles; wings obovate-elliptic, auriculate; keels slightly curved, apex obtuse. Legume oblanceolate to ellipsoid, 1-2 × 0.4-0.5 cm, pubescent, 1- or 2-seeded. Fl. May-Oct, fr. Sep-Nov. 2n = 22.
This is a very variable species that has defied attempts to divide it into more homogeneous taxa.
Forests; 900-2500 m. Sichuan, Taiwan, Yunnan [Afghanistan, Bhutan, India, Indonesia, Japan (Ryukyu Islands), Malaysia, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, Vietnam; thought to be native in Africa and Asia, now pantropical].