Description from Flora of China
Phaseolus fuscus Wallich, Pl. Asiat. Rar. 1: 6. 1830; Atylosia crinita Dunn.
Herbs, annual. Stems twining, up to 3 mm thick, densely pubescent. Leaves pinnately 3-foliolate; stipules absent or deciduous; petiole 3-6.5 cm, densely pubescent; petiolules 1-2 cm; leaflets papery, subequal; terminal leaflet ovate, ovate-lanceolate, or lanceolate, 5-9.5 × 2.5-4 cm, abaxial surface densely pubescent and with reddish glands, adaxial surface glabrous or sparsely pubescent, basal veins 3, lateral veins 3 or 4 pairs, flat or slightly convex, base rounded or subcuneate, apex acute to acuminate; lateral leaflets similar but smaller. Raceme axillary, slightly robust, 4-15 cm, glabrous or sparsely pubescent, usually several or more flowered; bracts absent. Flower ca. 1.5 cm; pedicel 2-4 mm. Calyx campanulate, 4-7 mm, hirsute, glabrescent, and with brown glands, 4-lobed; lobes triangular or almost triangular, shorter than tube, lowest longer, linear-lanceolate. Corolla purple, ca. 1.3 cm; standard transversely elliptic, base auriculate on both sides; wings oblong, auriculate on one side; keels inflexed to almost right angle. Ovary sessile, densely golden hirsute. Legume black-brown, linear-oblong, 4-6 × 0.4-0.7 cm, hirsute; stipe absent. Seeds 5-7, brown, semiorbicular, ca. 4 × 4 mm. Fl. Jul-Sep, fr. Oct-Dec.
Slopes, open grasslands; 200-1200 m. Guangdong, Guangxi, Hainan, Yunnan [India, Laos, Malaysia, Myanmar, Thailand, Vietnam].