Description from Flora of China
Annual herbs, erect, twining, or creeping, 20-60 cm tall. Stems hispid with brown spreading hairs. Stipules peltate, ovate, 0.8-1.2 cm, ciliate; petiole 5-21 cm; leaflets ovate, 5-16 × 3-12 cm, lateral ones ± oblique, ± sparsely pilose on both surfaces, sometimes 3-veined from base, base broadly cuneate or rounded, apex acuminate or acute. Racemes axillary, 4- to several flowered (up to 25). Bracteoles linear-lanceolate or oblong, striate. Calyx tube 3-4 mm, glabrous; lobes narrowly deltoid, 1.5-4 mm, upper 2 connate into a 2-fid lip. Standard yellow-green outside, sometimes pink inside, suboblate, ca. 1.2 × 1.6 cm, apex emarginate; wings yellow, ovate; keel falcate and incurved through 180°, green tinged with pink. Legumes linear-terete, 4-9 × ca. 0.6 cm, shortly hispid with pale brown hairs. Seeds 8-14, greenish or yellow-brown, shortly cylindric, 2.5-4 × 2.5-3 mm; hilum white. Fl. May-Jun, fr. Jun-Sep.
The seeds are edible and are used medicinally.
Two varieties occur in China. In addition, Vigna radiata var. glabra (Roxburgh) Verdcourt (Kew Bull. 24: 559. 1970; Phaseolus glaber Roxburgh, Fl. Ind., ed. 1832, 3: 291. 1832) was said to occur in China in Fl. Cambodge, Laos & Vietnam (17: 198. 1979). This variety has almost glabrous stems, leaves, and legumes, but no specimens from China have been seen.
Open wastelands, roadsides, thicket margins, also cultivated; ca. 500 m. Taiwan; cultivated throughout China [Cambodia, India, Indonesia, Laos, Sri Lanka, Thailand, Vietnam; Africa; widely cultivated in tropical and subtropical regions].