乳豆 ru dou

Glycine tenuiflora Klein ex Willdenow, Sp. Pl. 3: 1059. 1802; Galactia elliptifoliola Merrill; G. formosana Matsumura; G. lanceolata Hayata.

Herbs, perennial, climbing. Stems puberulent to densely villous with grayish white or grayish yellow hairs. Petiolules ca. 2 mm; stipels subulate, 1-1.5 mm; leaflets elliptic, oblong, or lanceolate, 2-7 × 1.3-4 cm, papery, sparsely puberulent to densely villous abaxially, sparsely puberulent to subglabrous adaxially, lateral veins 4-8 pairs, slender, slightly raised on both surfaces, veinlets reticulate, conspicuous on both surfaces, base and apex rounded, apex sometimes emarginate, mucronate. Ra­cemes axillary; rachis slender, 2-20 cm. Flowers solitary or often 2-4 clustered at nodes of rachis. Calyx ca. 7 mm, sub­glabrous to pubescent, tube ca. 3 mm, lobes narrowly lanceo­late, apex acuminate. Corolla light blue or pink; standard obo­vate, ca. 10.5 × 7 mm, base attenuate, with 2 small auricles, apex rounded; wings oblong, ca. 9 × 2 mm, base with a pointed auricle; keel as long as or longer than wings, slightly curved on back, base with a small auricle. Legumes linear-oblong, 2-6.5 × 0.6-0.7 cm, puberulent to villous at first, glabrescent. Seeds brown, reniform, slightly compressed, 2-3.5 × 3-5 mm, smooth. Fl. and fr. Jul-Dec.

Forests, scrub, hillsides. Guangdong, Guangxi, Hainan, Hunan, Jiangxi, Taiwan, Yunnan [India, Malaysia, Philippines, Sri Lanka, Thai­land, Vietnam; Africa].