12. Medicago polymorpha Linnaeus, Sp. Pl. 2: 779. 1753.
南苜蓿 nan mu xu
Annual or biennial herbs, 20-90 cm. Stems prostrate or ascending, branched at base, subquadrangular, glabrescent. Stipules ovate-oblong, 4-7 mm, base auriculate, margin irregularly laciniate or deeply incised, apex acuminate; petioles long and thin, 1-5 cm; leaflets obovate or triangular-obovate, 7-20 × 5-15 mm, papery, sparsely hairy abaxially, glabrous adaxially, base broadly cuneate, margin shallowly serrate in apical 1/3, apex obtuse, truncate, or emarginate, apiculate. Flowers (1 or)2-10 in axillary racemes; peduncles slender, 3-15 mm, usually longer than leaves; pedicel less than 1 mm. Corolla yellow, 3-4 mm; standard obovate, emarginate. Legume ash-green to greenish brown, discoid, 4-6(-10) mm, tightly coiled in 1.5-2.5(-6) spirals, turning clockwise, radial veins connected near edge on coil face, spines or tubercles 15 in each row. Seed brown, reniform, ca. 2.5 × 1.25 mm, smooth. Fl. Mar-May, fr. May-Oct.
Cultivated or escaped to fields, hillsides, and roadsides. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Sichuan, Taiwan, Yunnan, Zhejiang [native at least to N Africa, SW Asia, and S Europe; widely introduced elsewhere].