Description from Flora of China
Medicago polymorpha Linnaeus var. minima Linnaeus, Sp. Pl. 2: 780. 1753.
Annual herbs, 5-30 cm, spreading hairy, sometimes with glandular hairs. Stems diffuse, prostrate or ascending, branched at base. Stipules ovate, base rounded, margin entire or obscurely shallowly serrate, apex acute; petioles slender, 5-10(-20) mm; leaflets obovate, 5-8(-12) × 3-7 mm, papery, villous on both surfaces, base cuneate, margin serrulate in apical 1/3, apex rounded or retuse, apiculate. Flowers 2-10 in capitate racemes; peduncles slender and straight; pedicels short or sessile. Corolla pale yellow, 3-4 mm; standard broadly ovate, longer than wings and keel. Legume globose, 2.5-4.5 mm, tightly coiled in 3-5 spirals; spines straight with hooked tip, equal to radius of legume. Seed long reniform, brown, 1.5-2 mm, smooth. Fl. Mar-Apr, fr. Apr-May.
Sandy slopes, waste fields, stream banks. Anhui, Gansu, Hebei, Henan, Hubei, Jiangsu, Liaoning, Shaanxi, Shandong, Shanxi, Sichuan, Zhejiang [Africa, Asia, Europe].