7. Medicago sativa Linnaeus, Sp. Pl. 2: 778. 1753.
紫苜蓿 zi mu xu
Medicago afghanica Vassilczenko; M. alaschanica Vassilczenko; M. asiatica Sinskaya subsp. sinensis Sinskaya; M. beipinensis Vassilczenko; M. pekinensis Vassilczenko; M. rivularis Vassilczenko; M. roborovskii Vassilczenko; M. sativa var. tibetana Alefeld; M. tibetana (Alefeld) Vassilczenko.
Perennial herbs, 30-100 cm. Stems erect, ascending, rarely prostrate, quadrangular, glabrous or puberulent, much branched. Stipules ovate-lanceolate, base entire or with 1 or 2 denticles, apex acute; leaflets long ovate, obovate, to linear-ovate, (5-)10-25(-40) × 3-10 mm, papery, appressed pubescent abaxially, glabrous adaxially, lateral veins 8-10 pairs, base tapering, margin serrulate in upper 1/3, apex rounded, mucronate with a denticle from midrib. Heads or racemes with 5-30 flowers, 1-2.5 cm; peduncles straight, longer than leaves; bracts equal to pedicels, ca. 2 mm. Corolla variable in color, white, deep blue, to dark purple; standard oblong, retuse. Ovary linear; ovules numerous. Legume tightly coiled in 2-4(-6) spirals, 5-9 mm in diam., center solid or nearly so, brown when ripe, veins thin and inconspicuous. Seeds 10-20, yellow or brown, ovoid, 1-2.5 mm, smooth. Fl. May-Jul, fr. Jun-Oct.
Cultivated throughout China, often escaped to roadsides, fields, grasslands, and stream banks [native to N and SW Asia, probably also S Europe; now cosmopolitan].