Herbs. Stems twining, slender, sparsely pubescent. Leaves pinnately 3-foliolate; stipules small, ovate, membranous, deciduous; petiole 2.5-7 cm, pubescent; stipels bristlelike; petiolules short; terminal leaflet ovate or broadly elliptic, 4-8 × 2-5.5 cm, almost membranous, both surfaces sparsely villous, abaxial surface with sessile glands, basal veins 3, lateral veins ca. 3 pairs, base rounded, apex acuminate or long acuminate; lateral leaflets obliquely ovate, smaller. Raceme axillary, slender, usually ± as long as petiole, pubescent; peduncles slender, 5-10 mm. Flowers clustered, ca. 1 cm. Calyx campanulate, 3-5 mm; lobes triangular, much shorter than tube, lower one longer, sparsely pubescent. Corolla yellow, longer than calyx, petals subequal; standard subcircular, base with inflexed auricles; keel apex with long beak. Ovary linear, 2-ovuled; style long and curved. Legume red, oblong, compressed, 1.2-1.5 × ca. 0.9 cm, apex with small beak. Seeds 1 or 2, usually black, reniform-orbicular, ca. 5 mm in diam. Fl. and fr. Jul-Oct.
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