Annual herbs, (5-)10-20(-50) cm. Stems prostrate or ascending, quadrangular, branched at base, sparsely hairy. Stipules ovate, incised or lacerate; leaflets obovate or obcordate, (2-)4-8(-12) × (2-)5-9(-13) mm, papery, sparsely hairy abaxially, glabrous adaxially, base broadly cuneate, margin only obscurely serrate apically, apex truncate or emarginate. Flowers 1 or 2 in axillary umbel; peduncles shorter than petiole, bracts ca. 1.5 mm; pedicels less than 1 mm. Corolla yellow, 3-4 mm; standard broadly orbicular. Ovary linear. Legume usually only 1 per umbel, scarlet to dark brown, discoid, 3-4 mm, loosely coiled in 2-4(or 5) spirals, coil edge wide, deeply grooved, spines 10 in each row. Seed brown, reniform, 2-2.8 × 1-1.3 mm. Fl. Mar-Apr, fr. May-Jul.
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