Herbs, perennial, 50-150 cm tall. Stems glabrescent. Leaves 5-7-foliolate; petiole ca. 6 cm, pubescent; leaflet blade lanceolate, oblong, or ovate-elliptic, 6-15 × 3-5 cm, both surfaces sparsely pubescent, base cuneate or obtuse, apex acuminate. Racemes simple or shortly branched at lowermost part, to 40 cm, uncinate pubescent and yellow pubescent, laxly flowered. Pedicel 4-6 mm, elongated to 6-11 mm at fruiting. Calyx 2.5-3 mm; upper lobes distinctly 2-toothed at apex. Corolla purplish red, ca. 7 mm; standard broadly elliptic; wings and keel narrowly elliptic, base shortly clawed. Stamens monadelphous. Ovary linear, stipitate. Legume flat, uncinate pubescent, mostly 2-jointed, rarely 1-or 3-jointed; articles obliquely triangular, 1-1.5 cm × 5-7 mm. Seeds ca. 9 × 5 mm. Fl. Aug-Sep, fr. Sep-Oct. 2n = 22.
Woods and thickets in C. and S. Japan. Forests on mountain slopes, streamsides, thickets and rocky places at elevations of 100-1700 metres. Oak groves and shrubby thickets, gravelly soils of mountain slopes.
Can be grown by cuttings or seedlings. Seeds needs scarification and soaking.
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