Description from Flora of China
Sophora platycarpa Maximowicz, Bull. Acad. Imp. Sci. Saint-Pétersbourg 18: 398. 1873; Cladrastis yungchunii Xiang W. Li & G. S. Fan; Platyosprion platycarpum Maximowicz.
Trees, to 30 m tall, 80-120 cm d.b.h.; bark dark gray, many lenticellate. Leaves imparipinnately compound; leaflets (7-)13(-15); stipels 1 on either side of pulvinus, unbranched, subulate, to 2 mm, glabrous; petiolule 3-5 mm, densely gray-brown hairy; blades long elliptic or ovate-oblong, smaller toward base, 2-10 × 1-3.5 cm, pilose near midrib or glabrous abaxially, glabrous adaxially, veins obviously raised abaxially with obvious veinlets, base obtuse or broadly cuneate, apex acuminate. Panicle 9-30 cm, to 15 cm in diam. Pedicel slender, 7-11 mm. Calyx campanulate, densely white-yellow sericeous, triangular toothed. Corolla white, with yellow spot in throat; standard oblong, 5.3-8.2 × 5.3-8.6 mm, rounded or retuse at apex, claw 1.2-4.8 mm; wings lanceolate-ovate, 5.9-9.3 × 3.2-5.4 mm, slightly auriculate, claw 2.9-5.1 mm; keels lanceolate, 6.4-9.9 × 3.5-5.9 mm, base auriculate. Ovary linear, yellow-white pubescent, 5-7-ovuled; style slightly curved. Legumes long elliptic or oblong, 5-8 × 1.5-2 cm, winged on both sides, indehiscent. Seeds 1-3, dark brown or black, oblong, ca. 8 mm. Fl. Apr-Jun, fr. Jul-Oct.
Forests in valleys and on slopes; below 1000 m. Guangdong, Guangxi, Guizhou, Hunan, Jiangsu, Yunnan, Zhejiang [Japan].