Description from Flora of China
Woody climbers, large, sometimes small trees. Bark brown; branches spreading. Leaves 15-20 cm; stipules early caducous, ovate-lanceolate to lanceolate, membranous; leaflets 17-21; petiolules 1.5-2 mm; blades oblong to obovate-oblong, 2.8-3.5 × 1-1.2(-2) cm, lowest sometimes elliptic, 1.2-1.5 × ca. 1 cm, thinly papery, abaxially sparsely appressed puberulent, adaxially glabrous, base broadly cuneate or rounded, apex acute, ultimately rounded or obtuse, sometimes emarginate. Panicles in axils of leaves, which at apex of branchlets rise among clustered, scalelike, early-deciduous bracts; peduncle, rachis, branches, and bracts appressed brown pubescent, lower part of inflorescence with many scattered, ovate, membranous, empty bracts. Bracts of flowers smaller than inflorescence bracts; bracteoles obovate, enclosing ca. 2/3 of calyx. Calyx campanulate, puberulent; teeth ovate, shorter than tube except lowest ca. as long as tube. Corolla pale blue or pale purplish red; petals distinctly clawed; standard orbicular, slightly emarginate; wings with downward auricles on upper side below. Stamens 10, diadelphous (5+5). Ovary glabrous except for pubescent long stipe, 1(or 2)-ovuled; style slender; stigma small. Legume broadly ligulate to ovoid or elliptic, (6.5-)9-11 × 3.2(-4) cm, firmly leathery, glabrous, not veined except sometimes opposite seed where mesocarp is much thickened, base cuneate or rounded, apex obtuse or rounded, 1-seeded, very rarely 2-seeded. Seeds reniform, ca. 15 × 8 mm. Fl. Apr-May, fr. Aug-Jan.
Open forests, ravines to mountain summits; 700-1700 m. Yunnan [Cambodia, NE India, Laos, Malaysia, Myanmar, Thailand, Vietnam].