Small or medium-sized, deciduous, tree with sparse crown, branching high above the ground, bark gray, white or dull black; leaves opposite, bipinnately compound, rachis grooved, pinnae about 20 pairs, leaflets 12-26 pairs, elliptic-oblong or rhomboid, terminal ones linear-lanceolate, cuspidate; flowers in large terminal panicles, blue to violet in color; calyx shortly 5-toothed; corolla infundibuliform, densely hairy, subequally bilipped, lobes more or less equal, tube curved below, hairy at throat; stamens-4, didymous, included, staminode with long filament; ovary 2-celled, oblong, style slender, stigma oblong; capsules ovoid, orbicular, compressed, woody, straight with pointed ends, containing numerous, flattened, papery, winged seeds.