Herbs, annual, 3-3.5 m tall. Stems green or sometimes brown, smooth, with inconspicuous light greenish stripes, slightly glaucous, basally with many adventitious roots; young branches sparsely appressed villous, glabrescent, with white mucilage when broken. Stipules lanceolate, caducous. Leaves 40-60(-80)-foliolate; rachis 15-25 cm, sparsely appressed villous when young, glabrescent, adaxially grooved; petiolules ca. 1 mm, with sparsely appressed trichomes; stipels subulate, subequal to petiolules or shorter, persistent; leaflet blades opposite or subopposite, linear-oblong, 8-20(-40) × 2.5-4(-7) mm, smaller at both ends of rachis than in middle, both surfaces with appressed purplish glands but abaxially denser, abaxially sparsely appressed villous when young but glabrescent, adaxially glabrous, both ends asymmetric, base rounded, apex blunt to truncate and mucronate. Racemes 3-10 cm, 2-6-flowered, lax; peduncle slender, pendulous, sparsely appressed villous; bract linear-lanceolate, caducous. Pedicel slender, pendulous, sparsely appressed villous; bracteoles 2, caducous. Calyx obliquely campanulate, 3-4 mm, glabrous; teeth triangular, with 1-3 appendages between each, inner margin white slender pilose, apex acute. Corolla yellow; standard lamina transversely ovate to suborbicular, 9-10 mm, with a ca. 2 mm claw, base subrounded and with a small pyriform callus, apex retuse to rounded; wings obovate-oblong, ± as long as standard, ca. 3.5 mm wide, with transverse corrugation, base shortly auriculate, middle with dark grayish brown spots; keel broadly triangular-ovate, shorter than wings, as long as wide, with a ca. 4.5 mm claw, apex obtuse. Anthers ovate to oblong. Pistil glabrous; stigma capitate. Legume long terete, slightly curved, 12-22 cm × 2.5-3.5 mm, dehiscent, outside with dark brown stripes, trabeculate between seeds, carpopodium ca. 5 mm, apex acute and with a 5-7(-10) mm beak. Seeds 20-35 per legume, greenish brown, terete, ca. 4 × 2-3 mm, glossy; hilum rounded, slightly oblique to one end. Fl. and fr. Jul-Dec. 2n = 24.