形态特征：Perennial climbing herbs. Stems quadrangular, densely hirsute with spreading yellowish hairs up to 3 mm. Branches trailing along wet ditches by virtue of plenty of adventitious roots rising from lower nodes. Leaves pinnately trifoliolate; stipules basifixed, long ovate, ca. 6 mm, densely hirsute with finer hairs; petioles triangulate in cross section, densely hirsute along ridges; leaflets rhomboid-ovate, 7–15 × 3.5–8 cm, with lateral ones oblique and smaller, acuminate at apex, broadly cuneate at base, adaxial surface sparsely covered with appressed grey hairs, densely hirsute with spreading hairs along margins, abaxial surface hairy much denser, secondary veins 4–5 pairs; petiolules densely hirsute; stipels setaceous, ca. 4 mm, hirsute. Pseudoraceme axillary, 4–12 cm, 2–3 flowers per node, sometimes cauliflorous; rachis angulate. Bracts setaceous, hirsute, ca. 4 mm. Flower ca. 6 mm with a 1 mm pedicel. Calyx 4-lobed, with the upper two teeth almost connate, ca. 2.5 mm, pubescent; Corolla white. Standard obovate, ca. 3 mm, blunt auriculate, with a purple patch in the center, attenuate to a short stalk; wings oblanceolate, ca. 6 mm, auriculate on both sides; keels oblong, ca. 4.5 mm. Stamens monadelphous. Pods linear, 5–8 × 0.5 cm, septate between the seeds. Seed ovoid to quadrate with rounded edges, compressed.
