Robust vines clambering on the ground and on shrubs, occasionally high climbing; stems terete, branching, puberulent with appressed short hairs. Leaves pinnate trifoliolate, the leaflets often large and somewhat felty, broadly ovate, often 3-lobate, apically short acuminate, the sinuses rounded to obtuse, mucron- ulate, basally rounded, truncate or subcordate, 3 nerved from the base and pin- nate veined above, discolorous, appressed pubescent on both sides, often with coarse hairs, often ca. 15 cm long and 15 cm wide, the lateral leaflets strongly oblique; petiolules 4-7 mm long, often stout, tomentose; rachis 2-5 cm long; petioles shorter than the terminal leaflet; stipels linear, pubescent, 4-7 mm long; stipules oblong or ovate, puberulent, 4-8 mm long and produced 3-5 mm below the point of insertion, the insertion point ovate. Inflorescences often few, to 30 cm long, the peduncle stout, pubescent, sometimes with 1 or 2 empty stipule-like bracts along its length; rachis slightly thinner, often more than twice as long as the peduncle; pedicels 3-6 mm long, pubescent, inserted mostly in 3's at the nodes; bracts ovate and stipule-like, caducous; bracteoles ovate, ciliate and pu- bescent, 3-5 mm long. Flowers pink or violet, ca. 2 cm long, the calyx campan- ulate, puberulent outside, the cup ca. 5 mm long, the lobes obtuse, unequal, the upper pair mostly or completely fused into a lip, the lowest tooth narrow and usually longest; corolla with the standard broad, emarginate, glabrous, slightly shorter than the wings and the keel, with 2 minute basal auricles, the wings oblong, medially coherent; stamens 10, the vexillary stamen free at the base, perhaps fused to the filament column part way up, the anthers all alike; ovary pubescent, the style and the stigma glabrous, the style bent abruptly upwards. Legume oblong, 4-6 cm long, 4-7 mm wide, long beaked, flat and compressed slightly between the seeds, drying dark, copiously pilose with long, 2-3 mm, yellowish hairs.
"Stems 10–30 m, the younger parts hairy; lfls broadly ovate to subrotund, 10–15 cm, often 2–3-lobed, hairy beneath; infls 1–2 dm, the axis and pedicels densely sericeous; fls 2–2.5 cm; lowest cal-lobe 8–12 mm; standard yellow at base; fr 4–5 cm; 2n=22, 24. Native of Japan, China, and Korea, cult. for forage and erosion-control in se. U.S., escaped and extending n. into the s. part of our range, sometimes even to Mass., N.Y., and O. Late summer. (P. thunbergiana)"