Derris Lour.

         Lianas. Twigs usually lenticellate. Leaves imparipinnate; stipules present, persistent or caducous; stipellae absent or present, persistent. Leaflets generally 3–9, rarely up to 15 per leaf, opposite, entire, variable in shape and size. Inflorescences axillary pseudoracemes, often combined with terminal or axillary pseudopanicles, rarely true panicles, sometimes an intermediate form present: a panicle in the lower part and a pseudoraceme in the upper part, or, a pseudoraceme in the lower part and flowers solitary in the upper part. Flowers usually 2–5 or occasionally up to 7, scattered throughout or on the top of the knob-like, club-shaped to long and slender brachyblasts. Bracts subtending brachyblasts and flowers persistent or caducous, shorter than the corresponding flower buds; bracteoles present, usually at the apex of the pedicel or at the base of the calyx. Calyx cup-shaped, often maroonish or reddish, bilabiate, upper lip 2-lobed, often indistinctly so; lower lip 3-lobed. Corolla generally whitish or pinkish; standard reflexed at base, without or with distinct basal callosities; wings approximately as long as keel petals, in some species curved backward towards the calyx, wings and keel petals adherent by lateral pockets or hooked together by auricles or twisted claws (or any combination). Stamens 10, monadelphous, with basal fenestrae; anthers all equal, fertile, glabrous or hairy. Disc generally inconspicuous or annular. Ovary with 2–5 (rarely up to 7) ovules. Pods indehiscent, thin and stiff, with a wing along both sutures or along the upper suture only, rarely wingless. Seed chambers absent but sometimes seeds surrounded by a thickening of the pod’s vascular bundles. Seeds bean-shaped, 1 or 2(–3) to rarely more per pod; hilum usually central.