Derris elegans Graham ex Benth.

         Lianas, up to 25 m long. Outer bark green, inner bark yellow. Twigs 3–12 mm diam., hirsute or thinly strigose to glabrous. Stipules narrowly triangular, 2–5 by 2–5 mm, caducous, outside strigose or hirsute to glabrous, inside glabrous. Leaves with 3 or 5 leaflets; petiole 1–16 cm long, striate, strigose, or hirsute to glabrous; rachis 1–11 cm long, striate, strigose or hirsute to glabrous; pulvinus 4–10 mm long, (thinly) hirsute. Stipellae acicular, 1.5–5 mm long. Leaflets chartaceous; terminal one elliptic to obovate, 6.5–20.5 by 2.5–9 cm, length/width ratio 1.6–2.8, base rounded to cuneate or subpeltate, rarely cuneate, apex obtuse to rounded or shortly and broadly acuminate, acumen 2–3 mm long, rounded or emarginate, upper surface glabrous or more or less hirsute on midrib and nerves in lower part, lower surface hirsute to velvety, in older leaflets often much less hairy, then mostly along midrib and nerves, midrib and nerves raised above, nerves 6–10 per side, 6–29 mm apart, not reaching the margin but curving towards the apex, sometimes anastomosing near the margin, venation reticulate; lateral ones mostly like terminal one, (broadly) ovate to elliptic, 4.5–16.5 by 3–7.5 cm, length/width ratio 1.5–2.9; pulvinus 2–9 mm long, hirsute to glabrous. Inflorescences axillary and ramiflorous pseudoracemes, sometimes several together forming pseudopanicles, 1.5–23 cm long; peduncle 0–20 cm long, thinly hirsute, sometimes strigose. Bracts subtending brachyblasts narrowly triangular or narrowly elliptic to ovate, 1–5.5 by 0.3–0.8 mm, outside sericeous, inside glabrous; bracts subtending flowers (narrowly) ovate to triangular to elliptic or linear, 0.5–4 by 0.2–6 mm, outside sericeous, inside glabrous. Brachyblasts knob-like, shortly cylindrical, up to 2.5 mm long, with 2 or 3 flowers. Pedicels 2.5–9 mm long, hirsute or strigose. Bracteoles in the upper part of the pedicels, often at different heights, narrowly ovate or narrowly triangular to elliptic or linear, 0.5–1.7 by 0.2–0.5 mm, outside sericeous, inside glabrous. Calyx 2.5–4.5 mm high, brownish to purple or red, rarely green, outside sericeous, inside glabrous, tube 2–3.5 mm high; upper lip 0.5–1 by 1.5–4.5 mm, shallowly notched; lateral lobes triangular or semicircular, 0.5–1 by 1.5–3 mm; lower lobe triangular, 0.5–1.5 by 1.5–2.5 mm. Corolla pale pink to white. Standard: claw 1.5–3 mm long; blade orbicular, rarely obovate, 8–9.5 x 9.5–10.5 mm, apex emarginate, without basal callosities, outside sericeous or at least with some hairs at the apex, inside glabrous. Wings: claw 2.5–4 mm long; blade elliptic, 7–9 by 3–3.5 mm, apex rounded, upper auricle 0.5–1 mm long, lower auricle indistinct, lateral pocket indistinct, outside with some hairs at the ventral side at the apex, inside glabrous. Keel petals: claw 2–4 mm long; blade more or less boat-shaped, 7–8.5 by 2.5–4 mm, apex rounded, auricle 0.2–1 mm long, lateral pocket 1–2.5 mm long, outside sericeous at the upper part, at least at the ventral side, inside glabrous, rarely with some hairs at the apex. Stamens monadelphous, with basal fenestrae, 8–12 mm long, free part 1–4 mm long, alternately longer and shorter, glabrous; anthers 0.3–0.6 by 0.2–0.4 mm, glabrous. Disc hardly visible. Ovary 3.5–6 mm long, sericeous; stipe 0.5–1 mm long, sericeous; ovules 2–5; style 4–8 mm long, sericeous at base. Pods more or less oblong to orbicular, 3–6 by 1.5–3 cm, only a single wing along the upper suture, sometimes hardly visible, 0–3 mm wide, (thinly) hirsute; seed chamber absent. Seeds discoid or bean-shaped, compressed, 9–14 by 7–13 by 1–4 mm; hilum central, 1–2 mm long.