Derris ferruginea (Roxb.) Benth.

         Lianas, basal diameter 10–15 cm. Bark smooth, greenish and aging to more pale grayish-brown. Twigs densely covered with golden-brown hairs. Stipules ovate to triangular, 3–4 by 1–4 mm, outside velvety, inside glabrous. Leaves with 7–9 leaflets, occasionally reddish or brownish when young; petiole 3.5–6.5 cm long, slightly grooved above, sericeous; rachis 5–7 cm long, slightly grooved above, sericeous; pulvinus 5–10 mm long. Stipellae absent. Leaflets subcoriaceous; terminal one elliptic or obovate, 6.5–12 by 3–5 cm, length/width ratio 2.1–3, base cuneate, apex acuminate or obtuse to rounded, acumen up to 15 mm long, rounded, upper surface glabrous but hairy along midrib and lateral main veins, lower surface slightly strigose to velvety, midrib and veins flat or slightly raised above, veins 7–9 per side, 5–10 mm apart, not reaching the margin but curving towards the apex, sometimes anastomosing near the margin, venation usually reticulate but sometimes slightly scalariform near midrib; lateral ones (narrowly) elliptic, ovate or obovate, 4–15 by 2–4.5 cm, length/width ratio 2–3.3, base cuneate, apex acuminate or obtuse to rounded, acumen up to 1.5 cm long, rounded; pulvinus 5–6 mm long, sericeous. Inflorescences axillary or terminal Pseudoracemes/pseudopanicles, 9–23.5 cm long, peduncle 1–1.5 cm long, sericeous, branches 6–11 cm long. Bracts subtending brachyblasts ovate-triangular, 1.5–2.5 by 0.8–1.2 mm, outside sericeous, inside glabrous; bracts subtending flowers ovate, 1–1.8 by 0.5–0.8 mm, outside velvety, inside glabrous. Brachyblasts knob-like to cylindrical, 1–3.5 mm long, with 3–7 flowers. Pedicels 6–7 mm long, sericeous. Bracteoles in the middle or in the upper part of pedicels nearly at the top, sometimes caducous, ovate or narrowly ovate, 0.8–1.2 by 0.2–0.5 mm, outside velvety, inside glabrous. Calyx cup-shaped, dull maroonish, 2–2.5 mm high, outside thinly sericeous, inside glabrous or sericeous along the margin, tube ca. 2 mm high; upper lip with 2 short lobes, 0.1–0.2 by 2–2.5 mm; lateral lobes short triangular, 0.7–1 by 2–2.5 mm, apex obtuse; lower lobe shortly triangular, 0.6–0.8 by 2–2.5 mm, apex obtuse. Corolla white. Standard: claw 2.7–2.8 mm long; blade orbicular, ca. 9 by 7 mm, apex emarginate, without auricle or basal callosities, outside thinly sericeous, especially at the apex, inside glabrous. Wings: claw 3–3.2 mm long; blade elliptic, 6–7 by 0.7–1 mm, apex rounded, outside hairy at the apex, inside glabrous, upper auricle ca. 1 mm long. Keel petals: claw ca. 2.8 mm long; blade boat-shaped, ca. 7.5 by 2.5 mm, apex rounded, outside hairy at the apex, inside glabrous, lateral pocket small or indistinct, 0.5–1 mm long, auricle ca. 1 mm long. Stamens monadelphous, with basal fenestrae, 9–10 mm long, free part of filaments 3–4 mm long, glabrous; anthers ca. 0.5 by 0.4 mm, glabrous. Disc indistinct. Ovary sericeous to velvety, 7–7.5 mm long, stipe sericeous, 1–1.2 mm long; ovules 3–5; style 5–6 mm long, glabrous but slightly sericeous at base. Pods elliptic to strap-like, 7.8–9.5 by 3–3.5 cm, flat, thin, velvety, leathery with a wing along both sutures, flat, upper wing 4–10 mm wide, lower wing 4–7 mm wide; seed chamber hardly visible. Seeds 1 or 2 per pod, bean-shaped, flat, 18–20 by 12–15 mm; hilum central.