Derris amoena Benth.

         Lianas. Bark maroonish, lenticellate, glabrous. Twigs 3–5 mm diam., slightly strigose or glabrescent, lenticellate. Stipules triangular, ca. 1.5 by 0.7–1 mm, outside thinly sericeous, inside glabrous. Leaves with 5–9 leaflets, reddish when young; petiole 3.5–6 cm long, slightly grooved and striate, glabrous or with few hairs; rachis 3.5–11 cm long, grooved and striate, glabrescent; pulvinus 5–9 mm long, thinly strigose. Stipellae absent. Leaflets subcoriaceous; terminal one elliptic to obovate, 6–9 by 3–4.5 cm, length/width ratio ca. 2, base cuneate to rounded, apex acuminate, acumen 2–5 mm long, rounded, upper surface glabrous or slightly strigose, especially at the basal part of the midrib, lower surface glabrous or slightly strigose, usually glaucous, midrib flat or slightly raised above, veins flat on both sides, 7–13 per side, 2–10 mm apart, parallel, seemingly ending and anastomosing in the margin, venation reticulate; lateral ones mostly like terminal one, elliptic to obovate, 4.5–8.5 by 2–4 cm, length/width ratio 2.1–2.3; pulvinus 5.5–7 mm long, glabrous. Inflorescences axillary pseudoracemes or pseudopanicles, 7–18 cm long, peduncle 0.5–4.5 cm long, striate, glabrous or sometimes slightly sericeous. Bracts subtending brachyblasts ovate to triangular, ca. 0.8 by 0.6–0.7 mm, outside sericeous with ciliate margin, inside glabrous; bracts subtending flowers ovate, 0.4–0.5 by 0.2–0.5mm, outside sericeous, inside glabrous. Brachyblasts knob-like, 0.5–0.7 mm long, with 2 or 3 flowers, sericeous. Pedicels 3–7 mm long, sericeous. Bracteoles at the top or the upper part of the pedicels, ovate, 0.3–0.4 by 0.2–0.3 mm, outside slightly pubescent, inside glabrous. Calyx cup-shaped, 2–3 mm high, maroonish, outside thinly sericeous, margin ciliate, inside glabrous, tube 2.5–2.8 mm high, upper lip with 2 short lobes, shallowly notched, 0.3–0.4 by 3–4mm; lateral and lower lobes shortly triangular, 0.5–0.6 by 1.5–2 mm, apex obtuse or rounded. Corolla purplish. Standard: claw 2.7–3 mm long; blade broadly elliptic to orbicular, 6–6.5 by 8–8.5 mm, apex emarginate, basal callosities absent, outside slightly ciliate at apex, inside glabrous. Wings: claw 1.7–3 mm long; blade elliptic, 6–7 by 1.7–2.3 mm, apex rounded, outside slightly hairy and ciliate at the apex, inside glabrous, auricle ca. 0.5 mm long. Keel petals: claw ca. 2 mm long; blade boatshaped, 6–6.5 by ca. 3 mm, apex rounded, outside thinly sericeous near the apical part and ciliate at apex, inside glabrous, upper auricle indistinct, 0.1–0.2 mm long, lateral pocket 1.2–1.7 mm long. Stamens monadelphous, with basal fenestrae, 7–8 mm long, free part 2–3 mm long, glabrous; anthers ca. 0.5 by 0.4 mm, glabrous. Disc indistinct. Ovary 4.5–5 mm long, thinly sericeous; ovules 2 or 3; style 3.5–4 mm long, slightly hairy at base or sometimes glabrous. Pods broadly straplike, flat, 4–9.5 by 1.5–2.6 cm, glabrous, with wing along both sutures, upper wing 3–4 mm wide, lower wing ca. 2 mm wide. Seeds unknown.