Derris reticulata Craib

         Lianas, basal diameter 3–10 cm. Bark thin, smooth, light brown. Twigs 3–5 mm diam., glabrous, lenticellate. Leaves usually with 5(–7) leaflets Stipules caducous, triangular, 1.2–1.5 x 1.4–1.5 mm, outside sericeous, inside glabrous. Petiole 2–6 cm long, grooved above, glabrous or with some scattered hairs, rachis 2.5–5 cm long, pulvinus 4–6 mm long. Stipellae absent or reduced to hairy knob-like structures. Leaflets: subcoriaceous, terminal one (narrowly) elliptic to (narrowly) obovate, 6.5–13 x 2.5–4 cm, length/width ratio 2.6–3.3, base cuneate to obtuse, apex acuminate, acumen ca. 9–15 mm long, rounded, upper surface glabrous, lower surface glabrous except along the midrib with some scattered hairs, midrib flat or slightly raised above, distinctly raised below, veins flat above, raised below, 6–11 per side, 8–13 mm apart, not reaching the margin but curving towards the apex, sometimes anastomosing near the margin, venation reticulate; lateral ones (narrowly) elliptic to (narrowly) ovate, 5.5–12 x 1.5–4 cm, length/width ratio 2.2–3.6, base broadly cuneate to obtuse, apex acuminate, acumen 5–7 mm long, rounded, above glabrous, below glabrous except along the midrib with some scattered hairs; pulvinus 3–4 mm long. Inflorescences axillary or (rarely) terminal, pseudoracemes/ pseudopanicles, 2.5–15 cm long, striate, sericeous; peduncle up to 1 cm long, striate, sericeous; lateral branches up to 7 cm long. Bracts subtending brachyblasts ovate to narrowly triangular, 1–2 x 0.6–0.8 mm, outside pubescent, inside glabrous. Brachyblasts knob-like to elongate and cylindrical, ca. 9 mm long, (thinly) sericeous, with 1–4 flowers throughout, if 1, 2 or 3-flowered, then flowers sometimes seemingly at apex of the brachyblast, near the top of the inflorescence brachyblast sometimes disappearing and then flowers solitary (see D. tonkinensis). Bracts subtending flowers ovate or triangular, ca. 1 x 0.4–0.6 mm, outside pubescent, inside glabrous. Pedicels 7–10 mm long, (thinly) sericeous. Bracteoles in the middle or upper part of the pedicels, ovate or triangular, 0.6-0.8 x 0.4 mm, outside pubescent, inside glabrous. Calyx reddish or greenish-red, cup-shaped, 3–4 mm high, outside (thinly) sericeous or glabrescent, margin ciliate, inside glabrous, tube 2–3 mm high, upper lip with 2 short triangular lobes, 0.3–0.5 by 2–2.5 mm; lateral lobes triangular, 1–1.5 by 1.5–2 mm; lower lobe triangular, 1–1.3 by ca. 2 mm. Corolla white. Standard: claw 3–3.5 mm long; blade broadly obovate to orbicular, 8–10 by 7–8 mm, apex emarginate, basal callosities absent, outside thinly pubescent at apex, sometimes glabrescent, inside glabrous or with some hairs in the middle. Wings curved backward to the calyx claw 1.5–2 mm long; blade elliptic, 7–9 by 1–2 mm, apex rounded, outside glabrous or thinly ciliate at apex, inside glabrous, upper auricle up to 1.5 mm long, lower auricle indistinct, 0.1–0.5 mm long. Keel petals: claw 2–2.5 mm long; blade boat-shaped, 7–8 by 2.7–3 mm, apex rounded, outside glabrous or thinly ciliate at apex, inside glabrous, upper auricle ca. 1 mm long, lateral pocket 1–2 mm long. Stamens monadelphous, with basal fenestrae, 9–11 mm long, free part 2–3 mm long, glabrous; anthers ca. 0.2 by 0.25 mm, glabrous. Disc indistinct or annular, up to 0.1 mm high. Ovary up to 7 mm long, stipe indistinct, sericeous; ovules 2 or 3; style 2.5–3 mm long, thinly hairy at base. Pods strap-like or sometimes ellipsoid, 5–9.5 x 1.5–2.5 cm, thin, with a wing along both sutures, upper wing 4–7 mm wide, lower wing 2–3 mm wide, with some scattered short hairs, especially on both wings, or sometimes glabrescent, seed chamber indistinct, but usually slightly thickened and with reticulate veins around the seed. Seeds 1–2 per pod, discoid or bean-shaped, 11–13 x 6–6.5 x 1.5–2.5 mm; hilum central, 0.5–1 mm long.