Female flowers in fascicles of 2–3 or rarely solitary; peduncles 1·5–3 cm. long; pedicels 1–8 mm. long; ovary 7–10 × 2–3 mm., glabrous; petals unequal, 3 broader, erect, 8–10 mm long, 2 reflexed or spreading, narrower, 7–8 mm. long.
male flowers 5–50 in lax paniculoid axillary fascicles; peduncles and pedicels 2–20 mm. long. Receptacle-tube 0·5 mm. long; lobes 2–4 mm. long, ovate-lanceolate or triangular, acute. Petals brownish yellow, sometimes tinged orange or pinkish, unequal, the two larger 10–18 mm. long, oblong, erect, the three smaller 9–16 mm. long, linear, much narrower, reflexed, paler; anther-connective produced apically into a small appendage.
Seeds 25–44 mm. long, with fusiform little-compressed body and broad wing; body 12–22 × 1·8–3·5 mm., wing 14–22 × 6–9 mm.
Fruit 4·5–6·3 × 1·8–2·8 cm., cylindric-obconic, smooth, glabrous, obscurely veined.
Scandent to 6 m.; stems becoming woody when old, arising from convex greenish semi-subterranean tuberous rootstock up to 50 cm. or more across.
Leaf-lamina 3–10 × 4·5–12·5 cm., broadly to very broadly ovate in outline, cordate, subsucculent, almost glabrous, palmately 5–7-lobed or less often unlobed; lobes triangular or ovate-triangular, obtuse to acute, shortly acuminate, apiculate, the central largest.
Petiole 1·5–8 cm. long, sparsely shortly crispate-pubescent.
Perennial climber to 6 m.; stems subsucculent, becoming rather woody with smooth greyish bark, expanded at the base into a greenish dome-like semi-subterranean tuber up to 50 cm. or more across.
Leaf-blade broadly ovate- or reniform-cordate in outline, slightly fleshy, somewhat glaucous, practically glabrous, 31–100 mm. long, 44–124 mm. broad, ± deeply 5-lobed, less often unlobed; lobes triangular, ± shortly acuminate, apiculate; petiole very sparsely short-hairy or glabrous, 15–80 mm. long.
Male flowers 4–45 or more in 20–100 mm. long panicles; peduncles 2–15 mm. long; pedicels 2–20 mm. long; receptacle-tube shallow; lobes ovate-lanceolate, 2–4 mm. long; petals brownish-green or dull brownish-orange, unequal, 2 large, oblanceolate, erect, 10–18 mm. long, 2.5–5.5 mm. broad, 3 small, linear, reflexed, rather paler, 9–16 mm. long, 1–2 mm. broad; stamens 4, connate by the anthers into two pairs; connective apically produced; fifth (unpaired) stamen represented by a subulate staminode.
Female flowers sometimes solitary, more usually 2–3 in panicles on 15–30 mm. long peduncles; pedicels 1–8 mm. long; ovary trigonous, 7–10 mm. long, 2–3 mm. across; receptacle-lobes ovate-lanceolate, 2–2.5 mm. long; petals unequal, 3 broad, erect, 8–10 mm. long, 2–2.5 mm. broad, 2 spreading or reflexed, 7–8 mm. long, 1 mm. broad.
Seeds fusiform, with a broad somewhat asymmetrically inserted wing, 25–44 mm. long, with the body of the seed 12–22 mm. long, 1.8–3.5 mm. across and the wing 14–22 mm. long, 6–9 mm. broad.