Perennial herb. Root to 1 m. long, tuberous, fusiform. Stems annual, to 6 m., prostrate, ± hirsute, glabrescent. Tendrils solitary, spiniform. Leaflamina 3–18 × 2·5–14 cm., ovate to broadly ovate in outline, cordate, scabrid and ± pilose especially on the main veins above, rather softly asperulous-tomentose to strongly scabrid beneath, usually deeply palmately 5-lobed, the lobes lanceolate to elliptic or sometimes broadly so, usually deeply pinnately lobulate and often ± sinuate at the margins, acute, usually acuminate, apiculate, the central much the largest. Petioles 0·7–7·5 cm. long, hispid, scabrescent. male flowers solitary; pedicels 0·3–2 cm. long, hispid or villous; receptacle-tube 3·5–6 mm. long, pale green, hispid, lobes 3·2–6 × 0·7–1·5 mm., remote, lanceolate, usually slightly expanded above the middle, acuminate, acute. Petals 1·4–2·5 × 0·9–1·3 cm., yellow to white, obovate-elliptic, rounded, apiculate. Stamens 3. female flowers solitary; pedicels 2–8 cm. long; ovary 8–15 × 4–8 mm., ellipsoid; spines short, thick; receptacle-tube 3 mm. long, lobes 3–4 mm. long, subulate; corolla as in male flowers; staminodes 3, small. Fruit 6–12 × 4–8 cm., ellipsoid or subglobose, rather glaucous green, becoming pale yellow when mature, covered with prominent seta-tipped spines; fruit stalk rather slender, c. 6 cm. long. Seeds 7·5–10 × 4–6 × 2·5–3 mm., pallid-stramineous.
