Climber to 10 m. Tubers (1–)2–5(–20), c. 12–15 by 16–20 cm, usually digitate, ovate or globose in cultivated plants, but often cylindric to irregularly lobed in wild forms, annually to perennially replaced, shallowly buried, crown bearing thicker roots and sometimes several rigid thorny roots (especially in wild races). Indumentum of T shaped hairs present on all parts, stalks 0.05–0.3 mm long, bodies 0.7–2 mm long. Stems 3–12 mm in diam., twining to the left, terete, annual, toward base woody and densely spiny, spines lax on distal stems. Leaves simple, alternate, blade broadly ovate to orbicular, chartaceous, 7–9(–11)-veined, margins entire, base cordate, apex acuminate; petioles 6–14 cm long, terete; lateral nodal spines present, 2.5–6.5 mm long, straight or curved; cataphylls and bulbils absent. Inflorescences pendent, simple, tepals inserted on cup-shaped torus, fused at base; male inflorescences racemose, 1–2 per axil, peduncles 1.7–5 cm long, axes 9.5–25(–50) cm long; flowers solitary, 2.5–4 mm in diam. at anthesis, pedicels 0.8–1.2 mm long; female inflorescences spicate, 1–2(–3) per axil. Male flowers with outer and inner tepals 2.2–2.4 by 0.7–0.9 mm, narrowly oblong, oblong-elliptic or lanceolate to narrowly obovate, stamens 6. Capsules c. 26 by 25 mm, very rarely set (only one capsule was seen on Kerr 9051, K sheet). Seeds not seen.