Annual or short-lived hairy perennial, with long-running or trailing ± scabrid stems bearing branched tendrils. Petioles scabrid, hollow, to c. 20 cm long. Lamina to c. 18 × 20 cm (larger in cultivation), broad-ovate, 5-7-lobed, densely puberulent especially beneath, with longer scabrid hairs on both sides; sinuses between lobes narrow and deep, rounded at the bottom; margins ± denticulate; base very broadly cordate with wide sinus. Peduncles of ? fls puberulent, to at least 25 cm long; peduncles of ? fls ± expanded at apex at fruiting. Calyx 17-25 mm long, lobed 1/2-⅔; lobes linear- subulate, puberulent and with scattered longer hairs. Corolla 7-10 cm long, hairy on both sides; lobes 3-5 cm long, involute, with apical green mucro. Anther mass c. 1.5-2 cm long. Perianth of ♀ fls similar to ♂, but somewhat larger. Fr. usually 15-25-(30) × 13-22 cm, broadly oblong-ellipsoid; rind mottled green and white, hard and shell-like, smooth; pulp white; stalks thick but not expanded at apex. Seed ellipsoid, very dark brown or black; margin obtuse, not raised.