Stem rather robust, sulcate-angular, pubescent. Tendrils robust, often 3-fid, puberulent. Petiole 8-12 cm; leaf blade suborbicular, 15-20 × 15-20 cm, membranous, often 5-7-lobed; median lobe broadly triangular, lateral lobes smaller, both surfaces puberulent, margin dentate, apex acute or acuminate; sinus surrounded.

Male flowers 17-20 in raceme at the apex of peduncle; peduncle 10-15 cm; pedicels 1-4 cm, white puberulent; calyx tube campanulate, 5-8 × ca. 10 mm; segments lanceolate, 4-6 × 2-3 mm, densely white pubescent, 1-veined, apex acuminate, slightly reflexed; corolla yellow, rotate; segments obcordate, 15-25 × 10-20 mm, both surfaces subglabrous; stamens 3, free; filaments 4-5 mm; anthers puberulent. Female flowers solitary; ovary terete, longitudinally 8-10-angled; style short; stigmas expanded, 2-lobed.

Fruit cylindric or clavate-oblong, 8-10-angled, 15-40 × 6-10 cm, glabrous. Seeds black, ovoid, 11-12 × 7-8 mm, ca. 1.5 mm thick, margin without wing. Fl. and fr. summer and autumn.