Stem branched, robust, pubescent at first, ultimately glabrous. Tendrils smooth, glabrous, to 20-30 cm. Petiole robust, 1.5-8 cm, pubescent at first, later glabrous; leaf blade broadly ovate-cordate, 15-25 × 12-20 cm, leathery, margin entire or rarely in younger leaves distinctly and minutely toothed near base, scabrous on veins, otherwise glabrous on both surfaces, apex shortly acuminate. Male panicle to 17 cm; rachis and branches scabrous; bracts 5-9 mm; bracteoles 2-3 mm; calyx segments ovate-lanceolate, longer than corolla segments, ca. 6 mm; corolla segments ovate-lanceolate, ca. 4 mm, outside sparsely and minutely hairy, inside papillose. Fruit oblong, 3-6 in clusters on a long stalk, ca. 30 cm, indehiscent with a thick woody rind. Seeds 3.5-4 × ca. 2 cm, ca. 0.5 cm thick. Fl. and fr. Aug.