Tubers several in one year, thrust deep into the soil on long stalks; flesh soft and more or less esculent. Plant glabrous, of vigorous growth. Stems very prickly at the base and markedly furrowed, attaining 6 mm in diam., becoming unarmed upwards, climbing to 20 m and perhaps more. Bulbils none seen. Leaves opposed, firm, broadly lanceolate to elliptic-ovate, rounded at the base or just cordiform at the horizon of flowering (leaves in youth forms are sagittate), to 15 by 4½-5½ cm, sometimes larger even to 20 by 4½ cm, 5-7-nerved, the primary nerves with the peculiarity of the first pair not leaving the midrib at the base of the lamina, but curving away a few mm above; lower surface often suffused with a reddish purple colour (var. purpureovenia PRAIN & BURK. ex RIDL.); petiole about 4 cm long. Male flowering axes 1-4 together, assembled on large leafless branches that are produced high among forest trees and difficult to obtain; axes rather wiry, to 3 cm long and carrying about 30 flowers spaced about their own diameter apart. Buds sub-globose, 1½ mm long, sometimes with a small wart over the axis on the base. Female flowering axes solitary. Capsules slightly retuse at the apex, nearly truncate at the base; wings 20 by 22 mm; stipe to 6 mm long.
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