Rhizome horizontal, irregularly cylindric, 1--3.5 cm thick, hard, drying rich in starch; cork yellowish brown. Stem twining to left, glabrous. Leaves alternate, simple; petiole to 5 cm; leaf blade drying dark grayish, ovate-triangular, palmately bluntly 7-lobed basally on stem, to 10 × 11 cm, slightly leathery, uniformly hispidulous, densely so abaxially, reticulate veins prominent, base deeply cordate, margin entire or slightly undulate, apex acuminate. Male spikes to 7 cm, in axillary panicles to 20 cm. Male flowers: solitary or occasionally paired; pedicel 1--1.5 mm; bracts lanceolate; perianth yellow, turning orange, drying black, funnelform, lobes spreading at anthesis, oblong-ovate, 1.5--2 mm, apex rounded; stamens (3 or)6, inserted at base of perianth tube; staminodes sometimes present. Female spikes to 7 cm, few flowered. Female flowers: staminodes with sterile anthers or filaments only. Capsule dark brown, not shiny, broadly obovoid, 1.5--1.8 cm, base rounded, apex slightly emarginate to truncate; wings 1--1.2 cm wide. Seeds inserted near middle of capsule, 4--5 mm in diam. (excluding wing), winged all round. Fl. Jun--Jul, fr. Jul--Oct.
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