Rhizome horizontal, much branched, cylindric, 2--5 cm thick, soft, spongy; cork light yellow. Stem twining to left, glabrous. Leaves alternate, simple; petiole to 12 cm; leaf blade drying greenish, abaxially grayish white, triangular or ovate-cordate, sometimes palmately 5--9-lobed basally on stem, 11--14 × 7.5--12 cm, adaxially glabrous, abaxially densely minutely setulose to puberulent, basal veins 9 or 11, reticulate veins prominent, base cordate with rounded sinus, margin entire to distinctly toothed, apex and lobes acute to acuminate. Male spike branched or forming an axillary panicle, lax, to 15 cm, sometimes forming terminal panicles by reduction of apical leaves. Male flowers: solitary or paired; pedicel 0.5--1 mm; bracts lanceolate, ca. 1 mm; bracteole borne at base of pedicel, minute; perianth orange, tube 1--1.5 mm wide, lobes spreading at anthesis, oblong-lanceolate, 2--2.5 mm, apex rounded; stamens 6, inserted at base of perianth, erect, ca. 1/2 as long as perianth lobes. Female spikes 12--30 cm, sometimes branched. Female flowers: staminodes filiform. Capsule dark brown, ± shiny, 1.3--1.6 cm, base ± truncate, apex emarginate; wings 1.5--1.6 cm wide. Seeds inserted near middle of capsule, winged all round, middle part narrower. Fl. Jun--Aug, fr. Jul--Oct.
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