Plants sometimes monoecious. Rhizome horizontal, sometimes irregularly branched, subcylindric, 1--1.5 cm thick; cork dull brown, rough; transverse section yellow. Stem twining to left, glabrous, smooth. Leaves alternate, simple; petiole 2.5--6 cm; leaf blade adaxially green, often irregularly spotted, drying dark grayish brown, narrowly peltate, triangular-ovate, usually ± 3-lobed by enlargement of basal lobes, 4.5--10 × 4--8.5 cm, papery, glabrous, base cordate with broadly rounded sinus, apex rounded and cuspidate to acuminate; lateral lobes reflexed, rounded. Male spikes solitary or 2 or 3 together, 5--10 cm, very slender, often borne along specialized, paniclelike, lateral shoots with reduced leaves. Male flowers: solitary or in cymules of 2 or 3, sessile; bracts 3 or 4, brown, membranous; perianth purplish red, drying black, lobes spreading at anthesis, 1.2--1.5 × 0.8--1 mm; stamens 6, inserted at margin of receptacle, filaments extremely short. Female spike to 8 cm. Female flowers: staminodes filiform. Capsule reflexed, long pedicellate, drying blue black, obovoid, 1.4--2 cm, about as long as wide, pruinose, base ± truncate, apex emarginate; wings 0.8--1.2 cm wide. Seeds inserted near middle of capsule, winged all round. Fl. May--Aug, fr. Sep--Oct.

The rhizome is an extremely important source of diosgenin for the drug industry. It is also an important traditional medicine.

* Mixed forests; 100--1800 m. Gansu, S Henan, Hubei, Hunan, S Shaanxi (S of Qin Ling), Sichuan, Yunnan.