Dioscorea zingiberensis C. H. Wright

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

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.

Gansu, S Henan, Hubei, Hunan, S Shaanxi (S of Qin Ling), Sichuan, Yunnan.

* Mixed forests; 100--1800 m.

Dioscorea zingiberensis, is a species of yam, a tuberous root vegetable. It has been cultivated in China for the production of diosgenin, an important pharmaceutical intermediate for the synthesis of steroid hormones. The rhizomes also produces steroidal saponins (TSS) as part of a treatment for cardiovascular disease.