Description from Flora of China
Tubers globose, ovoid, gourd-shaped, oblong, or cylindric; cork dark brown; transverse section light brown or red, drying purplish black. Stem twining to right, branched, green, to 20 m, glabrous, prickly at base. Leaves alternate basally on stem, opposite distally on stem, simple; petiole 2--6 cm; leaf blade adaxially dark green, abaxially whitish, ovate to linear, 5--20 × 0.6--14 cm, leathery or subleathery, glabrous, basal veins 3 or 5, reticulate veins prominent, base rounded, sometimes triangular lobed, margin entire, apex acute or acuminate. Male spikes 2--10 cm, in axillary panicles 2--14 cm or longer; rachis straight. Male flowers: outer perianth lobes ovate or broadly so, ca. 2 mm, inner ones obovate; stamens 6, slightly shorter than perianth lobes. Female spike solitary, to 12 cm. Capsule not reflexed, oblate, 1.8--3.5 cm, base emarginate, attenuate into pedicel ca. 7 mm, apex emarginate; wings 1.2--2.7 cm wide. Seeds inserted near middle of capsule, 1.8--2.4 cm in diam. (ca. 0.6 cm excluding wing), winged all round, Fl. Apr--Jun, fr. Jul--Jan.
The tubers have a very high tannin content and are used to dye and preserve fabrics.
Mixed forests, broad-leaved forests, scrub forests, mountain slopes, valleys, along rivers, roadsides; near sea level to 1500 m. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hunan, S Jiangxi, S and W Sichuan, Taiwan, SE Xizang, Yunnan, S Zhejiang [Thailand, Vietnam].