Description from Flora of China
Urtica melastomoides Poiret, Encycl. Suppl. 4: 223. 1816; Pilea cuneatifolia Yamamoto; P. ovatinucula Hayata; P. trinervia (Roxburgh) Wight; Urtica trinervia Roxburgh.
Herbs perennial, robust or subshrubs, stoloniferous, glabrous, monoecious or dioecious. Stems blue green when dry, to 200 cm tall, ca. 1 cm in diam., succulent distally, woody at base, swollen between nodes, upper internodes shorter. Stipules persistent, triangular, ca. 2 mm, membranous; petiole equal in length, 2-9 cm; leaf blade abaxially pale green, adaxially often dark green or brownish, elliptic to elliptic-lanceolate, subequal in size, 10-23 × 5-16 cm, membranous, 3-veined, lateral veins many, spreading and regularly transverse, cystoliths fusiform, minute, often conspicuous abaxially, base cuneate or rarely subrounded, margin shallowly serrate or crenate, apex cuspidate or acuminate. Inflorescences solitary, male inflorescence a cymose-panicle, 15-35 cm overall, peduncle long and thick; female ones often shorter than petioles. Male flowers subsessile, in bud ca. 1 mm; perianth lobes 4, elliptic, apex acute or sometimes corniculate; stamens 4; rudimentary ovary minute. Female flowers subsessile, in bud ca. 0.8 mm; perianth lobes connate at base, subequal, abaxial lobe larger, subapically corniculate; staminodes 3, scale-like, oblong. Achene brownish, ellipsoid-ovoid, ca. 1 mm, compressed, almost not oblique, smooth or verrucose, with a slightly elevated ring by margin. Fl. Aug-Sep, fr. Oct-Nov.
Broad-leaved forests, shaded wet places by streams; 700-1800 m. SW Guangxi, Guizhou, Hainan, Taiwan, SE Xizang, S Yunnan [India, Indonesia, Sri Lanka, Myanmar, Vietnam].