山黄麻 shan huang ma

Celtis tomentosa Roxburgh, Fl. Ind., ed. 1832, 2: 66. 1832; C. amboinensis Willdenow, p.p.; Sponia amboinensis (Willdenow) Decaisne, p.p.; S. tomentosa (Roxburgh) Planchon; S. velutina Planchon; Trema amboinensis (Willdenow) Blume, p.p.; T. dunniana H. Léveillé; T. velutina (Planchon) Blume.

Trees or shrubs, to 10 m tall. Bark grayish brown, smooth or fissured. Branchlets grayish brown to brown, densely grayish brown to gray pubescent. Stipules linear-lanceolate, 6-9 mm. Petiole 0.7-1.8 cm, pubescent; leaf blade grayish brown to black-brown when dry, 7-15(-20) × 3-7(-8) cm, abaxially with grayish brown pubescence, surface of blade visible between hairs under magnification, adaxially very scabrous with erect bristles, base cordate and oblique, margin denticulate, apex acuminate, caudate-acuminate, or rarely acute; basally 3-veined; secondary veins 4 or 5 on each side of midvein. Male inflorescences 2-4.5 cm. Female inflorescences 1-2 cm. Male flowers: subsessile, 1.5-2 mm in diam. Ovary rudimentary, obovate-oblong, compressed, transparent. Female flowers: shortly pedicellate. Tepals 4 or 5, triangular-ovate, 1-1.5 mm. Ovary glabrous. Drupes brownish purple to blackish purple when mature, compressed, 2-3 mm in diam., irregularly rugate, glabrous; perianth persistent. Seed broadly ovoid, compressed, 1.5-2 mm, ribbed. Fl. Mar-Jun (but year-round in tropical zones), fr. Sep-Nov.

Forests, moist valleys, open slopes;; 100–2000 m. S Fujian, Guangdong, Guangxi, Guizhou, Hainan, SW Sichuan, Taiwan, S Xizang, Yunnan [Bangladesh, Bhutan, Cambodia, Japan (Ryukyu Islands), Laos, Malaysia, Myanmar, Nepal, Pakistan, Sikkim, Vietnam; NE Australia, E Africa, Madagascar, Pacific Islands].

The pubescence of the leaves is very variable, and it is often difficult to distinguish Trema tomentosa and T. orientalis. Some authors have considered T. tomentosa to be a synonym of T. orientalis.

The wood is fine and strong, tannin is extracted from the bark, the fibers are used for manufacturing paper, ropes, and staple rayon, and the leaves are used as emery cloth.