Description from Flora of China
Sponia angustifolia Planchon, Ann. Sci. Nat., Bot., sér. 3, 10: 326. 1848; Celtis angustifolia Lindley; S. sampsonii Hance; Trema lanceolata Merrill; T. sampsonii (Hance) Merrill & Chun.
Shrubs or small trees to 7 m tall, dioecious or monoecious. Branchlets slender, reddish purple, gray when dry, densely hirsute. Stipules filiform, to 3 mm. Petiole 2-5 mm, densely hirsute; leaf blade lanceolate to narrowly lanceolate, 3-7 × 1-2 cm, papery to somewhat leathery, abaxially grayish white when dry, surface completely hidden by tomentose hairs, and with inconspicuous rust-colored glandular hairs on veins, adaxially dark green, very scabrous, and blackening when dry, base rounded to rarely ± cordate, margin denticulate, apex acuminate to caudate-acuminate; basally 3-veined; secondary veins 2-5 on each side of midvein. Flowers unisexual, clustered in cymelets as long as or longer than petiole. Male flowers: subsessile, ca. 1 mm in diam.; tepals 5, narrowly ovate, incurved, inside densely hirsute. Drupes reddish orange when mature, ± compressed, 1.5-2.5 mm, rugate, glabrous; perianth persistent. Fl. Apr-Jun, fr. Aug-Nov.
The fiber is used for manufacturing paper and textiles and the leaves are used as emery cloth.
Forests or scrub on sunny slopes; 100-1600 m. Guangdong, Guangxi, Hainan, S Yunnan [India, Indonesia, Malaysia, Thailand, Vietnam].