Shrub or tree to 8 m, or more in cultivation. Bark pale or dark grey, smooth. Branchlets yellowish green to olive-brown, slender, glabrous and with round, raised lenticels. Leaves deciduous, thin and papery, tremulous, 4–6 × 3–6 cm, palmately three- to five-lobed, rarely entire, lobes shallow, upper surface dull dark green and glabrous, lower surface pale green with some caducous hairs along the veins, margins entire, apex acute or rarely acuminate; petiole 3–8 cm long, slender, pale green or reddish, exudes milky sap when broken; autumn colour yellow. Inflorescence terminal, corymbose, 1.5–2 cm long. Flowers 5-merous, staminate or hermaphrodite; sepals oblong to ovate, pale green, petals oblong-obovate, yellowish green, stamens 8–10, inserted outside the nectar disc. Samaras 2–2.2 cm long, purple when young, wings spreading nearly horizontally. Flowering May, fruiting September (China). Van Gelderen et al. 1994, van Gelderen & van Gelderen 1999, Xu et al. 2008; Gregory, in prep. Distribution CHINA: western Hubei, Jiangxi, Sichuan, Yunnan. Habitat Mixed forest between 1200 and 1800 m asl. USDA Hardiness Zone 6–7. Conservation status Not evaluated.
Acer tenellum is rare in cultivation, and dismissed by van Gelderen & van Gelderen (1999) as being of ‘botanical interest only’. Despite this it is represented in a number of British and European collections, the largest verified specimen being in the United Kingdom (11 m, dbh 36 cm, TROBI), at Borde Hill, West Sussex, probably grown from seed collected by Wilson in 1901 (van Gelderen et al. 1994). A taller tree (16 m) at Glasnevin is the subject of discussion over its identity. There is also some doubt over the authenticity of material offered commercially in the United States (Hill & Narizny 2004). Vegetative propagation is difficult (van Gelderen & van Gelderen 1999), but it is available from nurseries specialising in Acer. Its charm lies in its small, rather rounded leaves, said to quiver in the breeze like those of an Aspen (Populus tremula) (van Gelderen & van Gelderen 1999).