Shrub or tree 8–12 m. Bark dark brown, smooth. Branchlets purplish green to olive-brown, glabrous and waxy. Leaves deciduous, somewhat leathery, 10–15 × 7–5 cm, palmately three- to five-lobed, lobes shallow, upper surface glabrous, lower surface glabrous but for the tufts of hair in the vein axils, margins entire in subsp. tonkinense and subsp. liquidambarifolium (serrate in young leaves and with remote teeth in subsp. kwangsiense), apex acute; petiole 2–3.5 cm long, purplish green; autumn colour orange-yellow to red. Inflorescence terminal, paniculate, 8–10 cm long with numerous flowers. Flowers 5-merous, staminate or hermaphrodite; sepals triangular, purplish green, petals yellowish, stamens 8–10, inserted outside the nectar disc. Samaras 1.8–3 cm long, yellowish, wings spreading horizontally. Flowering April to May, fruiting September (China). Van Gelderen et al. 1994, Xu et al. 2008. Distribution CHINA: Guangxi, southern Guizhou, southeast Xi-zang, southeast Yunnan; MYANMAR; THAILAND; VIETNAM. Habitat Mixed forest between 300 and 1800 m asl. USDA Hardiness Zone 8–9. Conservation status Not evaluated. Illustration NT76. Cross-reference K108. Taxonomic note Van Gelderen et al. (1994) recognised two subspecies with somewhat larger leaves: subsp. kwangsiense (W.P. Fang & M.Y. Fang) W.P. Fang, with leaves 12–17 cm across with sparse teeth on the margin (cultivated by Firma C. Esveld under glass in the Netherlands); and subsp. liquidambarifolium (H.H. Hu & W.C. Cheng) W.P. Fang, with evenly lobed leaves 8–14 cm across. The latter is said to be extremely beautiful in the wild in Vietnam (D. Hinkley, pers. comm. 2007), but grows at rather low altitudes. These subspecies are not accepted by Xu et al. 2008.
Acer tonkinense is extremely rare in cultivation and has not been seen in any collections visited in the research for New Trees. Such little information as can be gleaned suggests that it is not hardy in most of our area and must be maintained under glass. It has, however, recently been offered commercially, most notably by Heronswood Nursery in their 2002 catalogue. The plants offered were grown from seed supplied by James Waddick of Kansas City, Missouri, obtained from Shanghai Botanic Garden, and were described as having thick leathery leaves, each of the five lobes terminating in a long-acuminate point. At Heronswood it proved ‘very hardy’ and formed a notable feature with ‘ashen lime’ stems in winter (Heronswood Nursery catalogue 2002). It comes into growth early in the year (D. Hinkley, pers. comm. 2007).