Tree 20–25 m. Bark brown. Branchlets glabrous, remaining green for several years. Leaves deciduous, 5–15 cm across, orbicular, palmately 3– to 5-lobed, lobes shallow, both surfaces glabrous, margins subentire to sinuate; petiole 1–4 cm long, slender, exudes milky sap when broken. Inflorescence not seen. Samaras ~4 cm long, wings diverging at 45°; nutlets striped or veined (van Gelderen et al. 1994; Rushforth 1995).
Distribution China Yunnan Vietnam
Habitat Broadleaved, mesic forest between 1600 and 1800 m asl.
USDA Hardiness Zone 8-9
RHS Hardiness Rating H5
Conservation status Not evaluated (NE)
Taxonomic note Xu et al. (2008) treat this taxon as a synonym of Acer amplum subsp. bodinieri. However, it is treated as distinct here until further information to indicate otherwise is available. van Gelderen et al. (1994) included it within Section Palmata Series Sinensia, though this confusion was swiftly resolved by Rushforth (1995).
Acer chapaense seems to have first been collected and introduced by Bob Cherry and Keith Rushforth during an expedition to Vietnam in 1992. It became established in Bob Cherry’s arboretum at Kulnura, New South Wales, whence seed from the cultivated trees has been distributed, and appears true to type. A plant from this source is growing strongly at Hergest Croft, at over 4 m tall as of July 2019. A plant at Westonbirt Arboretum promises much in spring but never reaches its potential and is something of a runt. It was either planted too deep or sunk following some overzealous soil disturbance at planting time. It currently remains as a good example of poor practice.
Grimshaw & Bayton (2009) note that plants, at least when young, resemble members of the Acer campbellii group (Section Palmata Series Sinensia), though this likeness is superficial and entire leaf margins and the presence of milky sap easily extracted from the leaf petioles of A. chapaense separate it from all members of that group. The inclusion of the species as part of the A. campbellii group by van Gelderen et al. (1994) was largely a result of those authors not being familiar with it and arriving at the wrong conclusion about where it ought to be placed. The leaves of A. chapaense are leathery, with a faint velvety feel to the underside, and flush red-bronze. They persist on the tree for much of the winter, falling in January, not long before the new shoots break. Rushforth (1995) noted that in Vietnam he observed it growing in wet forest with a number of broadleaved trees that are generally considered to be hardy, in the United Kingdom at least, but it should probably be given a sheltered site in a moist, fertile situation. It should be noted, however, that the species has not been seen on recent expeditions to parts of its range, and it is perhaps now extinct in Vietnam (Crowley 2018).