Tree to 12 m, though often a shrub in cultivation. Bark greyish black, slightly white-striped. Branchlets red or brown, glabrous. Leaves deciduous to semi-evergreen, papery to leathery, 10–14 × 5–8 cm, entire or rarely three-lobed, upper surface dark green, lower surface pale green with barbed hairs in the vein axils, margins entire to serrulate, apex caudate; petiole 2–4 cm long, glabrous; autumn colour rather limited. Inflorescence terminal, racemose, with 40–50 flowers. Flowers rather small, 5-merous, staminate or hermaphrodite; sepals ~0.3 cm long, oblong-ovate, petals greenish yellow, same length as sepals, stamens eight, inserted inside the nectar disc. Samaras 2–2.5 cm long, brown, wings spreading obtusely, rarely horizontally. Flowering March, fruiting September (China). Van Gelderen et al. 1994, van Gelderen & van Gelderen 1999, Xu et al. 2008. Distribution BHUTAN; CHINA: southeast Xizang, Yunnan; INDIA: Assam, Sikkim; MYANMAR; NEPAL. Habitat Mixed forest between 1700 and 3000 m asl. May grow as an epiphyte. USDA Hardiness Zone 8–9. Conservation status Not evaluated. Illustration NT11. Cross-references B204 (as A. hookeri), K106.
Despite having a vast range Acer sikkimense is not very well known in cultivation, probably because it often occurs at rather low altitudes at lower latitudes. It was described by Bean (1976a), as A. hookeri, and stated by him to be tender in the British Isles, a view that seems to be borne out by the general dearth of specimens growing outside here. It is in cultivation at Tregrehan, from Chinese and Vietnamese origins. Except on the mildest fringes of western Europe or the Pacific Coast, however, it is probably too tender for outdoor use. Beyond our area it is grown in California and Australia.
Described by Peter Wharton (pers. comm. 2007) as an ‘intriguing’ species, it is clearly very variable, and Wharton noted that in northern Vietnam, at least, it occurs in populations that vary from evergreen to deciduous. This suggests that there is much variation to experiment with in cultivation.