A sub-evergreen or deciduous tree, found both in the Himalaya and China. In the Himalaya it grows 50 ft in height, but plants from that region are too tender for our climate. In China it appears to be most frequently 20 to 25 ft high. It is a tree without down; the leaves hard and leathery in texture, normally oblong or oblong-ovate, 2 to 4 in. long, 3⁄4 to 11⁄2 in. wide; pointed at the apex, tapered or rounded at the base, normally neither lobed nor toothed; distinctly glaucous beneath. In the Himalayan form the leaves may be up to 6 or 7 in. long. Flowers in downy panicles. Fruits glabrous; keys about 1 in. long; the wings about 1⁄4 in. wide.
Native of the Himalaya, W. and S. China; an allied species is found in Formosa. This species is variable in leaf; the venation may be quite pinnate or become three-veined by the proportionately stronger development of the basal pair of lateral veins. Young plants often bear distinctly three-lobed, sharply toothed leaves as well as the normal ones. Three-lobed leaves may also occur on adult trees and it was such a one that furnished the type of Henry’s var. trilobum, but this condition seems to be part of the normal variation of the species.
A. oblongum was introduced from the Himalaya in 1824 and a hardier form by Wilson in 1901. A tree at Kew from this seed died, but another, bought from Veitch in 1908, and almost certainly also from Wilson seed, proved hardy and is now 22 ft high (1960).
var. concolor Pax – Leaves green on both sides.
var. latialatum Pax – Wings of fruit broad, 1⁄2 in. wide, and almost semicircular. Described from a tree that once grew in the Botanic Garden, Florence, but reported from the wild.
A. paxii Franch. A. oblongum var. biauritum W. W. Sm. – Rehder concluded that this species is no more than a variety of A. oblongum and identified it with var. biauritum, founded on a specimen collected by Forrest in Yunnan. Fang, in his Monograph on the Chinese Aceraceae, agrees that they are identical but retains A. paxii as an independent species. It bears evergreen leaves, which are sometimes quite entire, but just as commonly three-lobed, and the two kinds of leaf may appear together on the same shoot. The lobes, sometimes no more than large teeth, are borne about midway up the leaf, which is broadly ovate to halberd-shaped, and up to about 21⁄2 in. long, 13⁄5 in. wide. The inflorescence is a corymbose panicle, as in A. oblongum. However, specimens of A. paxii in the Kew Herbarium have glabrous inflorescence branches (downy in the other species) and also show the following further marks of difference: A. paxii has longer petals and the nutlets of the fruit are rounded, while in A. oblongum they are more angular.
A. paxii was discovered by Père Delavay in Yunnan and is distributed over much of S. China. A plant grown at Kew under this name has survived recent hard winters but does not thrive. It agrees with A. paxii in its foliage, but in the absence of flower and fruit it cannot be identified with certainty.
A. buergerianum, at least in the normal wild form, resembles A. paxii in its polymorphic leaves, but these are deciduous.