A deciduous tree with smooth purplish or brownish to grey young shoots. Leaves three- to five-lobed, but when five-lobed the basal lobes are sometimes very small; blades 3 to 53⁄5 in. long and as much or slightly more wide, lobes triangular to ovate, acuminate to caudate, finely and sharply saw-toothed, often doubly so, the teeth furnished with bristly tips, midrib and veins on the lower surface covered at first with a mealy, rust-coloured indumentum, but later becoming more or less glabrous except in the axils of the nerves at the base. Flowers in spikes. Fruits in compact racemes 23⁄5 to 4 in. long, borne on short pedicels 1⁄6 to 2⁄5 in. long; keys widespreading (often horizontally), 4⁄5 to 1 in. long, the wings 1⁄5 to 2⁄5 in. wide.
Native of the Himalaya from Nepal eastward, and of Upper Burma (possibly also of Yunnan). It has been much confused with A. papilio (A. caudatum sensu Rehder), from which it is readily distinguished by the fine, bristle-tipped teeth of the leaf-margins, by the mealy, rust-coloured indumentum of the under-surface of the young leaves, and by the racemose inflorescence (in A. papilio the inflorescence is a narrow panicle which becomes racemose only in the fruiting state). A. pectinatum is a little known species, but of considerable interest as the only Himalayan representative of the section Macranthsa, to which the ‘snake-bark’ maples belong.