A tree occasionally over 100 ft high, with a trunk 3 or 4 ft in diameter. In young trees the branches are erect, but become more spreading in older ones, forming eventually a compact, rounded head. Branchlets glabrous. Leaves probably the largest among maples, usually from 6 to 12 in. across, and cut more than half-way to the base into three or usually five lobes, each one being again cut into large, triangular minor lobes; ciliate; upper surface glossy green, lower one paler, with tufts of white hairs in the axils of the veins; leaf-stalk containing milky sap. Flowers yellow, scented, produced in April on dense pendulous racemes 4 to 6 in. long, each flower 1⁄3 in. across. Fruits covered with long, pale brown bristles; the wings nearly glabrous, 11⁄2 in. long, 1⁄2 in. wide, diverging at about 90°.
Native of the coast regions of western N. America from S. Alaska to California. It was introduced by Douglas for the Horticultural Society in 1826 or 1827, but had been discovered by Archibald Menzies more than thirty years before. In many respects it is the noblest of maples, and it thrives well in many parts of the British Isles. Owing to the late growth of young trees during mild autumns, they are apt to be cut back in hard winters; but otherwise it is absolutely hardy at Kew, where there are several good specimens. On young trees the leaves are larger, but not so deeply lobed. It flowers and bears seed in great quantities some seasons, and the keys are very frequently in threes instead of the usual pairs. Owing to their hairiness and the great size of the wings, the fruits are particularly striking. The timber is highly valued in N.W. America for furniture and indoor work – more so than that of any other tree of those regions except conifers.
The largest specimens of this maple recorded in recent years are fairly well distributed over the British Isles: Westonbirt, Glos., 75 × 91⁄4 ft (1965); Kew, 67 × 8 ft (1963); Syon House, Middlesex, 65 × 51⁄4 ft (1959); Dawyck, Peebl., 58 × 43⁄4 ft (1966); Tortworth, Glos., 47 × 61⁄2 ft (1966); Hungerford Priory, Wilts, by the cross-roads, 45 × 6 ft (1956). In Ireland there are two large specimens at Trinity College, Dublin; one, in the New Quadrangle, is 50 × 91⁄2 ft, the other, in the Main Quadrangle, 55 ft (estim.) × 10 ft (1966).