A small, deciduous tree with smooth, purplish young stems. Leaves three-lobed, or five-lobed with the basal pair of lobes very small; blades 31⁄2 to 51⁄2 in. long and about as wide, lobes triangular, prolonged at the apex into tail-like points which are often strikingly long and slender, sharply toothed, often doubly so, the midrib and main nerves of the under-surface covered at first with whitish or yellowish hairs but becoming glabrous except for hairs in the axils of the nerves near the base; leaf-stalks 13⁄4 to 4 in. long, covered with white down at first, later glabrous or remaining hairy near the apex. Male flowers in corymbs. Fruits in simple lax racemes 4 to 7 in. long, borne on pedicels 3⁄5 to 11⁄5 in. long; wings of fruit diverging at an acute angle, 11⁄8 to 13⁄4 in long with the nutlet, 1⁄3 to 1⁄2 in. wide.
Native of the W. Himalaya from Kashmir to Kumaon; date of introduction uncertain. For the reasons explained in the note, this species has been much confused with A. papilio (A. caudatum sensu Rehder) but is distinguished from that species by the soon glabrous leaves, the corymbose male inflorescence, and by the fruits being borne in long, lax racemes on pedicels much longer than in A. papilio; the fruits are also larger, with less spreading wings.
Acer acuminatum is represented in the maple collection at Kew by a specimen 18 ft high, raised from seeds received under the name “A. pentapomicum”.
Note: A. acuminatum was described by David Don (Prodr. Fl. Nepal., p. 249 (1825)) from a specimen collected at 'Sirinagur' by Kamroop, one of the native collectors employed by Nathaniel Wallich, who was for many years the Superintendent of the East India Company's Botanic Garden at Calcutta. Don took the name from one of Wallich's letters. The name A. acuminatum does not occur in the so-called Wallich Catalogue (the 'Numerical List' of the East India Company's herbarium which Wallich wrote), but under No. 1225 Acer caudatum there is material collected by Kamroop 'Ex alpibus Sirinagur', which agrees with A. acuminatum. Indeed, all the material under this number is A. acuminatum except for one sterile specimen which may be A. papilio. When Wallich came to describe his A. caudatum (Pl. As. Rar., Vol. 2, p. 4, p. 28 and t. 132 (1831)), he cited the collections he had enumerated under No. 1225 and therefore A. caudatum Wall. consists, in part, of A. acuminatum.
From the Supplement (Vol. V)
A. acuminatum is a dioecious species, allied to A. argutum and A. barbinerve. It is now known to extend farther east than Kumaon, having been collected recently in various parts of Nepal. There is an example in the Edinburgh Botanic Garden, measuring 52 × 31⁄2 ft (1985), and there are young plants at Wakehurst Place, Sussex, from seeds collected in eastern Nepal (Schilling 2286).