A deciduous tree 20 to 50 ft high. Leaves five; more rarely three-lobed, 2 to 4 in. across, bright green above, paler, rather glaucous and glabrous beneath, except for a patch of down at the base and along the chief veins; stalk about as long as the blade. The three central lobes are parallel-sided, and each has several large, angular, blunt teeth; basal pair of lobes ovate. Flowers greenish yellow, produced during April in short-stalked corymbs. Fruit glabrous; keys 3⁄4 to 1 in. long; wings nearly parallel, 1⁄4 in. wide.
Native of S.E. Europe but represented in W. Asia by forms and varieties that differ to a greater or lesser degree from the plant described above. Even in S.E. Europe it is variable, and forms with small, leathery leaves found in Greece are sometimes regarded as a distinct species (A. reginae-amaliae Boiss.). A. hyrcanum is allied to A. opalus, but differs in the deeper and more angular lobing of the leaf. The form introduced is a slow-growing tree of neat shape. There are specimens 45 ft high at Westonbirt and in the University Parks, Oxford.