A small tree up to 30 ft high, of graceful habit, with long slender branches downy when young; winter buds not stalked. Leaves resembling those of a hornbeam, ovate-oblong to ovate-lanceolate, rounded or wedge-shaped at the base, more or less slender-pointed, finely toothed (often doubly so), 2 to 41⁄2 in. long, 1 to 2 in. wide, with many parallel veins; upper surface with flattened hairs between the veins, lower one downy, especially on the midrib and veins; stalk hairy, 1⁄6 in. to 5⁄8 in. long. Male catkins often solitary or in pairs, 2 to 3 in. long, opening in March and April. Stalk of female inflorescence glandular-hairy. Fruits 1⁄2 to 1 in. long, oval.
Native of Japan. It is variable in the degree of downiness of the leaves beneath and of the young stems. The more downy forms are distinguished as var. hirtella Franch. & Sav., which was introduced in 1894 as var. yasha and represents the species on the main island of Japan. Typical A. firma is said to be found only in Kyushu.
A. firma in the broad sense is common in the mountains of Japan and is also, as Sargent observes, largely planted on the margins of the fields of the Tokyo region to afford ‘support for the poles on which the freshly cut rice is hung to dry’. It is represented at Kew by two trees planted in 1893, the taller 40 × 4 ft (1967).
var. multinervis Reg. A. pendula Matsum. – A very distinct variety, often given specific rank. Leaves long, with eighteen to twenty-four pairs of veins, conspicuously double-toothed; stalks short, 1⁄6 to 1⁄4 in. long; fruits small, pendulous, little more than 1⁄2 in. long. This is the form originally introduced to Britain (1862).
var. sieboldiana (Matsum.) Winkler A. sieboldiana Matsum. – Branchlets glabrous, stout. Female catkins solitary. Native of the lower parts of the main island, commonest on the sea-coast.