A small, bushy tree rarely 40 ft high, with a short, grey, fluted trunk; young shoots at first furnished with pale hairs. Leaves oval or ovate, 2 to 4 in. long, 1 to 2 in. wide; rounded or heart-shaped at the base, taper-pointed, sharply and often doubly toothed; covered with white silky hairs when quite young, becoming sparsely hairy above, downy on the midrib and vein-axils beneath; stalk 1⁄4 to 1⁄2 in. long, downy. Male catkins 1 to 11⁄2 in. long. Fruiting clusters about 3 in. long; the bracts three-lobed, 1 to 11⁄2 in. long; the middle lobe much the largest and nearly 1 in. wide, toothed (often on one side only).
Native of eastern N. America and Mexico; introduced in 1812. Although very similar to the European hornbeam it is not so fine a tree, growing more slowly and never attaining to so large a size. Its leaves turn a deeper, more orange-yellow, or even scarlet shade in autumn. In winter, the best distinction between the two species is afforded by the buds; these, in our native hornbeam, are slender and spindle-shaped, 1⁄4 in. or more long, and like small beech buds, but they are egg-shaped and only 1⁄8 in. long in the American one. The tallest example at Kew, planted in 1916, measures 40 × 21⁄2 ft (1967); there are four others of about the same age, averaging 30 × 2 ft.