Hornbeam, the name of several hardy trees of the birch family. Hornbeams are often cultivated for their ornamental foliage. There are about 20 species, most of them native to Europe and Asia.

Hornbeams are dense, rather rounded trees ranging from 25 to 75 feet (8 to 23 m) in height. They have smooth, gray bark and bright-green, oval leaves with sharply toothed edges. The male flowers are drooping, cylindrical, scaly catkins. The female flowers are small catkins that grow at the ends of twigs. The fruit is a ribbed nutlet. Hornbeams have tough, hard, whitish wood that is used chiefly for tool handles and for making charcoal.

The common European hornbeam, from 50 to 70 feet (15 to 21 m) high, is often grown in parks and large estates. It is found from Great Britain eastward to Iran. The American hornbeam, also called blue beech, averages about 30 feet (9 m) in height. It is widely distributed in the eastern United States. The hop hornbeam, or ironwood, from 20 to 40 feet (6 to 12 m) high, has fruits that resemble hops. It is found from the Atlantic coast westward to Minnesota and Texas.

The European hornbeam is Carpinus betulus; American, C. caroliniana; hop, Ostrya virginiana. Hornbeams belong to the family Betulaceae.