The common English name hornbeam derives from the hardness of the woods (likened to horn) and the Old English beam "tree" (cognate with German Baum). The American hornbeam is also occasionally known as blue-beech, ironwood, or musclewood, the first from the resemblance of the bark to that of the American beechFagus grandifolia, the other two from the hardness of the wood and the muscular appearance of the trunk, respectively. The botanic name for the genus, Carpinus, is the original Latin name for the European species.
Hornbeams are small to medium-sized trees, Carpinus betulus reaching a height of 32 m.:296 The leaves are deciduous, alternate, and simple with a serrated margin, and typically vary from 3-10 cm in length. The flowers are wind-pollinated pendulous catkins, produced in spring. The male and female flowers are on separate catkins, but on the same tree (monoecious). The fruit is a small nut about 3-6 mm long, held in a leafy bract; the bract may be either trilobed or simple oval, and is slightly asymmetrical. The asymmetry of the seedwing makes it spin as it falls, improving wind dispersal. The shape of the wing is important in the identification of different hornbeam species. Typically, 10-30 seeds are on each seed catkin.
Hornbeams yield a very hard timber, giving rise to the name "ironwood". Dried heartwood billets are nearly white and are suitable for decorative use. For general carpentry, hornbeam is rarely used, partly due to the difficulty of working it. The wood is used to construct carving boards, tool handles, handplane soles, coach wheels, piano actions, shoe lasts, and other products where a very tough, hard wood is required. The wood can also be used as gear pegs in simple machines, including traditional windmills. It is sometimes coppiced to provide hardwood poles. It is also used in parquet flooring and for making chess pieces.
^Dai, Jing; Sun, Bainian; Xie, Sanping; Lin, Zhicheng; Wu, Jingyu; Dao, Kequn (2013). "A new species of Carpinus (Betulaceae) from the Pliocene of Yunnan Province, China". Plant Systematics and Evolution. 299 (3): 643-658. doi:10.1007/s00606-012-0750-1.