Birch is the name of any tree of the genus Betula (Bé-tu-la), in the family Betulaceae, closely related to the beech/oak family, Fagaceae. These are generally small to medium-size trees or shrubs, mostly of northern temperate climates. The simple leaves may be toothed or lobed. The fruit is a small samara, although the wings may be obscure in some species. They differ from the alders (Alnus, the other genus in the family) in that the female catkins are not woody and disintegrate at maturity, falling apart to release the seeds, unlike the woody cone-like female alder catkins.
The common name birch is derived from an old Germanic root similar to birka. The Proto-Germanic rune berkanan is named after the birch. The botanic name Betula is from the original Latin. Birch is used as a food plant by the larvae of a large number of Lepidoptera species, see List of Lepidoptera which feed on Birches.
The birch is considered a national tree of Russia, where it used to be worshipped as a goddess during the Green Week in early June.