Birch is the name of any tree of the genus Betula in the family Betulaceae, closely related to the beech/oak family, Fagaceae
Birch species are generally small to medium-size trees or shrubs, mostly of temperate climates. The simple leaves may be toothed or pointed. The fruit is a small samara, although the wings may be obscure in some species. They differ from the alders (Alnus, 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 bark of all birches is characteristically marked with long horizontal lenticels, and often separates into thin papery plates, especially upon the Paper Birch. It is practically imperishable, due to the resinous oil which it contains. Its decided color gives the common names Red, White, Black, Silver and Yellow to different species.
