Birch's the name of any tree of the genus Betula (Bé-tu-la), in the family Betulaceae, closely related to the beech/oak family, Fagaceae. Description Birch species are generally small to medium-size trees or shrubs, mostly of northern temperate climates. The simple leaves may be toothed or pointed. The fruit's 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 aren't woody and disinte… (More on Birch)