Deciduous trees and shrubs. Leaves simple, alternate, mostly toothed or occasionally lobed, stipulate. Male and female flowers separate, but on the same plant, in clusters grouped in 1s or 3s each with an associated bract. Perianth, when present, scale-like and with a variable number of segments. Male flowers in pendulous catkins, each with 2-14 stamens. Female flowers generally erect. Carpels 2, fused and with 2 styles. Ovary inferior and with axile ovule placentation. Pollination is by wind. Fruit a 1-seeded nut or winged samara.
This family is generally considered most closely related to the Fagaceae.
Birches are an important timber in N America together with Alnus, Alder, and Ostrya. The edible hazelnuts (cobnuts and filberts) are obtained from the genus Corylus.
Woody plants; petals absent, male flowers in catkins; 2-3 flowers with each bract; styles 2.
6 genera and about 140 species mostly northern temperate but extending into tropical montane S America, SE Asia and N India.
Source: (1997). Betulaceae. In: . Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.