BETULACEAE - Birch Family

Deciduous trees and shrubs

Leaves alternate, simple, with stipules

Flowers unisexual, highly reduced, in catkins, wind-pollinated

Fruit a 1-seeded samara or nut

6 genera, 120 species

Economic importance - timber from birches, hazel nuts

Diagnostic characters - deciduous trees or shrubs, leaves serrate, staminate flowers in catkins, pistillate flowers in coneline catkins

Unusual charcteristics - Alnus (alders) fix nitrogen in nodules on roots