The Collaborative International Dictionary of English v.0.48:

Betulaceae \Betulaceae\ n.
   1. a natural family of monoecious trees and shrubs, including
      the genera Betula; Alnus; Carpinus; Corylus;
      Ostrya; and Ostryopsis.

   Syn: family Betulaceae, birch family.
        [WordNet 1.5]