The hornbeams (Carpinus) are a genus of relatively small hardwood trees, placed in the birch family Betulaceae, though some botanists separate it off together with the hazels (Corylus) and hop-hornbeams (Ostrya) into a segregate family Corylaceae. The 30-40 species occur across much of the north temperate regions, with the greatest number of species in east Asia, particularly China. Only two species occur in Europe, and only one in eastern North America.