Betulaceae S.F. Gray.
A family of 6 genera and about 150 species, primarily of subarctic to cold temperate regions of the Northern Hemisphere, but extending through Central America to n. South America. The two subfamilies recognized here are sometimes elevated to family status (Betulaceae s.s., including Betula and Alnus, and Corylaceae, including Corylus, Carpinus, and Ostrya in our region), as by Govaerts & Frodin (1998), an approach which is certainly defensible based on morphological and phylogenetic evidence (Yang et al. 2019).
Ref: Furlow (1990); Furlow (1997) In Flora of North America Editorial Committee (1997); Govaerts & Frodin (1998); Hardin (1971a); Kubitzki, Rohwer, & Bittrich (1993); Yang et al. (2019). Show full citations.