including the Angiosperm Phylogeny Group, have described these two groups as subfamilies within an expanded Betulaceae: Betuloideae and Coryloideae.

Betulaceae flowers are monoecious, meaning that they have both male and female flowers on the same tree. Their flowers present as catkins and are small and inconspicuous, often with reduced perianth parts. These flowers have large feathery stamen and produce a high