The milkweed subfamily of the flowering-plant family Apocynaceae, including more than 214 genera and about 2,400 species. Formerly treated as its own family Asclepiadaceae. However, molecular evidence suggests that the group is evolutionarily derived from Apocynaceae, and thus it has been recategorized as a subfamily by the Angiosperm Phylogeny Group III (APG III) botanical classification system.
