Abstract: A molecular phylogenetic analysis of the majority of the species of Perezia reveals that, as traditionally defined, the genus is not monophyletic with two (one) species more closely related to Nassauvia than to Perezia. In addition, our results show that Burkartia (Perezia) lanigera is related to Acourtia and is the only member of that clade in South America. The remaining species are monophyletic and show a pattern of an early split between a western temperate and an eastern subtropical clade of species. Within the western clade, the phylogeny indicates a pattern of diversification that proceeded from southern, comparatively low elevation habitats to southern high elevation habitats, and ultimately into more northern high elevation habitats. The most derived clades are found in the high central Andes where significant radiation has occurred.

Key words: Andes, biogeography, Mutisieae, Nassauviinae, Perezia