XVI International Botanical Congess

The high Andes support a unique flora of high endemism. Certain elements of the Andean flora appear to have evolved in situ from lowland ancestors, while other elements dispersed to the páramo from cool regions elsewhere. It has been debated whether the principle mode of evolution of tropical alpine floras is vertical, i.e. gradual evolution from lowland ancestors, or horizontal, i.e. via long distance dispersal from similar habitats elsewhere. The arborescent Polylepis (Rosaceae) is a keystone element in the páramo vegetation. The relations of Polylepis to other genera of the tribe Sanguisorbeae is largely unknown. Among its putative close relatives are Holarctic as well as southern hemispheric taxa. A phylogenetic analysis based on cpDNA was conducted with the aim to estimate the biogeographic history of the Sanguisorbeae with emphasis on the origin of Polylepis.