Repeated hybridizations and/or polyploidizations confound taxonomic classification and phylogenetic inference, and multiple colonizations at different time scales complicate biogeographic reconstructions. Pimentel et al. sequence three plastid and two nuclear DNA regions in 17 Anthoxanthum taxa in order to unravel the role of these processes in shaping the current structure and diversity of the genus. Variation of floral morphology in Anthoxanthum (sections Anthoxanthum and Ataxia) can be explained by a Miocenic hybridization event between lineages with one and three fertile florets. All diversification events in the genus except one are dated back to between the Late Pliocene and the Late Pleistocene. Africa was apparently colonized twice from two different sources, namely Europe and East Asia.