Many diverse plant clades possess bilaterally symmetrical flowers and specialized pollination syndromes suggesting these traits may promote diversification. We examine the evolution of diverse floral morphologies and the association with diversification history in a species-rich tropical radiation of Rhododendron. We used restriction-site associated DNA sequencing on 114 taxa from Rhododendron sect. Schistanthe to reconstruct phylogenetic relationships, infer colonization of Southeast Asia and examine hybridization. We then captured and quantified floral variation using geometric morphometric analyses...