We examined the phylogenetic relationships and patterns of character evolution among the California poppies and their relatives (Papaveraceae, Eschscholtzieae) using morphological comparisons and parsimony and likelihood-based phylogenetic analyses of two chloroplast and two nuclear DNA regions, including 14-3-3-like, a phylogenetically informative nuclear DNA region developed for this research. Each of the three genera in the tribe (Dendromecon, Eschscholzia, and Hunnemannia) is strongly supported as monophyletic, but not all species of Eschscholzia display monophyly based on molecular data. Examination of biogeographic patterns indicates that dispersal to island habitats occurred more than twice in the tribe. Phylogenetic reconstruction of the evolution of chromosome number suggests that there were several polyploidy events within the tribe and likely one or more aneuploid events within Eschscholzia. Based on the results presented here, the subspecies of both Eschscholzia californica and Eschscholzia lemmonii will be promoted to specific status. Additionally, the study provides evidence supporting recognition of two new species of desert Eschscholzia.