Species of Mimulus are important models for the study of plant evolution, population biology, and genetics. However, the phylogenetic relationships among species of Mimulus are not clear, nor is the relationship of Mimulus to other genera in the tribe Mimuleae or the position of this group to other families of Lamiales. The monophyly of the tribe and the seven major sections within Mimulus were tested using sequences of the nuclear ITS and ETS regions and the chloroplast leucine tRNA (trnL) intron and the intergenic spacer between trnL and trnF. Data from over 110 taxa indicate that the genera Leucocarpus, Hemichaena, Berendtia, Lancea, and the taxonomically isolated Phryma are derived from within Mimulus. The Australian genera Glossostigma and Peplidium are also derived from within Mimulus, indicating a second regional diversification of Mimulus in Australia (ca. 20 species), in addition to the recognized diversification in western North America. Within Mimulus, sections Diplacus, Erythranthe (plus M. parishii), and Simiolus (minus M. gemmiparus) are monophyletic. Sections Mimulus, Eunanus, Oenoe, Paradanthus, and Mimulastrum are paraphyletic.

Key words: Lamiales, Mimuleae, Mimulus, Phryma