The Ipomopsis aggregata complex is a group of perennial herbs common throughout western North America. The number of species recognized in the literature has varied from one to ten, indicating considerable taxonomic confusion. Morphological variation in this complex strongly suggests that species are in the process of arising. Therefore, the complex not only requires taxonomic revision but also affords an excellent model for the study of species formation. Data from chloroplast DNA variation will be used to construct a phylogeny of the complex and related species. In addition, data from starch gel electrophoresis of enzymes will be used to assess genetic relationships and levels of gene flow among populations. Results from this study should provide a classification which reflects evolutionary relationships of taxa. It will also be possible to test different hypotheses about the mechanisms which have given rise to these taxa.
