Systematic and evolutionary studies of Ericameria based largely on morphological and cytological data have resulted in dramatically different phylogenetic concepts. Ericameria has been treated as a section of Haplopappus and as a distinct genus. At various times, species in the genus Chrysothamnus have been transferred to Ericameria. Additional proposals suggest that all species of Chrysothamnus, and species previously residing in Haplopappus sections Asiris, Macronema, and Stenotopsis be treated as Ericameria. Furthermore, the genus Xylothamnia was established to accommodate certain species that were once part of Ericameria. Inferred relationships based on DNA sequence data from a few representative taxa are not entirely in keeping with existing assumptions but provide the basis for additional hypotheses. For example, Chrysothamnus viscidiflorus forms a clade including Solidago petiolaris and Sericocarpus tortifolius, while Tracyina, Ragiopappus, and Pentachaeta form a clade with a representative species of Ericameria. This study proposes to investigate, in more detail, phylogenetic relationships of this complex using DNA sequence data from both nuclear and chloroplast markers. Preliminary data suggest that the ITS and ETS regions and the 3 trnK intron will provide information useful for phylogenetic reconstruction.

Key words: Asteraceae, Astereae, Chrysothamnus, Ericameria, Phylogeny