Systematic and evolutionary studies of Ericameria based largely on morphological and cytological data have resulted in numerous, dramatically different, concepts of relationship. 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 sequence data of the internal transcribed spacer (ITS) and external transcribed spacer (ETS) regions of nuclear ribosomal DNA are not entirely in keeping with existing assumptions but provide the basis for additional phylogenetic hypotheses. Species of Chrysothamnus sensu Nesom form a clade that includes Solidago, Sericocarpus, and certain species of Tonestus. Ericameria sensu Nesom forms a clade distinct from that containing Chrysothamnus and is sister to Tracyina, Ragiopappus, and Pentachaeta. Xylothamia, as defined by Nesom, appears to represent at least two different lineages and probably is paraphyletic. Ericameria's subtribal affiliation with Hinterhuberinae is not supported by sequence data.

Key words: Asteraceae, Astereae, Chrysothamnus, Ericameria