XVI International Botanical Congess

Abstract: The Sect Wyomingia of Erigeron comprises 10 species and is distributed throughout the Southwestern US, from Wyoming to New Mexico to California. They are taprooted perennials with linear leaves, a strigillose vestiture of short, closely appressed hairs, erect buds, and prominently coiling ligules. Nesom's 1989 treatment recognized two groups within the section, the E. compactus group (E. carringtonae, E. compactus, E. consimilis, E. nematophyllus, E. untermanii) with multi-nerved achenes and the E. pulcherrimus group (E. argentatus, E. canus, E. parishii, E. pulcherrimus, E. utahensis), with unadorned achenes. Sequences of ITS1 and ITS2 regions of 18S-26S ribosomal DNA were determined. Preliminary phylogenetic analysis provides strong support for a taxonomic realignment, indicating that separation of the two groups based on achenial nerves may be largely artificial.