ROBERTS, ROLAND P.* AND LOWELL E. URBATSCH. Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803. - Phylogenetic investigations of the Ericameria complex (Astereae, Asteraceae).
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