Systematics Section / ASPT
Shultz, Leila M. .
Artemisia Subgenus Tridentatae: how many species of sagebrush are there?
Artemisia, with approximately 450 species, is a large and phylogenetically complex group. A particularly vexing problem is the circumscription of 'natural' subgeneric groups within genus, including whether or not to subsume other genera in the Artemisiinae alliance. As traditionally defined, members of Artemisia Subgenus Tridentatae McArthur have homogamous flowering heads with bisexual discoid florets, constituting about 20 taxa. While this is a small subset of the genus, it comprises a group of species with more biomass and occupying more land surface than any other group of shrubs in North America,¬†making the group of particular interest. ¬†Recent molecular phylogenies (Watson et al. 2002, Valles et al. 2003, Riggins and Seigler 2006) call the traditional circumscription of what we call 'sagebrush' into question. These phylogenies suggest that homogamous, discoid capitula may have arisen more than once within the subtribe Artemisiinae of the Anthemideae, and that several species with heterogamous capitula could be included within the Subgenus Tridentatae. Based on structural as well as other chemical similarities, I propose the inclusion of Artemisia filifolia, A. californica, and A. nesiotica in the subgenus Tridentatae. The genus Sphaeromeria may also be part of this clade.
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Flora of North America treatment
1 - Utah State University, Department of Wildlife Resources, Floristics Lab, Old Main Hill 5230, Logan, UT, 84322-5230, USA
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM