Systematics of Trichostema (Lamiaceae): Evidence from ITS, ndhF, and Morphology
Trichostema (Lamiaceae) is a North American genus comprising five sections and 18 species. Phylogenetic relationships were inferred using DNA sequences (ITS, ndhF) and morphology (63 characters). The monophyly of Trichostema is well supported in four analyses (ITS,
ndhF, ITS + ndhF, ITS + ndhF + morphology), but not in the analysis based on morphological data alone. In all analyses, the monophyly of sections Chromocephalum and Trichostema is well supported. The monophyly of section Paniculatum is moderately supported,
and there is conflicting evidence regarding the monophyly of section Orthopodium. Although DNA data alone suggest that T. brachiatum is not a member of section Orthopodium, its retention in section Orthopodium is equivocal in the combined DNA-morphology analyses.
The submerging of the monotypic section Rhodanthum into Paniculatum by Lewis and Rzedowski is not adopted because the monophyly of this grouping is poorly supported. Biogeographic history and character evolution (life history and chromosome number) are explored in the context
of the phylogeny based on the combined ITS and ndhF sequence data.
Keywords: BIOGEOGRAPHY; CHARACTER EVOLUTION; LAMIACEAE; MOLECULAR PHYLOGENY; TRICHOSTEMA
Document Type: Research Article
Publication date: 01 April 2008
- Systematic Botany is the scientific journal of the American Society of Plant Taxonomists and publishes four issues per year.
2011 Impact Factor: 1.517
2011 ISI Journal Citation Reports® Rankings: 87/190 - Plant Sciences
34/45 - Evolutionary Biology - Editorial Board
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