A systematic study of the flowering plant genus Micranthes (Saxifragaceae) in the southern Appalachians
- WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
- Max Stovall Lanning (Creator)
- Institution
- Western Carolina University (WCU )
- Web Site: http://library.wcu.edu/
- Advisor
- Katherine Mathews
Abstract: Recent molecular phylogenetic analyses have clearly shown the large, arctic and northtemperate
genus Saxifraga (Saxifragaceae) sensu lato is polyphyletic with two distinct
clades: Saxifraga sensu stricto and Micranthes. Six species belonging to Micranthes
exist in the Southern Appalachians, including two questionably distinct species and one
rock outcrop endemic. Taxonomists have traditionally distinguished the very similar M.
careyana and M. caroliniana primarily based on geographic locality and four
morphological characters: sepal orientation (erect or reflexed), filament shape (uniform
or club-shaped), petal coloration (none or 2 yellow spots), and fruit length (2.5-5 or 4-5
mm). The goal of this research was to examine these characters to clarify the taxonomy
of these species and look for molecular differences in the nuclear and chloroplast DNA
regions, and examine the phylogeny of all six Southern Appalachian species in the
context of the entire genus. Several populations of M. careyana and M. caroliniana
from the Blue Ridge Physiographic Province have been examined and material has been
collected for molecular analyses. Populations in the counties of Ashe, Alleghany, and Watauga (North Carolina) and Johnson (Tennessee) displayed reflexed sepals and clubshaped
stamen filaments, consistent with M. caroliniana. Populations examined in
flower in all other counties displayed erect sepals and uniform stamen filaments,
consistent with M. careyana. The other two characters were not useful in distinguishing
these taxa. These differences in floral characters are correlated with mutations in ITS and
trnL-F sequences. In phylogenetic analyses, populations determined to represent M.
caroliniana appear in a distinct clade from those determined to represent M. careyana,
supporting the separation of the two as species. In addition, the high-elevation rock
outcrop endemic M. petiolaris appears in a distinct clade from the other five Southern
Appalachian species, indicating this taxon evolved along a separate lineage and should be
placed in the genus Hydatica in future systematic treatments.
A systematic study of the flowering plant genus Micranthes (Saxifragaceae) in the southern Appalachians
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Created on 12/1/2009
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Additional Information
- Publication
- Thesis
- Language: English
- Date: 2009
- Keywords
- Biogeography, Micranthes, Plant systematics, Southern Appalachians, Species concepts
- Subjects
- Saxifraga -- Appalachian Region, Southern