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Abstract Detail


Systematics Section / ASPT

Kempton, Elizabeth [1], Columbus, J. Travis [2].

Phylogenetics of the Eriogonum clade (Polygonaceae, Eriogonoideae) based on nuclear and chloroplast sequences.

The Eriogonum clade (Polygonaceae, Eriogonoideae) comprises ca. 325 annual and perennial species distributed in temperate and arid regions of North and South America. Recent studies provide strong support for the Eriogonum clade, although relatively few taxa have been sampled. Twenty genera are currently recognized in the clade, with most species in Eriogonum (ca. 250) or Chorizanthe (ca. 50), and the remaining species segregated into small monotypic or oligotypic genera. A peculiar feature present in Polygonaceae is the ocrea (or stipular sheath); this structure is absent in the Eriogonum clade (vestigial only in some perennial Chorizanthe). Distinct from other Polygonaceae, all members of this clade except Gilmania possess involucral bracts. Variation in the form of these bracts (including arrangement, fusion, or presence of awns) has served to delimit some genera. Goals of this study are to: (1) sample members from all genera and infrageneric groups; (2) use multiple chloroplast and nuclear DNA sequences for phylogenetic analyses; (3) identify morphological and anatomical synapomorphies for clades; (4) examine character evolution (e.g., awns) and biogeography; and (5) as necessary, propose changes to the current classification. Preliminary phylogenetic analyses of chloroplast (trnL–F) and nuclear ribosomal (ITS) sequences, for 50 species representing 15 ingroup genera, strongly support the clade but do not support monophyly of Eriogonum or its subgenera. Several of the smaller genera appear to be early diverging lineages within the clade. It also appears that involucral awns have evolved more than once in the group.


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1 - Rancho Santa Ana Botanic Garden, 1500 N. College Ave, Claremont, CA, 91711, USA
2 - Rancho Santa Ana Botanic Garden, 1500 North College Avenue, Claremont, California, 91711, USA

Keywords:
Polygonaceae
Eriogonoideae
Eriogonum
Chorizanthe
phylogenetics.

Presentation Type: Oral Paper:Papers for Sections
Session: CP42
Location: Boulevard C/Hilton
Date: Wednesday, July 11th, 2007
Time: 10:30 AM
Number: CP42009
Abstract ID:1006


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