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Systematics Section / ASPT

Williams, Justin [1].

A Morphometric Analysis of the Amsonia tabernaemontana Walt. Complex (Apocynaceae).

The Amsonia tabernaemontana Walt. complex is comprised of six weakly defined species distributed throughout the Southeastern United States. The majority of these species have been distinguished mostly by the presence and distribution of hairs (ex. glabrous vs. pubescent corollas, densely vs. sparsely pubescent leaves) and by the leaf dimensions. Traditionally these taxa have been difficult to discern from one another and much confusion has resulted as to the correct identification of species within the complex. In order to better delineate the taxa within the genus, specimens throughout the range of the complex were examined. Seven morphological metrics of potential and assumed taxonomic significance were identified. Selected herbarium specimens with all seven quantitative characters intact were measured. The measurements were entered into a database and a principal component analysis was performed. Results indicate that the majority of species are not statistically variable in floral characters or in leaf dimensions. Rather the variation amongst taxa appears to represent a geographic gradient indicating that many of the species described represent extreme variants rather than independent species.

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1 - Sam Houston State University, Department of Biological Sciences, Box 2116, Huntsville, Texas, 77341-2116, USA


Presentation Type: Poster
Session: 33-100
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM
Abstract ID:227

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