Date of Award

January 2015

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Ronald L. Jones

Department Affiliation

Biological Sciences

Second Advisor

Darrin L. Smith

Department Affiliation

Chemistry

Third Advisor

Patrick J. Calie

Department Affiliation

Biological Sciences

Abstract

This study involved a detailed study of the genus Taxus in Kentucky. A thorough examination was conducted, including a review of the literature, examination of field and herbarium specimens from both native and non-native species, microscopic analysis of leaf ultrastructure, chemical analysis of taxane content, and the construction of GIS models to predict the occurrence of the native species. In the review and examination of morphological features, it was found that the best features for separation of the taxa were plant height, the number of the rows of stomata per abaxial leaf band, and the location of papillose cells on the leaf epidermis. In particular, the SEM studies showed that stomatal bands are a reliable way of differentiating native and non-native Taxus species within Kentucky. A key to the taxa was prepared, as well as descriptions of the species. The chemical analysis failed to uncover any reliable differences between taxa utilizing only five taxanes. GIS models were prepared for 13 counties in eastern Kentucky, and these predicted the most likely occurrence of Taxus canadensis in each portion of the county. This study documented three species of Taxus that occur in Kentucky, T. baccata, T. canadensis, and T. cuspidata. Taxus canadensis is the only native species, considered to be a glacial relict, and is currently listed as a state threatened species. The other two species occur only rarely in nature as escapes from cultivation, likely from the spread of seeds by birds. There is no evidence of hybridization between native and non-native species. It was concluded that microhabitat requirements for T. canadensis are very restrictive, and that ongoing climate change may impact Kentucky's native population of T. canadensis.

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