Master's Theses

Date of Award

Spring 2008

Degree Name

Master of Science (MS)

Department

Biology

Advisor

Joseph Thomasson

Abstract

Previous studies of Ulmus pumila Linnaeus and Ulmus rubra Muhlenberg and their hybrid Ulmus x notha Wilhelm and G. Ware were restricted mainly to investigations of Dutch elm disease resistance/breeding for the cultivar trade. Recent studies have focused on and distribution and descriptions of phenotypic characters of these taxa. Ulmus pumila L. and U. rubra Muhl. And their hybrid U. x notha Wilh. G. Ware were studied at two sites in Kansas; the Comeau Ranch, north central Ellis County and Spring Creek at the western end of Wilson Reservoir, Russell County. Specimens from 12 U. pumila, 16 U. rubra, and 38 U. x notha specimens were sampled at four yearly stages (leafing, winter twig, flowering, and fruiting) for comparative studies of morphological features. Twenty-one features were measured/counted and used to create morphological keys and species descriptions. Leaves were measured for length, width, and basal asymmetry. Primary teeth of the leaves were measured for length, depth, and breadth and the number of primary and secondary teeth were counted. Flower buds were measured for length, width, and length/width ratio. Flower stamens and sepals were counted and stigma color was determined. Shape and surface features of the pollen was documented. Finally, fruits were measured for length, width, length/width ratio, and basal asymmetry. Data showed U. pumila and U. rubra scores separated each species completely, while U. x notha scores were intermediate to the parental scores. Ulmus x notha upper scores for morphological features of the leaf, flower bud, and flower overlapped with the lower scores of U. rubra and lower scores of U. x notha overlapped with the upper scores of U. pumila. Fruit scores and pollen morphology were not useful in separating the three species from each other.

Rights

Copyright 2008 Kurtis J. Cooper

Comments

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