Document Type

Thesis

Degree

Master of Science

Major

Biology, Plant Systematics

Date of Defense

7-15-2010

Graduate Advisor

P. F. Stevens, Ph. D.

Committee

Van der Werff, Henk

Keating, Richard

Abstract

The relationship of species of Aiouea (Lauraceae) to Cinnamomum, Ocotea, and Mocinnodaphne was evaluated using leaf epidermal characters. Representative species of these genera had been placed in two quite separate clades in a previous molecular study by Chanderbali et al. (2001). This study includes thirty-seven neotropical species of Aiouea, Cinnamomum, Ocotea and Mocinnodaphne. Epidermal characters, including the stomatal apparatus, were observed to evaluate the relationship of Aiouea with the other three genera. Samples were examined under light microscopy and scanning electron microscopy, and characters were scored from digital images. A stomatal rim made by the cuticle around the stomata was identified in thirty-four species. Principal component analysis and means tests were performed to see whether groups could be distinguished using stomatal variation. Only stomatal rim width was found to distinguish groups. Although the stomatal rim obscures observation of the stomatal apparatus, the species here can be characterized as having anomocytic stomata because subsidiary cells were not distinguishable, highly unusual within the magnoliids as a whole. Three groups were recognized. The first group has a wide stomatal rim and includes all the species of Aiouea from South America, Cinnamomum from central and South America, and Mocinnodaphne; all species of this group also have conspicuous staminodes in the fourth stamen whorl and a thick leaf margin. The second group has a narrow stomatal rim and includes all the species of Aiouea from in Central America and the species of O. insularis group from in Central America and northwest South America; all species also have trichomes on the abaxial side of the third whorl of the stamens and a strictly cymose inflorescence with flattened axes. The third group includes two species (A. guatemalensis and A. inconspicua) without a stomatal rim. These two species are the northern distribution range of Aiouea and lack both the cymose inflorescence and the trichomes in the stamens.

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