Systematic applications of pollen grain morphology and development in the acanthaceae
Date
2016
Authors
House, Alisoun Valentine
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Abstract
External pollen grain morphology has been widely used in the taxonomy and
systematics of flowering plants. The eurypalynous family Acanthaceae is a notable
example of a group where these pollen diversities have proved useful in determining
relationships between taxa. However, internal pollen wall features have received far less
attention due to the difficulty of examining the underlying exine from which the
external sculpturing is derived. Consequently, internal wall features have thus far not
been used in formulating existing classifications. A new technique involving precise
cross sectioning or slicing of pollen grains at a selected position, using a focused ion
beam-scanning electron microscope (FIB-SEM), was used on 39 species of
Acanthaceae to examine the internal pollen wall structure and identify features of
potential systematic relevance. Five basic internal wall structures were described in this
study. The study also showed that similar external pollen wall features may have
distinctly different underlying structures.
Description
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015.