Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2005. / At present a proper systematic classification of the southern African members of Oxalis L.
(Oxalidaceae) does not exist. The most recent and comprehensive revision of the genus based
on macro-morphological characters is out-dated (published 60 years ago (Salter, 1944)). The
external morphology of the flowers of the southern African Oxalis species is reasonably wellstudied,
but little is known about the anatomy thereof. A pilot study of fruit and seed
morphology and anatomy of nine selected southern African Oxalis species (Obone, 2003)
already revealed some trends to demarcate two main groups. This confirmed the systematic
value of some of the characters already proposed by Salter (1944).
The aim of the present study was to assess the potential systematic value of fruit and seed
morphology and anatomy of 32 Oxalis species. The selection was done such that the included
species would represent the main sections proposed by Salter (1944), the pollen types
proposed by Dreyer (1996) and the different clades revealed by the phylogenetic tree
compiled by Oberlander et al. (2004).
Although the species sampling was very low (20% of the southern African taxa), 35
potentially informative characters were identified in fruit and seed morphology and anatomy.
These characters may be grouped into three character types, namely autapomorphic
characters, randomly distributed characters and systematically informative characters. The
first two character types were particularly useful in species-specific characterization. The
third group of linked characters could be used to demarcate two major groups of species,
those producing endospermous seeds and those producing exendospermous seeds. The three
types of characters may prove to be taxonomically informative if more species-inclusive
studies are performed.
The cluster analysis strongly supported the demarcation of endospermous and
exendospermous groups with 100% bootstrap support. Low bootstrap values were observed
for subgroups within each of the major groups. This is probably due to low taxon sampling.
Therefore clustering based on fruit and seed morphology should be considered with extreme
caution within the two groups. Despite these limitations of sample size, fruit and seed
morphological and anatomical characters have proven to be systematically informative at the
infra-generic level.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/3403 |
| Date | 12 1900 |
| Creators | Obone, Charline |
| Contributors | Dreyer, L. L., Marais, E. M., University of Stellenbosch. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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