Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2005. / The family Oxalidaceae has a worldwide distribution, but is most common in tropical and subtropical regions. Oxalis L. is the largest genus of the family comprising ca. 800 of the 900 species. Oxalis species are annual or perennial herbs or rarely subshrubs or trees. The current study assesses on the taxonomic placement of O. furcillata Salter. Currently this species, comprising two varieties, O. furcillata var. furcillata and O. furcillata var. caulescens Salter, is placed in section Foveolatae. Members of this section have endospermous seeds and fleshy leaflets. However, both in terms of leaf morphological and seed characters the two varieties of this species appear to be misplaced within this section. In addition O. furcillata var. caulescens has a unique pollen type, different from both the typical variety and the rest of the section. Both lines of evidence thus suggest that O. furcillata var. caulescens may be misplaced within this section. The present study thus sets out to assess the placement of O. furcillata in general, and the placement of O. furcillata var. caulescens in particular. A multi-disciplinary approach was followed, which included analyses of macro-morphological (including LM and SEM analyses), biogeographical and palynological characters. The variability of quantitative characters was assessed using the STATISTICA 6.0 software package. Leaf dimensions, plant height, bulb length, petiole length and palynology showed sufficient differences between the two taxa to confirm the separate identity of these two varieties as separate species. O. furcillata var. caulescens was thus raised to specific status as O. caulescens (Salter) Bissiengou. The results suggest two different options in terms of the taxonomic placement of the species O. furcillata and O. caulescens. They can either remain in section Foveolatae, best placed near O. senecta and O. densa or may moved to the highly variable section Latifoliolatae. But retaining them within the section Foveolatae appeared to be the better alternative. The correct position will be established both through further morphological analyses and correlation to the trnL-F and ITS sequence-based phylogeny of the southern African members of Oxalis.

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.