M.Sc. / A taxonomic revision of the genus Rafnia Thunb. (= Oedmannia Thunb., Vascoa DC., Pelecynthis E. Mey), a relatively poorly known papilionoid legume genus, is presented. Rafnia (family Fabaceae, tribe Crotalarieae) is subendemic to the fynbos region of the Western and Eastern Cape Provinces of South Africa, with one species having a distribution area reaching into KwaZulu-Natal. The species delimitation has been unsatisfactory, and the relationships among the taxa uncertain. Rafnia is divided into two sections and 19 species are recognized, compared with the 22 species previously distinguished by Harvey (1862). There are five new species and four species are subdivided into subspecies, eight of which are described for the first time. There are eight changes of status and one new combination is made. Rafnia constitutes a total of 31 taxa. Morphological data used to investigate relationships among the species of Rafnia are analyzed phenetically and cladistically and keys to the sections, species and subspecies, complete nomenclature, typification, descriptions as well as the geographical distribution for each of the taxa are presented. Proposals are made to resolve troublesome uncertainties regarding the nomenclature and typification of some species. The scope of this study did not permit detailed investigation into chemical or molecular evidence, although preliminary studies showed that such data would improve the understanding of the infrageneric relationships within the genus. Characters and character states show much variation, but an hypothesis of the phylogenetic relationships amongst the taxa is nevertheless presented. An in-depth study of morphological characters in particular has resulted in a better understanding of taxonomic relationships at the generic and infrageneric levels in Rafnia.

M.Sc. / A biosystematic study of the genus Sutherlandia (L.) R. Br., a poorly studied genus with confusing geographical variants, is presented. The species of Sutherlandia are all endemic to southern Africa. The species are very closely related and problems regarding their taxonomy are discussed. A few morphological characters that are useful in distinguishing amongst species are illustrated and discussed in detail. Morphological data are used to investigate infrageneric relationships in a phenetic analysis of 51 geographically separated populations. Sutherlandia has traditional medicinal uses, mainly as an anti-cancer treatment for internal cancers and as a general tonic. A survey of chemical compounds was done and the results are illustrated and presented in tables. The nature of this study did not allow detailed medical investigations, but the medicinal value of Sutherlandia and the compounds detected are highlighted. It is suggested that the anti-cancer activity can mainly be ascribed to the high levels of canavanine, a non-protein amino acid, in the leaves of the plant. Canavanine, an arginine analogue, is known for its antitumourigenic properties. The value of the plant as a bitter tonic is probably related to the presence of several triterpenoids, some of which may well also have other beneficial effects. Enzyme electrophoresis was done to explore genetic relationships amongst the numerous regional forms of Sutherlandia. A study of 19 populations showed that they are all closely related and that a more conservative treatment of the taxa is called for. As a result the number of taxa is reduced. A complete taxonomic revision of the genus is presented. The number of species is reduced from six to two, namely S. frutescens and S. tomentosa. The former is divided into three subspecies, namely subsp. frutescens, subsp. microphylla and subsp. speciosa. Some regional forms are described and illustrated, but these are not formally recognised as taxa. A key to the species, subspecies and regional forms is provided, and the. nomenclature, typification, description and geographical distribution for each of the taxa are given. The multidisciplinary approach of this study provided a better understanding of the morphological, chemical and genetic variation in this relatively poorly known but potentially valuable ornamental and medicinal plant.