‘n Morfologiese Studie van die Genus Ficus L. In Suidelike Afrika

Abstract

Previous research on the genus Ficus L. was mainly taxonomical and based on organographic characteristics. From this investigation it is clear that the delimitation of certain taxa is unsatisfactory because research was based on herbarium specimens which often were incomplete and represented extreme variants within species. Consequently, the purpose of this investigation was to find additional criteria on the basis of which the delimitation of the Southern African taxa could be revised. In the investigation, herbarium specimens were used as well as fresh and fixed material which was collected by the candidate in different localities. The following aspects were investigated:1. Organography, including the morphology of syconia and flowers.2. Anatomy of leaves, stems, wood, syconia and drupes.3. Pollen morphology.4. Numerical taxonomy.5. Chemotaxonomy.6. Distribution Results It was found that the position where syconia are borne, the arrangement of ostiolar hypsophylls and the position of male flowers insidesyconia, are the most important organographic characteristics for the identification of taxa. A key was compiled by means of which During this investigation it was found that leaf anatomy, especially the number of epidermal layers, location of cystoliths and appearance of the spongy mesophyll are useful characteristics for the identification of species and the delimitation of taxonomic with the aid of a key based on anatomical characteristics of leaves, all species with the exception of F. polita and Fosansibarica can be identified. The anatomy of the stems, wood and syconia of the investigated species are so similar that it cannot be used for interspecific delimitation. The morphology of the pollen differs very little between species. The small, smooth, bi- or triporate pollen grains indicate that the genus is derived from wind pollinated ancestors. Due to the complicated pollination biology, the genus is considered to be the most advanced of the Moraceae. Numerical and chemotaxonomical methods provided information which supports the results of a morphological investigation. In this investigation a comparison of the flavonoids in the plants did no tyield significant results. On the other hand, a comparison of organographic and anatomical characteristics by means of numerical taxonomical methods proved valuable in the delimitation of subgenera and series. From a survey of the distribution and habitat of Southern-African Ficus-species, it appears that the more primitive taxa such as thesubgenus Sycidium, has a northern distribution, especially in marshyhabitatso Representatives of an advanced taxon such as the series Axillares on the other hand, has a southern distribution in morearid areas.Except for F. sycomorus, F. salicifolia, F. fischeri, F. ilicina,F. tettensis, F. trichopoda and F. vogelii of which the synonymyhas already been dealt with by other authors and which is supportedby this investigation, it is recommended that F. petersii be sunk under F. burkei and F. sonderi under F. glumosa.