The work comprises two principal sections; an attempt at ellucidating generic relationships in the South African bulbous Liliaceae, and a revision of the species of selected genera. In the first section the approaches investigated were: 1) A re-evaluation of the nature of the bulb apex, showing a likelihood that certain groups possess axillary and other groups terminal inflorescences. 2) An investigation of leaf anatomy, showing that most genera have very similar leaf structure, but that a few genera do differ from this norm. Scilla (Euscilla) generally possesses a distinctly lignified bundle sheath and the Urginea-Drimia group show a great range in structures - including a palisade. 3) An impression technique to determine patterns in the surface of the leaf cuticle. A close correlation appears to exist between these patterns and leaf shape. 4) Scanning Electron Microscope pictures of pollen revealed a considerable uniformity within the group and between this group and most other members of the Liliaceae. 5) Scanning Electron Microscope pictures of seeds revealed two main groups in the bulbous Liliaceae determined on the appearance of the cell walls of the testa. 6) A simple chromatographic technique was not found to be useful. 7) An investigation of chromosome numbers of. 44 samples of 15 species supplemented published data in allowing an analysis to be made of the application of chromosome numbers to generic concepts. Many genera of the Liliaceae - especially in the bulbous group - have extremely variable chromosome numbers. It is considered that numbers are more applicable to tribal than to generic concepts. Few indications of meiotic abnormalities were detected. Phylogenetic and taxonomic aspects of the genera of the bulbous Liliaceae are discussed and a key to the South African bulbous Liliaceae genera constructed. The following generic alterations are proposed: Ledebouria to be split off Scilla. Schizocarphus to be placed in Scilla. Resnova to be placed in Drimiopsis. The Astemme section (= Neobakeria) to be removed from Polyxena and placed in Massonia. The Cape species of Hyacinthus to be placed in Polyxena. Thuranthos, Urgineopsis and Urginea to be placed in Drimia. It is suggested that Schizobasis and Bowiea are of great importance in explaining the origin of Asparagus - possibly even directly from this group. In the generic revisions, thirteen genera are dealt with including typification, synonymy, distribution, field notes, species descriptions and keys. 67 species are dealt with, of which three are new (all in Ledebouria), and 31 new combinations are proposed.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:rhodes/vital:4261 |
| Date | January 1973 |
| Creators | Jessop, John Peter |
| Publisher | Rhodes University, Faculty of Science, Botany |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Doctoral, PhD |
| Format | 306, 168 leaves, pdf |
| Rights | Jessop, John Peter |
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