D.Phil. / The genus Crotalaria (tribe Crotalarieae, Fabaceae) includes 700 species with its main centre of species diversity in Africa and Madagascar and secondary radiations to other parts of the world (including North and South America, India, South-East Asia and Australia). Molecular systematics has recently provided profound new insights into generic relationships in the Crotalarieae, thereby creating the opportunity to re-evaluate the taxonomic and functional significance of flower and fruit structure in the tribe, with emphasis on the large genus Crotalaria. A representative sample of flowers from 211 species was dissected to record morphological character states and fruit transverse sections of 142 species was cut to record anatomical variation across the tribe. These data were supplemented from the literature to allow for generalizations. Six structural-functional flower types were identified: (1) pump; (2) gullet; (3) hugging; (4) saddle; (5) tunnel; and (6) brush. The saddle and tunnel types are here described for the first time. Crotalaria is the only genus within the tribe that has the brush type; specialized flowers characterized by a rostrate keel, highly dimorphic anthers, stylar trichomes and four types of elaborate callosities on the standard petal: (1) ridge callosities – vertical swellings on the blade and claw; (2) disc callosities – subcircular swellings on the blade; (3) columnar callosities – cylindrical protruding appendages on the blade; and (4) lamelliform callosities – plate-like protruding appendages on the blade. Trends toward specialization are apparent across the phylogeny as a whole suite of specialized floral characters and are homoplastic as a result of convergence.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:9395 |
| Date | 15 August 2012 |
| Creators | Le Roux, Margaretha Marianne |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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