D.Phil. (Botany) / A taxonomic revision of the genus Centella is presented that is based on vegetative and reproductive characters. Genetic data was included in the extensive research ofpossible hybridisation. Hybridization as a possible mechanism of evolution may account for the lack of conguence between taxonomic characters in Centella. Phylogenetic and phenetic methods of analysis were used to explore the relationships among species. The results show that Centella is a particularly difficult genus, with many ofthe problems experienced at species level being a reflection ofthe problematic nature of the Apiaceae. The taxonomic treatment includes nomenclature, synonymy, typification, diagnostic characters, detailed illustrations and geographical distribution of all 45 species that are recognized. Keys to the subgenera, sections and species are provided. The revision includes several taxonomic and nomenclatural changes. The genus is subdivided as follows: Subgenus Trisanthus Subgenus Solandra Subgenus Centella 1 species 4 species Section Erianthae Section Tri/obae Section Centella Section Virgatae 9 species 3 species 16 species 12 species The following 13 new species were described: C. annua, C. calcaria, C. rotundifolia, C. umbellata, C. ternata, C. crenata, C. cryptocarpa, C. gymnocarpa, C. pi/osa, C. brachycarpa, C. dolichocarpa, C. thesioides and C. glauca. One ofthese species C. cryptocarpa, has been collected for the first time. Centalla rotundifolia, C. cordata and C. longifolia were elevated to species rank and C. rigescens was reinstated as a species of Centella. The number of varieties was significantly reduced and variation within the species is mostly described informally. Varieties were retained for only two species. New varieties are: C. tridentata var. tridentata, C. tridentata var. littoralis, C. tridentata var. hermanniifolia, C. tridentata var. dregeana, C. graminifolia var. graminifolia, C.graminifolia var. natalensis and C. graminifolia var. stipitata.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:11322 |
| Date | 02 June 2014 |
| Creators | Schubert, Mahalia Theresia Reina |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
Page generated in 0.0016 seconds