Abstract
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.