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Molecular phylogenetic reconstructions have indicated that Haworthiais not monophyletic. Here we show, using considerably expanded datasets of both chloroplast (trnL-trnFand psbA-trnHintergenic spacers) and nuclear (ITS1) markers that the issue of a polyphyletic Haworthiais more complicated than previously reported. Both parsimony and bayesian analyses of cpDNA and ITS1 produced poorly resolved phylogenies, with little or no support for deeper nodes. Species of Haworthiaare placed in three of the four main lineages in the cpDNA phylogeny, while in the ITS1 phylogeny Haworthiaspecies were placed in two of the four main lineages retrieved. The cpDNA phylogeny was incongruent with that obtained from the ITS1 data, and the topology of the combined dataset reflected that obtained from the ITS1 dataset. As species of H. subg. Hexangularesand subg. Robustipedunculareshave been reportedly involved in intergeneric hybridizations with other Alooideae, it is postulated that a history of ancient hybridization may account for a polyphyletic Haworthia. Hybridization is also ongoing between species within H. subg. Haworthia, and may be responsible for results indicating that some species in this subgenus are not monophyletic. This hybridization may be facilitated by the lack of effective reproductive barriers. We hypothesize that Haworthiais undergoing a contemporary and explosive radiation in southern Africa, driven in part by local adaptation to relatively fine-grained ecological heterogeneity of soils and microclimate.

The genus Kniphofia, comprising 71 species, has an African­Malagasy distribution, with one species from Yemen. The genus is found predominantly in moist temperate montane grassland and has its centre of diversity in the Drakensberg region of southern Africa. The genus has a complex alpha taxonomy and species relationships are poorly understood. Using a multiple exemplar approach, DNA sequence data from the chloroplast trnT­Lspacer and the nuclear internal transcribed spacer region were used in an attempt to resolve phylogenetic relationships. Five cpDNA lineages were recovered, the geographic distributions of which correspond well with previously identified Afromontane centres of diversity and endemism. The data revealed that several morphospecies were non­monophyletic, and this, together with short branch lengths and many identical sequences within each of the five lineages, suggests a recent radiation. We additionally propose that hybridisation and/ or incomplete lineage sorting may also account for this result. The nrITS region was largely uninformative as many taxa and samples had identical sequences. We hypothesise that Kniphofiaexperienced periods of range expansion, secondary contact and hybridisation during Pleistocene glacial periods, followed by contraction, fragmentation and isolation in montane refugia during the warmer interglacial periods.