The genus Cyperus s.l. (950 species) is one of the largest genera in the Cyperaceae. The most obvious diagnostic characteristic is the presence of spikelets with distichous glumes. As is the case for many giant genera, the taxonomic relationships in Cyperus s.l. are still for a large part unclear. However, within Cyperus s.l. several groups can be distinguished morphologically. Many of these groups were placed in separate (sub)genera. According to the first phylogenetic analyses based on markers from the chloroplast genome these groups are nevertheless nested in Cyperus s.s.

Globally seen, the genus Cyperus falls apart in two groups, namely the C3 group and the C4 clade. Each group is characterised by its own photosynthesis type, which is linked to the anatomy type.

The C3 group includes about 150 species. The majority are strong perennial plants of permanently wet habitats such as forest trails and marshes. They are characterised by spikelets, which are grouped in digitate clusters. The C3 photosynthesis type forms the plesiomorphic situation within the genus Cyperus. The origin of the C4 clade from a C3 ancestor and the possible preadaptations have yet to be studied. Several small (sub)genera (Kyllingiella, Oxycaryum, Anosporum, Courtoisina and Androtrichum) are nested in the C3 group. Their exact position in the C3 group and their mutual relationships are still unknown. In this study the molecular 'backbone' of Cyperus senso lato will be reconstructed in collaboration with Marc Reynders, Wim Huygh (UGent) and A. Muthama Muasya (University of Cape Town). The emphasis of this PhD study will be put on the C3 species and (sub)genera and also on the origin of the C4 clade from a C3 ancestor (monophyletic vs. paraphyletic character of the C3 group).

Several African C3 sections include species clusters with a particularly complicated taxonomy. Often, herbarium material of species from these sections was incorrectly identified. The latter is a result of the fact that most identification keys that treat these groups do not function properly because of an overlap in the used characters. Different studies report the necessity of an urgent revision of these groups. One of the aims of this study will be to establish a descriptive and phylogenetic taxonomic revision of the entire Cyperus C3 group. One by one, the various sections and (sub)genera will be tackled. Primarily, the African sections and species clusters with unresolved taxonomic relationships (like the Haspani and the Diffusi) will be studied in detail. This will be achieved using a multi-method approach by incorporating (micro)morphologic, molecular, anatomic, biogeographic and other data. However, the emphasis will be on the molecular part of the study. The assembled information will be integrated in an interactive online database.