Treatments vary as to synonymy under Cyperus. Sometimes Pycreus and Kyllinga are placed in synonymy as well as Mariscus and Juncellus. We include Mariscus and Juncellus for the present and maintain Pycreus. Phylogenetic studies have shown that Cyperus is polyphyletic and it is possible for genus circumscriptions to change in the future.
Isabel Larridon (Gent University, Belgium) is working on Cyperus sect. Diffusi (including species such as C. baronii, C. balfourii, C. longifolius) as part of her PhD study. She has reported numerous problems with species circumscriptions.