The origins of Eleocharis (Cyperaceae) and the status of Websteria , Egleria , and Chillania

Eleocharis R. Br. is an ecologically and economically important genus that contains about 250 species of annual and perennial sedges, with centers of diversity in seasonally wet tropical to subtropical regions. Phylogenetic relationships in the genus are poorly understood, particularly in relation to three monotypic genera— Egleria L.T. Eiten, Chillania Roivainen, and Websteria (Poir.) S. Hooper—which have been variously included or excluded from Eleocharis in different classifications. These genera, while morphologically distinct, show characteristics that fall within the range of variation seen in Eleocharis . The relationship between the clade containing Eleocharis and these segregate genera (i.e., Eleocharideae) and the rest of Cyperaceae has also been difficult to determine from previous studies, and numerous conflicting hypotheses have been suggested. To address these uncertainties, we sequenced cpDNA from the ndhF and psbB-psbH marker regions and used it to reconstruct the phylogenetic history of Eleocharis and a broad sample of other Cyperaceae. We found that Egleria and Websteria are derived from within Eleocharis , and that this clade, representing the Eleocharideae, is sister to the Abildgaardieae. Chillania could not be included in the molecular dataset, but its morphology suggests it should be included in Eleocharis . New nomenclature is suggested to place the species of Chillania, Egleria , and Websteria in Eleocharis . Our phylogenetic reconstructions also indicate several other instances of generic paraphyly in other Cyperaceae lineages.