In the division of Centaurium s. lat. into segregate genera in phylogenetic studies by Mansion and Struwe, the more recently described species C. blumbergianum is referable to Gyrandra. The new combination G. blumbergiana is published. A nomenclatural study of North American Lomatogonium indicates that the name L. rotatum was validly published by Fries, and that the only name based on specimens of the taxon native to the interior of western North America is Pleurogyne fontana. In order that this taxon may continue to be treated as an infraspecific taxon within L. rotatum, the new combination L. rotatum var. fontana is published.