Cyperus cephalanthus, commonly known as the buttonbush flatsedge, is a species of sedge that is native to southern parts of North America and South America.
Cyperus cephalanthus was jointly named and described by the American botanist John Torrey and the English botanist William Jackson Hooker. In an influential monograph published in 1836, Torrey acknowledged the many contributions of Hooker, which included "a set of Mr. Drummond's plants collected in Louisiana and Texas".. The acknowledgment refers to the Scottish naturalist Thomas Drummond who collected the type specimen. , the botanical name Cyperus cephalanthus is widely accepted.