Polygonum basiramia (synonym Polygonella basiramia) is a rare species of flowering plant in the knotweed family known by the common names wireweed, hairy wireweed, purple wireweed, and Florida jointweed. It is endemic to Florida in the United States, where it is limited to the central ridges of the peninsula, including the Lake Wales Ridge. It is threatened by the loss and degradation of its habitat. It is a federally listed endangered species of the United States.