ABSTRACT It is commonly believed that only a single species of Phragmites (Gramineae) occurs in North America. Here, field observation shows greater morphological differences than previously recognized between an introduced East Coast population and a native Gulf Coast population, and are sufficient to justify specific rank for each. These differences are discussed and illustrated, and a key is provided for separation. The introduced population, and the widespread northern native population (not studied), are treated as P. australis, and the Gulf Coast population as P. karka. Nomenclatural uncertainties are noted.