Carex arizonica M. Licher, G. Rink, and A. A. Reznicek (Cyperaceae) is a new species of riparian sedge in Arizona, USA and apparently Chihuahua, Mexico. Previously, these plants were determined variously as Carex meadii, C. aurea, or C. hassei. Carex meadii, reported from Arizona based on this entity, is now not known within Arizona. With mostly three stigmas, Carex arizonica would seem to be most closely related to C. klamathensis, a serpentine endemic in southwestern Oregon and northwestern California, which belongs to section Paniceae. However, the widespread Carex aurea of section Bicolores, which usually has flowers with two stigmas, may have played a role in the origins of C. arizonica.