cordgrass, (genus Spartina), genus of 16 species of perennial grasses in the family Poaceae. Cordgrasses are found on marshes and tidal mud flats of North America, Europe, and Africa and often form dense colonies. Some species are planted as soil binders to prevent erosion, and a few are considered invasive species in areas outside their native range. Prairie cordgrass (Spartina pectinata) and gulf cordgrass (S. spartinae) are the most widely distributed North American species.
Cordgrasses are erect, tough, long-leaved plants that range from 0.3 to 3 metres (1 to 10 feet) in height. Most species grow in clumps, with short flower spikes alternating along and often adherent to the upper portion of the stems. Many spread vegetatively with rhizomes (underground stems) that send up new plants.