Invasive Plants of California's Wildland

Common cordgrass (Spartina anglica) is a perennial, spreading grass from one foot tall in spring to six or even eight feet tall in fall. It grows naturally only in intertidal estuarine habitats; often in large, nearly monospecific stands in coastal or bayside marshes. It forms dense clumps, compared to the more open clumps of smooth cordgrass (S. alterniflora). Common cordgrass stems are hollow in cross section, round, and about half the diameter of smooth cordgrass. Leaves are hairless, and leaf tips are sharply pointed. Young, healthy green shoots and leaf sheaths are often streaked with red or purple just below the sediment surface. Common cordgrass also has rows of hairs where the leaf meets the stem (ligules) that are up to a third of an inch long, compared to the less than one-fifth-inch length of smooth cordgrass ligules.

Common cordgrass is found in coastal salt marshes, mud flats, and estuarine habitats similar to that of Spartina alterniflora in California coastal counties. In California it is currently found only in South San Francisco Bay.

Common cordgrass is a fertile hybrid between Spartina maritima (a British species) and smooth cordgrass (S. alterniflora). This hybrid was introduced into Washington in 1967 at Skagit Salt Marsh and dispersed down Puget Sound. It may have dispersed to California with south-flowing ocean currents, but this has not been established.

Common cordgrass seeds are spread by wind and water currents, but can also spread vegetatively by rhizomes and fragments that break off and move downstream.

This cordgrass, like other non-native species of Spartina, traps sediment, builds marshes from the edge out, and overgrows native vegetation. It alters the course of succession and produces a monospecific stand that has much less value for wildlife than the native marsh flora. It is believed that common cordgrass caused the dieback of the native S. maritima in the United Kingdom (Doody 1984).

Research has not been conducted on removal of common cordgrass, but recommendations for removal of smooth cordgrass Spartina alterniflora should be effective.