Smooth cordgrass is an important primary producer in salt marshes.
Smooth cordgrass is an important primary producer in salt marshes.
Courtesy: NOAA

Smooth Cordgrass (Spartina alterniflora)

Alternate common name: Saltwater Cordgrass, Marsh Grass.
Appearance: Tall, smooth grass. May be submerged at high tide. Grows 3 to 7 feet high. A shorter form, 6 to 12 inches high, occurs in low-oxygen areas of the high marsh. Green in spring and summer, turns light brown in late fall and winter. Flowering stalk visible in summer and fall.
Habitat: Intertidal zone of salt marshes, banks of bays and creeks.
Seasonal appearance: Blooms July to August.


Saltmarsh cordgrass is a tall, smooth grass ranging in height from 6 inches to 7 feet. Smooth cordgrass grows in three different sizes depending on its location in the salt marsh. It grows tallest near the water, is an intermediate size behind large cordgrass, and is shortest near the high marsh meadow grass. The shorter smooth cordgrass can often be found in areas of low elevation in the marsh. The flowering stalks resemble wheat and are arranged along one side of the stalk, similar to salt hay grass. Its leaves are thick and wide, and the root structure is strong and complex.

Life History and Growth

Smooth cordgrass is one of the most common forms of marsh vegetation found in Rhode Island salt marshes and is a vital plant species in the estuary. Often only a small amount of smooth cordgrass (fringe) is found extending from the high marsh to the water. However, smooth cordgrass also occurs in large fields, usually near the head of tidal creeks. This plant is important to marsh health due to the high volume of organic material it contributes during decomposition. In fact, smooth cordgrass is the most productive of the marsh grasses.

Located in low marsh areas, it is flooded twice daily by the tidal action of the estuary. The complex root system of the smooth cordgrass helps bind it to the banks, preventing the tide from eroding the shoreline. Although it relies primarily on groundwater absorbed through the roots, smooth cordgrass is able to extract fresh water from salt water when the need arises.

Special Notes

Adapted from The Uncommon Guide to Common Life on Narragansett Bay. Save The Bay, 1998.