Common Cordgrass

Report it

If you think you have found an aquatic invasive species:

1. do not return the species to the water
2. take photos
3. note:
   • the exact location (GPS coordinates)
   • the observation date
   • identifying features
4. contact us to report it

Identifying features

Common Cordgrass is a hybrid, perennial, salt-tolerant grass with a distinct 45 to 90 degree angle between the leaf blade and the stem. Round, hollow stems grow in roundish clumps up to two metres in height. The leaf blades, 36 to 46 centimetres in length and up to 12 millimetres wide, are flat, rough and green-gray in colour. Cordgrass sprouts in the spring and blooms from July through November. The seeds resemble wheat and are found on one side of the stem.

Where it has been found

It was discovered in the summer of 2003 in Boundary Bay and Roberts Bank, near the Fraser River estuary. It has recently been discovered in Baynes Sound and Courtenay on Vancouver Island.

Habitat

Common cordgrass can grow rapidly in intertidal zones, such as mudflats and beaches.

Ecological and economic impacts

Three species of Spartina, commonly known as cordgrasses, have invaded coastal estuaries of B.C. As these species proliferate, they trap sediment with their large root masses, raise the elevation of intertidal areas, fill drainage channels, and replace natural mud and sand flats, native eelgrass and algae beds. It is extremely aggressive and will displace existing habitat as it spreads over mudflats via seeds and/or rhisomes and move upwards into natural salt marshes.

The results can be serious:

• A loss of critical rearing habitat for fish such as juvenile salmon, clams, oysters and crab.
• A loss of valuable habitat for migrating shorebirds and waterfowl. Boundary Bay is a major resting and feeding area for more than 320 bird species
• An increase in the risk of flooding
• A loss of water access from shoreline areas and beaches and for boats
• A loss of more diverse, native plant species
• Disruption of saltwater ecosystem structure and function
• Competition with native marsh species
• May negatively impact native wildlife
• Competition with other plant species

Mode of dissemination

The plants can spread in B.C. by birds, animals, humans, and water currents. This species was introduced to some locations intentionally to stabilize banks/shorelines and seeds have been transported unintentionally with oyster transplants.