Beach grass, American, European, and hybrid

Ammophila breviligulata, A. arenaria, A. breviligulata x A. arenaria

Beach grass, American, European, and hybrid

Family: Poaceae

Other Scientific Names:

Calamagrostis breviligulata, Calamagrostis arenaria, Ammophila arenaria var. breviligulata, Ammophila arenaria subsp. breviligulata, Ammophila breviligulata, Ammophila arenaria, Ammophila breviligulata x Ammophila arenaria


Other Common Names: American beachgrass, European beachgrass, hybrid beachgrass, North American marram grass, European marram grass
Weed class: C
Year Listed: 2024
Native to: European beach grass (Ammophila arenaria) is native to the banks of the coasts, lakes, and rivers of Europe, the Mediterranean, and Eurasia. American beach grass (Arenaria breviligulata) is native to the East Coast North America along the Atlantic from North Carolina to Newfoundland, and inland through the Great Lakes.
Is this Weed Toxic?:

Non known to be.


Why Is It a Noxious Weed?

Non-native beach grasses push out all native coastal sand dune plant species. They create larger and more permanent sand dunes than native dune plants would, which permanently change the hydrology and ecology of the habitat behind the dunes. Beach grasses are very prone to wildfires. 

Non-native beach grasses were planted to hold sand and protect infrastructure along the West Coast of North America. Due to this important role, these beach grasses are Class C, meaning they are not required for control, so agencies, municipalities, and individuals can choose to leave beach grasses on their properties, to protect from wave action, storms, blowing sand, and shifting dunes.

How would I identify it?

General Description

Flowering stems can grow over a meter tall, while the grass blades are shorter. They grow in large tussocks and bunches, which can spread over an entire dune or beach.

Flower Description

Beach grasses do not frequently make inflorescences. When they do, the panicle can be up to 7 inches long, made up of many small spikelets, each with one floret. 

Leaf description

Long, thin, grey-green grass blades, which can be almost 3 feet long. In the winter, they turn brown and die back into flattened mats, which are usually buried by sand.

Stem description

The round, thin, flowering stem can be up to a meter long, and drooping with the weight of the inflorescence spike.

Fruit Seed Description

Brown, oval-shaped, and fall off the grass while still enclosed by a hard shell. Plants make very few seeds compared to the number of florets

May Be Confused With

The only native dune grass to Washington is the American dune grass, Leymus mollis. You can use the following resources to differentiate between our native dune grass and the invasive beach grasses:

iNaturalist beach grass project

ID guide pamphlet

Where does it grow?

Sand dunes on the coasts of salt and fresh water. Mostly known along the Pacific coast of Washington, though there are sand dunes they can grow on in Puget Sound and other locations around Washington and the Columbia River.

How Does it Reproduce?

Beach grasses reproduce primarily by underground rhizomatous spread, as well as cloning when bunches break off with wave action and float to a new site. 

Beach grasses can reproduce by seed, which is spread on the wind.

How Do I Control It?

Manual:

Hand pulling and digging can be effective, but time consuming. 

Heavy machinery, like bulldozers can be used, especially in conjunction with manual and chemical controls.

Cultural:

Controlled burns, in tandem with manual or chemical methods can be effective.

The army corps of engineers have had success with spraying salt water on beachgrass until salinity rises above 2%.

Chemical:

Glyphosate with a non-ionic surfactant is effective with follow up treatments. Imazapyr is preferred over glyphosate.

For chemical rates, and more control information can be found in the Western Weed Management Website.

For More Information

Our written findings on European, American, and hybrid beach grasses

Additional Photos