Beach grass, American, European, and hybrid

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

WA C Poaceae

Data Maturity Baseline

Washington State Classification

Class C — Widespread, County-Selected Control

Non-native beach grasses push out all native coastal sand dune plant species.

Quick Reference

Type

perennial herb

Origin

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.

Identification

Growth Habit

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.

Leaves

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.

Flowers

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.

Fruit & Seeds

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

Impact

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.

Ecology & Spread

Habitat

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. Click here to see a county-level distribution of beach grasses in Washington.

Spread Mechanisms

seed wind

Reproduction

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.

Regional Notes — Puget Sound