Ammophila (synonymous with Psamma P. Beauv.) is a genus of flowering plants consisting of two or three very similar species of grasses. The common names for these grasses include marram grass, bent grass, and beachgrass. These grasses are found almost exclusively on the first line of coastal sand dunes. Their extensive systems of creeping underground stems or rhizomes allow them to thrive under conditions of shifting sands and high winds, and to help stabilize and prevent coastal erosion. Ammophila species are native to the coasts of the North Atlantic Ocean where they are usually the dominant species on sand dunes. Their native range includes few inland regions, with the Great Lakes of North America being the main exception.