beach grass or marram grass (mârˈəm) [key], any species of the genus Ammophila, perennial grasses used to control the shifting of sand dunes, thereby protecting sandy coastal areas. The European beach grass ( A. arenaria ) has been used to hold dunes in Europe and was early planted at Cape Cod to bind the sands; later it was used at Golden Gate Park and elsewhere in the United States. The American beach grass ( A. breviligulata ) is native to dunes of the Great Lakes and much of the eastern seacoast. Beach grasses have creeping rootstocks that rapidly form an extensive root system. Beach grasses are classified in the division Magnoliophyta, class Liliopsida, order Cyperales, family Gramineae.