European beachgrass, also known as Marram and Marram grass (Ammophila arenaria) is a coarse perennial coastal grass in the Poaceae family.

Native to coastal areas in Northern Africa; the Arabian Peninsula, Cyprus, Israel, Lebanon and Turkey; and Northern, Middle, East, Southeastern and Southwestern Europe, it plays an important role in dune formation and erosion prevention.

As an invasive, introduced species in North America, it is threatening coastal sand dunes in the eastern and western United States, where it is displacing native dune species (such as the American beachgrass Ammophila breviligulata) and significantly altering the structure of the dune systems it invades. Control of this invasive species can only be achieved at this time through ongoing manual removal. It can also extend inland for several miles. It has also been naturalized in Australia and Hawaii.