it is a stout perennial grass with horizontal and vertical rhizomes, very bushy, up to 120 centimeters tall. Horizontal rhizomes anchor the young plants and produce new shoots around the parent plant. Vertical rhizomes develop, branching from a horizontal rhizome, as sand accumulates around plants. Leaves are linear and narrow, with prickly tip, and can reach up to 90 centimeters. Where the leave attachs to the stem, there is a characteristic ligula divided into two thin segments of 10 - 30 millimeters each. The inflorescence is a spike panicle 7-30 centimeters long, composed by spikelets 9-14 millimeters long, each one carrying a flower. It flowers from May to August, mature fruits are dispersed in September and seeds germinate the following spring. Seedling survival is low as a result of desiccation, burial, and erosion. Reproduction is primarily vegetative by rhizomes, whose fragments are dispersed along the shore by wind and water.

it plays an important role in the process of dune formation. Young plants become established along the upper beach, often in the lee of driftwood or other beach plant species. As the grass grows taller, wind is deflected upward over the plant. An equilibrium is established between the growth of A. arenaria and sand deposition. The plant causes the wind to slow and sand particles to be deposited. Sand deposition stimulates growth of A. arenaria, which in turn encourages more sand deposition. Once dune is formed and stabilized by european beachgrass, other species settle. It can withstand burial by as much as one meter per year. Sand burial promotes both leaf elongation and development of vertical rhizomes from axillary buds on the horizontal stems. Internode length of vertical rhizomes varies according to the amount of sand burial and indicates seasonal sand accretion.