marram

Marram, or marram grass, is Ammophila arenaria, a perennial grass native to the sandy shores of Europe and North Africa. It has been introduced widely beyond its native range for dune stabilization and erosion control, notably on coastlines in North America, Australia, and parts of Asia. In some regions it is considered invasive due to its aggressive growth and tendency to form dense monocultures that displace native dune vegetation.

It forms tussocks or clumps with erect stems reaching up to about a meter in height. Leaves are long, narrow, and stiff, with sharp edges, adapted to dry, sandy conditions. A powerful rhizome system extends underground, binding sand and promoting dune formation.

Marram tolerates salt spray, wind, and arid conditions, and it propagates by seed and by aggressive rhizome spread. It stabilizes dunes effectively, reducing erosion and providing habitat for some coastal species. However, excessive stabilization can reduce dune mobility and reshape natural dune gradients, potentially impacting other organisms. In non-native regions, it may outcompete native grasses such as Ammophila breviligulata in North America and disrupt dune ecology. Management options include monitoring, restoration with native species, and, in some cases, mechanical removal or selective planting of natives.