The first plants to colonise the foredunes are lyme grass, sea couch grass and marram grass. These plants are drought-resistant and capable of withstanding burial by the shifting sand. As they grow up through the sand, they help trap more sand and so the dunes increase in height. Here the dunes may typically reach up to 5 metres. Other pioneer plants include sea rocket, saltwort and ragwort. The marram grass which may reach 50-120cms. in height, has an extensive root system which helps to bind the sand together and young shoots grow up from the spreading roots or rhizomes. The picture on the right shows a single marram grass plant.