Landward of the beach along most of Padre Island is a ridge of vegetated coastal sand dunes, composed of sand blown from the beach by onshore winds. These dunes are fairly well stabilized by vegetation, except where wind, water, or human activity have destroyed the vegetation exposing dunes and transforming them into actively migrating forms. The vegetation is a dense cover composed primarily of grasses: bitter panicum, sea oats, gulf dune paspalum, and dropseed. Some of the forbs present are beach morning glory, beach evening primrose, railroad vine, prairie senna, and gulf croton.