The dunes are separated into uplands and wetlands habitats. Uplands include the fore dunes, back dunes, and sandy beaches. Dunes can occur in three different formations. Primary Foredunes are parallel to the shore and support sparse vegetation. Parabolic dunes are "U" shaped and perpendicular to the shore with vegetative ridges. Moving sand sheets consist of constantly moving sand, making it hard for vegetation to settle. The fore dunes begin at the high tide line, where only low growing plants with deep root systems (such as sand verbena) can live. The strong winds, salt spray, and massive amounts of sand make this area uninhabitable for other types of plants. Plants in the dunes adapt growth forms to survive high winds. Some grow close to the ground to avoid the wind and others adopt a Krummholz growth form. The back dunes, just behind the fore dunes, are stabilized and covered with plants. The back dunes are dominated by shrub species like mock heather, dune lupine, coastal buckwheat, and blochman's senecio. The sandy beaches are a harsh environment with no plants able to survive there. The wetlands include the areas that contain water: salt marshes, fresh and brackish-water marshes, swamps, and mudflats. Plants that live there are adapted to dynamic environmental conditions including high salinity concentration and extreme temperatures. Solutions that the plants can take to adapt to high salinity are large tap roots to reach the perched water table, thick cuticle to prevent water loss, and succulence.