The beach dune habitat is characterized by several rows of sand dunes. “Frontal” or “primary” dunes are vegetated with grasses including sea oats, bunch grass, and beach grass. Among other plants growing in primary dunes are Florida rosemary, railroad vine and beach morning glories. “Secondary” dunes, further inland, support saw palmetto, slash and sand pines, and scrubby shrubs and oaks. Growing among the dunes are such species as cordgrass, salt-grass, pine trees, purslane and pennywort. The scrub and grasses growing on the dunes are vital to the health of the beach habitat. Without the critical holding power of dunes and their plants, the beaches would blow and erode away.