Dunes act as flexible barriers to ocean storm surges and waves. As the small mound gets bigger, plants like sea rocket, seaside goldenrod, prickly pear cactus, mullein, wild rose and poison ivy or beach grass can colonize it. The roots of the plant hold the sand in place, accumulating even more sand and as a result, establishing a dune. It spreads quickly by its specialized roots, called rhizomes that can grow down and sideways through the sand. These rhizomes, along with the roots of the plant, form a network that helps hold the entire dune in desert beach seashore. 4K UHD 3840×2160 30p.