The coral reef ecosystem extends far beyond the stony skeletal structures set up by the coral polyps. It includes waving meadows of seagrasses, spidery networks of mangrove roots, and even the clear blue ocean currents that wash along the reef's edge. All of these components are crucial for the colorful array of life we see at the reef. Much of that life begins in the seagrass beds. These marine flowering plants differ from algae in that they have true roots, stems, and leaves.
Seagrasses produce seeds, although their flowers are often inconspicuous.
In addition, Seagrasses form horizontal stems called rhizomes. Scientists believe these aquatic plants are derived from terrestrial plants which returned to the sea by gradual, progressive steps of acclimation to shallow fresh water, to shallow brackish water, and finally to submersion in marine water. The adaptation to a submerged life in marine waters involves a complex set of anatomical, morphological and physiological changes. Special adaptation to life underwater include large air canals in the grass blades. The rhizomes, too contain continuous air canals, as well as storing necessary starch for the plants.