Plant
Algae comprise several different groups of organisms which produce food by photosynthesis and thus have traditionally been included in the plant kingdom. The seaweeds range from large multicellular algae to single-celled organisms and are classified into three groups, the brown, red and green algae. There is good evidence that the brown algae evolved independently from the others, from non-photosynthetic ancestors that formed endosymbiotic relationships with red algae rather than from cyanobacteria, and they are no longer classified as plants as defined here.
Zostera muelleri
Seagrasses are a flowering plant species, not to be confused with seaweed, which do not form flowers, fruits, and seeds to reproduce. Seagrasses are important to the marine ecosystem for many reasons. For one, they provide food, homes, and breeding grounds to a variety of marine species. Secondly, meadows of seagrass are important carbon reservoirs or sinks, sequestering 10-18% of the ocean's carbon accumulation for long-term storage. Seagrasses also enhance sediment accretion, and protect coastlines from destructive wave energy.