Phylum Phaeophyta
Phaeophytes, like most photosynthetic protists, have traditionally been classified as plants. However, phaeophytes are not closely related to land plants; their cells contain different pigments, such as chlorophyll c and fucoxanthin. They also lack the plasmodesmata and starch production of land plants and their relatives. The Phaeophyta are almost entirely marine, frequently dominating rocky shores in cold and temperate waters throughout the world. The giant kelps also belong to this phylum.
brown algae
The cell wall of the brown algae consists of a cellulose differing chemically from that of plants. The outside is covered with a series of gelatinous pectic compounds, generically called algin; this substance, for which the large brown algae, or kelps, of the Pacific coast are harvested commercially, is used industrially as a stabilizer in emulsions and for other purposes. They play an important role in marine environments, both as food and for the habitats they form. For instance Macrocystis, a kelp of the order Laminariales, may reach 60 m in length, and forms prominent underwater forests.Rockweed is a “brown” sea vegetable that grows in the intertidal zone on both sides of the North Atlantic. It is rich in a wide range of minerals, vitamins, and a host of bioactive compounds.