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Division Phaeophyta -Brown algae (Seaweeds), The main characteristics of Phaeophyta are:, , 1, , 1-Cell construction: cellulose fibers bound with Alginic, acid Fucuni acid, Fucoidan form cell walls., 2- Food reserves: laminarin, mannitol., 3- reproduction of this algae takes place by both sexual, and asexual means. Higher phaeophyta have life cycle, , consisting of both haploid, diploid stages and alternation, of generation. The thallus representing haploid stage and, diploid stage may be similar (isomorphic) or different, , (hreteromorphic)., 4-Photosynthetic pigments: chlorophyll a and , beta, carotene, Dinoxanthin ,violaxanthin, and Fucoxanthin., These pigments give brown algae color and Fucoxanthin, pigment are dominant, , 5-phaeophyta(Sea weeds) belonging to order Laminarales are, called kelps can reach to about 70 meters in length. Kelps are, the only algae with a significant internal tissue differentiation., Kelp grovws in "underwater forests" in shallow oceans, Though, , true conductive tissues, xylem and phloem are absent., 6-Brown Algal Tissue Differentiation: Epidermis, Cortex and, Medulla, , 6-They can adapt to a wide marine environment; tidal,, intertidal and deep zones., 8-Some members of phaeophyta have, ers, , Containin, , or airbags, meant for floating photosynthetic pa, near the water surface for harvesting light.

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6-They can adapt to a wide marine environment; tidal,, , intertidal and deep zones., 8-Some members of phaeophyta have Containing blar', or airbags, meantfor floating photosynthetic parts on c 2, near the water surface for harvesting, light., , CoLL, , LIGHT, , LA, , 9-They often cause nuisance to aquarium environment by, developing brown patches on any exposed surfaces such as, rocks or gravel., , 10- Morphology, Members of this division, , typically have three parts. They, , are, , A] Holdfast which attachment the alga to the substrate, B] Stipe which is stem-like, CI Laminae (blades) which are leaf-like, Blade, Gas Bladder, Frond, , Stipe, Holdfast, , Brown algae, , Division of brown algae are classified into three classes, depending on the type of life cycles of the species, , 1-Class: s0generate, , 2-Class:Hetrogenerate, 3-Clas:Cyclosporea