Phaeophyceae Brown Algae

Brown Algae

1. Phaeophyceae Brown Algae

2. It contain’s 240 Genera & 1500 Species. Golden Brown Xanthophyll Fucoxanthin (C 40 H 54 O 6 ) Pigments. It also contains chlorophyll A & C. 99.7% marine & few are fresh water, Pleurocladia & Lithoderma(Freshwater).

3. Plant body is multicellular and highly differentiated both externally and internally. Unicellular,colonial & unbranched filamentous forms are Completely absent. Size ranges from few c m( Ectocarpus ) to 100m ( Macrocystis pyrifera ) largest form known as kelps or Rockweed.

4. Root-like structure called a  holdfast . Small Stalk , stem like structure called Stipe . flattened structure called the lamina, blade or frond which performs photosynthesis. Some contain special gas-filled bladders called  pneumatocysts .

5. The cell wall is differentiated into outer and inner layers. The outer mucilaginous layer has fucinic and alginic acid , but the inner layer is mainly cellulosic . The reserve foods are commonly laminarin and mannitol . Sucrose and glycerol are also present in some members.

6. Reproduce by all three means: vegetative,sexual & asexual. Fragmentation ( S phacelariales ) Asexually by motile zoospores(pear shaped 2 unequal flagella.) Sexually by motile gametes ( biflagellated with 2 laterally attached flagella) Sexual reproduction may be oogamous , isogamous or anisogamous .

7. L aminaria Ectocarpus

8. Fucus S argassum

9. Economic Importance Widely used as edible sea weeds: Laminaria , Sargassum . Alginic Acid used as thickening agent in food industry. Alginic Acid is also used in batteries, pills , surgical threads. Kelps are used for making soap & glass. Laminaria used for treating iodine deficiency.