Chlorophyta

Chlorophyta, or green algae, are composed of species that occur in terrestrial, freshwater, and marine environments and display a variety of morphologies—from single-celled organisms to complex, multicellular forms. Bryophytes (mosses and others) and vascular plants arose from chlorophytan ancestors.

Species in this phylum are characterized by having flagellated cells (with whiplike "tails") in which the flagella are similar in appearance. The flagella may be naked or covered with delicate hairs or scales, but they lack the tubular hairs of brown algal flagellated cells. The flagella are inserted apically. In some species, the flagellated cells are the only morphology exhibited by the species, but in green seaweeds flagellated cells occur only as reproductive cells.

The chloroplast is encircled by a double membrane and contains stacked thylakoids and often one or more pyrenoids surrounded by granules of starch, the storage polysaccharide. Chloroplasts are green because the predominant photosynthetic pigments, chlorophylls a and b, are not masked by other pigments, although accessory xanthophylls may be present.