What class are the seaweed in?

Seaweeds are classified into three major groups; the green algae, the brown algae, and the red algae. Placement of seaweed into one of these groups is based on the pigments and colouration existing in the plant. Other seaweed features that are used to classify algae include: cell wall composition, reproductive characteristics, and the chemical nature of the photosynthetic products. Plant structure, form and shape are additional characteristics used to classify seaweed.