Many scientists believe land plants evolved from green algae, especially the charaophytes (from Charaphyceae). Not only are the chloroplasts in the green algae the same as those of land plants, but the two share a number of biochemical and metabolic traits. In addition, both contain the same photosynthetic pigments: carotenes, xanthophylls, and chlorophylls a and b; cellulose is a major component of the cell walls of plants and algae, and both store their excess food (carbohydrates) as starch.