YELLOW-GREEN ALGAE

members of the division Xanthophyta (about 6,000 species), once classified with the green algae on the basis of similarity of body organization. The Xanthophyta are distinguished by their food reserve (oil), the quantity of B-carotene in their plastids, and motile bodies with unequal flagella. Frequently their cell walls are two overlapping halves. The usual method of asexual reproduction is by motile zoospores and nonmotile resting aplanospores. Sexual reproduction is rare; the genus Vaucheria (q.v.) is an important exception.