There are no flagellated cells formed in either sexual or asexual reproduction. Cell division does involve centrioles, and hence the presence of potential flagellar bases indicates an algal affinity. The absence of flagellated cells in this class is similar to that in the class Rhodophyceae. The cell wall is composed of cellulose. The cells are uninucleate, and the chloroplast type is varied.
Sexual reproduction is by conjugation.
The style of conjugation and the ornamentation of the zygospores are species specific characteristics. Although only 50 genera are represented in this class, there are over 6000 species. As mentioned earlier, the zygospore wall is capable of fossilization, and from fossil records, extant genera, Spirogyra and Mougeotia were present in the Carboniferous era. In the field Spirogyra forms extensive submerged mats. As indicated earlier, during sexual reproduction, the coloration of the mats changes from a brilliant grass green to a yellow-green and yellow color.