Ulothrix

a genus of green algae in the form of unbranched, attached filaments consisting of one row of mononuclear cells with one parietal bandlike chloroplast with pyrenoids. Zoospores, spores, or isogametes are formed in the cells of the filament during reproduction. The unicellular sporophyte is sometimes on a mucous stalk; it produces four to 16 haploid zoospores or spores. There are about 25 species, distributed in fresh waters and seas.