Ulothrix sp. Kutzing, 1833
This is an unbranched filamentous alga of indefinate length. When young, the filament is sessile and attached to the substratum by a holdfast. The cells are uninucleate and capable of division to form zoospores and gametes. The chloroplast is a single girdle-shaped structure that partly or completely encircles the protoplast. According to species, the chloroplast extends the entire length of the cell or only part of the length. The number of pyrenoids may be from one to several.
Ulothrix is generally found in still or running water.
Vegetative propagation is by the accidental filament fragmentation. All cells except the basal holdfast are capable of division to form zoospores. These swarm and germinate into individual filaments. The cells are similarly capable of dividing to form biflagellate gametes. These gametes fuse with those from other filaments to form zygotes that germinate after a period of rest to give aplanospores or zoospores.
Bold, H. C., C. J. Alexopoulos & T. Delevoryas, 1987. Morphology of plants and fungi. Harper & Row, New York. (5th ed.). 912pp.