Closterium sp. Nitzsch, 1817
The unicells are elongate, markedly attenuated at the poles and without a median constriction. Most species have cells that are distinctly lunate or arcuate. The cell walls are longitudinally striate with delicate pores, the latter only seen with special methods of preparation. Because of impregnation with iron compounds, the cells may appear brownish or yellowish brown. The two chloroplasts, one in each semicell, may be entire or with longitudinal ridges. The pyrenoids are usually few and arranged in an axial axis, although sometimes they are plentiful and irregularly scattered. There is a prominent vacuole at each pole of the cell. The nucleus is at the centre of the cell.
This is one of the commoner desmids usually seen in hard water. Species are differentited by cell shape, degree of curvature, wall ornamentation and chloroplast structure.
Asexual reproduction is by cell multiplication via transverse division. Mature cells may undergo conjugation whereby the cell walls break and the cell contents migrate towards each other. The resulting zygote germinates forming two individual cells.
Bold, H. C., C. J. Alexopoulos & T. Delevoryas, 1987. Morphology of plants and fungi. Harper & Row, New York. (5th ed.). 912pp.