algal bloom




Examples of Tolypothrix

tolypothrix (image 2)

400X total magnification; 10 μm scale bar.

tolypothrix (image 1)

400X total magnification; 10 μm scale bar.

tolypothrix (image 3)

400X total magnification; 10 μm scale bar.


Heteropolar filaments with basal heterocytes and free apical ends, with false branches arising just below the heterocytes; false branching is usually single, less frequently with double false branching; filaments usually flexuous. Uniseriate trichomes; slightly wider or narrower towards the ends in some species; unconstricted to slightly constricted at crosswalls. Sheaths thin or widened; sometimes lamellated; only one trichome in each sheath. Cells typically cylindrical; sometimes barrel-shaped (usually near trichome ends); usually blue-green to olive-green; cell content sometimes with a few granules; terminal cells usually rounded, and sometimes somewhat enlarged. Filaments attached to substrate, or floating if benthic colonies separate from the substrate and float to the surface; colonies sometimes in the form of bush-like or shrub-like clusters; in fascicles or tufts, or forming woolly mats.

Heterocytes mostly basal, at the bases of false branches; later intercalary as well; solitary or sometimes in short rows; spherical, barrel-shaped, cylindrical, or disc-shaped (flattened, squished). Without akinetes.


Aquatic or subaerial, but more commonly aquatic. Aquatic in unpolluted freshwater springs, streams, and alkaline swamps; attached to rocks or aquatic plants, submerged among periphyton, or mat-forming. Subaerial on wet stones, soils, or bark.


  • Johansen, J. R., & Komárek, J. (2015). Filamentous Cyanobacteria. In J. D. Wehr, R. G. Sheath, & J. P. Kociolek (Eds.), Freshwater Algae of North America: Ecology and Classification (2nd ed., pp. 183-196). Waltham, MA: Elsevier.
  • Komárek, J. (2013). Cyanoprokaryota-3. Teil/Part 3: Heterocytous Genera (J. R. Johansen, Ed.). In B. Büdel, G. Gärtner, L. Krienitz, & M. Schagerl (Eds.), Süßwasserflora von Mitteleuropa (Vol. 19/3, pp. 427-429). Heidelberg, Germany: Springer Spektrum.