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Planktothrix

Planktothrix is a genus of filamentous cyanobacteria (often called blue-green algae). P. agardhii is regarded as a type species of the genus. Like all the Oscillatoriales, Planktothrix species have no heterocyst and no akinetes, but are unique because they are planktonic, solitary trichome and have gas vacuoles. Before the work of Suda et al., some species of the taxon were grouped within the genus Oscillatoria. A tremendous body of work on Planktothrix ecology and physiology has been done by Anthony E. Walsby, and the 55.6 kb microcystin synthetase gene have been sequenced.

P. agardhii and P. rubescens are commonly observed in lakes of the Northern Hemisphere where they are known producers of potent hepatotoxins called microcystins.