Oocystis is a genus of algae from the class of Trebouxiophyceae.


Oocystis forms lemon-shaped to elliptical, unbegeißelte cells (length: 3-65 microns ) with a nucleus and one or more parietal chloroplast with pyrenoid. The cells live singly or in groups of two, four or eight cells in the swollen blistered mother cell wall. They are summarized in part to higher-level associations. The cell wall is smooth, occasionally it has polar thickenings.


Asexual reproduction occurs by the formation of two, four or eight ( rarely more) car spores.

Sexual reproduction is not known.

Types (selection)

  • Oocystis lacrusta
  • Oocystis marssonii
  • Oocystis parva
  • Oocystis Pussila
  • Oocystis ruprestis
  • Oocystis solitaria


The genus lived in the plankton and benthos of lakes, ponds and lakes, and in marshes and in the ground.


  • Karl -Heinz Linne von Berg, Kerstin Hoef -Emden, Birger Marin, Michael Melkonian: The Cosmos algae leader. The main freshwater algae under the microscope. Franckh Cosmos, 2006, ISBN 3-440-09719-6