Pediastrum

Pediastrum is a genus of green algae, in the family Hydrodictyaceae. It is a photoautotrophic, nonmotile coenobial green alga that inhabits freshwater environments. The name Pediastrum comes from the Greek root words pedion, meaning "plane", and astron, meaning "star", referring to its overall shape.

== Morphology == Pediastrum develops colonies with a fixed number of cells, termed coenobia. In this case, the coenobia are composed of between 22 and 27 cells, which are orderly arranged in a flat disk. The diameter of a single coenobium ranges from 20 to 80 μm, making them microalgae. Cells in Pediastrum are dimorphic, consisting of interior cells and peripheral cells, distinguished by their position in the colony and by their shape. Some species have inter-cellular spaces between their interior cells. The peripheral cells surround the interior cells, and they usually possess bristles, V-like cutting edges, or wavy projections.