Parapediastrum is a genus of green algae in the family Hydrodictyaceae.

[2] It is fairly common in freshwater regions throughout the world.

[3] Parapediastrum forms flat, disc-shaped colonies, termed coenobia, of cells in powers of two, usually four, eight, 16, or 32.

This distinguishes it from Pediastrum and other genera, which have marginal cells with one or two lobes that are never subdivided further.

[4] In 2005, molecular phylogenetic analyses showed that Pediastrum sensu lato was paraphyletic with respect to Hydrodictyon.