Staurastrum is a large genus of desmids (Desmidiaceae),[1] a group of green algae closely related to the land plants (Embryophyta).

[5] Biradiate individuals have long, arm-shaped extensions (termed "processes") attached to the main body of the semicells.

The smaller species may also be confused with Tetraedron or various xanthophyte algae, but differ in shape, ornamentation, and chloroplast morphology.

[7] Several attempts have been made to dismantle the genus and split it up into smaller, more homogeneous units, such as G. M. Palamar-Mordvintseva's segregate genera Cylindriastrum, Cosmoastrum, and Raphidiastrum.

[6] Staurastrum, as well as other desmid genera, live primarily in acidic lakes, ponds, and swamps with low nutrient levels.