The Chlorellales are an order of green algae in the class Trebouxiophyceae.

[1] The Chlorellales include mostly freshwater or terrestrial (rarely marine), coccoid algae.

[2] Molecular phylogenetic studies mostly tend to find Chlorellales to consist of two sister clades, corresponding to Chlorellaceae and Oocystaceae; however, in some studies the two are not sister to each other, making Chlorellales not monophyletic.

[3] Genera of uncertain placement include:[4]

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