[2] Algae such as Chlorella are important model organisms for plant physiology and biochemistry, because of they are easy to cultivate and grow rapidly.

In addition to autotrophic members that contain a chloroplast, the family includes genera which have lost the ability to photosynthesize are therefore heterotrophic.

These genera, namely Prototheca and Helicosporidium, are colorless, single-celled organisms that resemble yeast, and are opportunistic pathogens of animals.

[2] Current hypotheses on the phylogenetic relationships between taxa are as follows:[2][8] Chlorella Micractinium Actinastrum Carolibrandtia Hindakia Lewiniosphaera Heynigia Didymogenes Brachionococcus (syn.

Aliichlorella)[9] Meyerella Hegewaldia Parachlorella Marasphaerium Dictyosphaerium (polyphyletic) Compactochlorella Mucidosphaerium Planktochlorella Closteriopsis Coronacoccus Masaia Marinichlorella Dicloster Kalenjinia Muriella terrestris Picochlorum Laetitia Nannochloris Edaphochloris Pumiliosphaera Koliella pro parte Catena Gloeotila contorta Nomia Ava Chloroparva Pseudochloris Endolithella mcmurdoensis AHP clade (Auxenochlorella, Helicosporidium, Prototheca) Oocystaceae (outgroup) Not all genera are included, as some (e.g. Cylindrocelis, Palmellochaete, etc.)