Historically recognized algae taxa

The prasinophytes are a group of unicellular green algae. Prasinophytes mainly include marine planktonic species, as well as some freshwater representatives. The prasinophytes are morphologically diverse, including flagellates with one to eight flagella and non-motile (coccoid) unicells, as well as dormant or cyst stage phycoma. The cells of many species are covered with organic body scales; others are naked. Well studied genera include Ostreococcus, considered to be the smallest (ca. 0.95 μm) free-living eukaryote, and Micromonas, both of which are found in marine waters worldwide. Prasinophy

thumb|right|Various algae, formerly classified within Chlorococcales Chlorococcales is a formerly recognized order of green algae in the class Chlorophyceae. , the type family Chlorococcaceae was placed in the order Chlamydomonadales.

thumb|right|Bryopsis plumosa Bryopsidophyceae is an unaccepted class of chlorophyte green algae. The order Bryopsidales has been included in the class Ulvophyceae. However, several recent phylogenomic studies have recovered Bryopsidales as sister clade to the Chlorophyceae.

thumb|right|Scientific illustration|Illustration of [[Tetraspora gelatinosa]] The Tetrasporales are a formerly recognized order of green algae, specifically the Chlorophyceae, now included in Chlamydomonadales. AlgaeBase places Tetraspora and Tetrasporaceae in Chlamydomonadales.