| Noun | 1. | order Chlorococcales - unicellular green algae that reproduce by spores protoctist order - the order of protoctists Chlorophyceae, class Chlorophyceae - algae distinguished chiefly by having flagella and a clear green color, their chlorophyll being masked little if at all by other pigments Chlorococcum, genus Chlorococcum - type genus of Chlorococcales; unicellular green algae occurring singly or in a layer on soil or damp rock genus Chlorella - nonmotile unicellular green algae potentially important as source of high-grade protein and B-complex vitamins |