The Subclass Phytomastigina is a group of unicellular organisms that have flagella and obtain their nutrition through photosynthesis. This subclass is also known by other names such as the Phytomastigophorea and the Chloromonadida. The term Phytomastigina is derived from the Greek words 'phyto' meaning plant and 'mastigos' meaning whip, referring to the flagella on these organisms. Other common synonyms for this subclass include Chlorophyceae, Chlorophyta, green algae, and chloromonads. The diversity of organisms belonging to this subclass includes both freshwater and marine species, ranging from simple unicellular forms to complex multicellular colonies with distinct structures and growth patterns.