A division of the plant kingdom (also known as Chlorophyta or Chlorophycophyta) comprising all algae that have chlorophyll a and b except the Euglenophyceae, and that in all other respects are so different as to suggest a separate origin of their photosynthetic pigments. Three classes, Charophyceae (charophytes), Chlorophyceae (green algae), and Prasinophyceae, are recognized.