Chlorophyceae

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The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. For example the chlorophycean CW clade, and chlorophycean DO clade, are defined by the arrangement of their flagella. Members of the CW clade have flagella that are displaced in a "clockwise" (CW, 1–7 o'clock) direction eg. Chlamydomonadales . Members of the DO clade have flagella that are "directly opposed" (DO, 12–6 o'clock) eg. Sphaeropleales.

The following orders are typically recognised:

• Dunaliellales
• Chlamydomonadales (e.g. Chlamydomonas)
• Volvocales (e.g. Volvox)
• Chlorococcales (e.g. Chlorella)
• Oedogoniales (e.g. Oedogonium )
• Sphaeropleales
• Chaetophorales
• Microsporales
• Tetrasporales (e.g. Tetraspora )

In older classifications, the term Chlorophyceae is sometimes used to apply to all the green algae except the Charales, and the internal division is considerably different.