Sexual reproduction
Sexual reproduction shows considerable variation in the type and formation of sex cells and it may be isogamous e.g. "Chlamydomonas, Ulothrix, Spirogyra", anisogamous e.g. "Chlamydomonas, Eudorina" or Oogamous e.g. "Chlamydomonas, Volvox". "Chlamydomonas" has all three types of sexual reproduction.