The Charophyta are a division of green algae,1] including the closest relatives of the embryophyte plants. In some groups, such as conjugating green algae, flagellate cells do not occur. The latter group does engage in sexual reproduction, and motility does not involve flagella, since they are totally lacking. Flagellate cells in the form of sperm are found in stoneworts (Charales) and Coleochaetales.
Because they exclude the embryophytes, the Charophyta make a paraphyletic group (although the division Charophyta is occasionally restricted to simply the Charales or stoneworts, which are monophyletic).[ci
tation needed] The Charophyta
plus the embryophytes make up the Streptophyta, which is a monophyletic group.
Charophyceae is a taxon of green algae whose exact rank is the matter of some current debate. Some botanists recommend expanding the existing plant kingdom to include charophyceans and chlorophytes while others consider Charophyceae to be a class within either the divisions Chlorophyta, Streptophytina, or Streptophyta. Other systematists classify Charophyceae as a class under division Charophyta, with Chlorophyta remaining a distinct division. [more]
At least 5,697 species and subspecies belong to the Class Charophyceae.
More info about the Class Charophyceae may be found here.