Pseudosycidium The first of the charophytes, a distinct, new, evolutionary line of green algae which arose during the Silurian and whose method of reproduction was sexual. Well-developed male (antheridia) and female (oogonia) organs can be identified, the secretion of calcium carbonate around the female organs assisting preservation.

Pseudosycidium The first of the Charales, a distinct evolutionary line of green algae which arose during the Upper Silurian and whose method of reproduction was sexual. Well-developed male (antheridia) and female (oogonia) organs can be identified, the secretion of calcium carbonate around the female organs assisting preservation. See also CHAROPHYCEAE; and GYROGONITE.