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(also Charophyceae), a phylum of algae or, according to some classifications, a class of green algae. The plants reach 1 m in height and have lateral branches that depart in whorls from multicellular nodes. Each internode consists of one cell, which may become overgrown by a bark of narrow cells that grow upward and downward from the nodes. The cell membranes are sometimes calcified. The lower parts, which are submerged in mud or sand, are colorless and have rhizoids. Vegetative reproduction occurs from various parts of the algae and from unicellular or multicellular tubercles formed on shoots in the ground. Asexual reproduction by spores is absent. The organs of sexual reproduction are multicellular: the oogoniums (spore buds), with one egg cell, and the antheridia. Fertilization occurs on the maternal plant; meiosis occurs when the oogonium sprouts, with three nuclei out of four being destroyed.
There are 300 species, making up six genera. The USSR has 45 species. The algae grow in freshwaters and in areas of seas with decreased salinity. They have the property of softening hard water. Charophyta are known in fossil form from the Devonian.