In the details of sperm ultrastructure, charophytes are more similar to plants than to other green algae. Genetic relationship - Nonvascular plant nuclear genes and ribosomal RNA most closely resemble those of charophytes. Scientists also believe that living in shallow water was a preadaptation to living on land. Waxy cuticles and jacketed organs, both characteristics of nonvascular plants, are possible adaptations that the algae developed to survive in these conditions. Reproduction Nonvascular plants can reproduce both sexually and asexually.
Asexual reproduction is the less common method.
It basically consists of the regeneration of plant material, leaves or other parts, that fall to the ground and generate secondary plants which bear new buds. Most nonvascular plants, though, reproduce sexually. Their gametes develop within structures called gametangia, which are organs that have protective jackets of sterile cells that prevent the gametes from drying out during development. The male gametangium is called the antheridium, and it produces flagellated sperm. As in algae, the flagellated sperm require water to swim from the antheridium to the archegonium and fertilize the egg.