Non-Vascular Plants
These plants evolved earliest in the Plant Kingdom. Unlike other plants, Non-vascular plants never develop vascular tissue. As a result non-vascular plants are usually restricted to a small size and to moist areas.
Mosses and other non-Vascular Plants exist mostly in the haploid gametophyte stage. Egg and sperm are created by mitosis in the archegonia and antheridia of the gametophyte, respectively. When water is present because of rain or dew, the flagellated sperm swim from the antheridia into the archegonia. Once their sperm and egg fuse together to form a diploid zygote. The zygote matures into the sporophyte generation of mosses which is dependent upon the gametophyte. Within the sporangium, a structure of the sporophyte, haploid spores are produced by meiosis. When the spores are released to the wind and land in a suitable location they will begin to germinate and grow into the gametophyte stage, thus restarting the cycle