Flexi Says: Mosses undergo sexual reproduction. In mosses, male reproductive organs, called antheridia (singular, antheridium), produce motile sperm with two flagella. Female reproductive organs, called archegonia (singular, archegonium), produce eggs. In order for fertilization to occur, sperm must swim in a drop of water from an antheridium to an egg in an archegonium. If fertilization takes place, it results in a zygote that develops into a tiny sporophyte on the parent gametophyte plant. The sporophyte produces haploid spores, and these develop into the next generation of gametophyte plants. Then the cycle repeats.