Gametes are produced by mitosis, not meiosis, in these organisms as they are comprised of haploid cells. This type of life cycle includes both diploid and haploid multicellular stages. The multicellular diploid stage is called a sporophyte and meiosis in this stage produces haploid cells called spores . The spore divides mitotically to generate a multicellular haploid stage called a gametophyte . Gametes are produced from the haploid gametophyte by mitosis.
Fertilization produces a diploid zygote which develops into the next sporophyte generation.
In this type of life cycle, sporophyte and gametophyte generations take turns reproducing each other.