gametofity

Gametofity, or gametophytes, are the haploid multicellular stages in the plant life cycle that produce gametes by mitosis. They form part of the alternation of generations, alternating with the diploid sporophyte.

Among bryophytes—mosses, liverworts, and hornworts—the gametophyte is the dominant, photosynthetic generation, while the sporophyte is typically small, nutritionally dependent, and often short-lived.

In vascular plants, the sporophyte is the conspicuous generation, and the gametophyte is reduced. In seed plants, the male gametophyte is the pollen grain, and the female gametophyte develops within the ovule and is usually microscopic and dependent on sporophytic tissue.

Gametophytes arise from haploid spores produced by meiosis in the sporophyte. They bear the gametangia—antheridia that produce sperm and archegonia that produce eggs (in bryophytes and many ferns). Sperm typically require water to reach the egg, leading to fertilization that restarts the sporophyte generation.

Significance: the study of gametophytes illuminates plant reproduction, life-cycle evolution, and ecological strategies. The relative size and independence of the gametophyte versus sporophyte reflect deep evolutionary shifts from early land plants to modern seed plants.