gamétophyte

Gametophyte is a term used in the life cycles of plants and algae that exhibit alternation of generations. It refers to the haploid stage of the organism, meaning it has only one set of chromosomes. The gametophyte's primary function is to produce gametes, which are reproductive cells such as sperm and eggs. These gametes are formed through mitosis.

In lower plants like mosses and liverworts, the gametophyte is the dominant and most visible generation. In contrast, in ferns and seed plants, the gametophyte is greatly reduced and dependent on the sporophyte generation. For example, in flowering plants, the female gametophyte is the embryo sac within the ovule, and the male gametophyte is contained within the pollen grain.

The fusion of two gametes, one from each parent, results in fertilization, which produces a diploid zygote. This zygote then develops into the sporophyte, the other generation in the alternation of generations. The sporophyte is the diploid stage and produces spores through meiosis. These spores then germinate and grow into new gametophytes, thus completing the life cycle. The alternation between the haploid gametophyte and the diploid sporophyte is a fundamental characteristic of plant reproduction.