Alternation of generations

A life cycle in which multicellular haploid and diploid stages alternate. The haploid stage produces gametes, while the diploid stage produces spores by meiosis.

Sporophyte: The multicellular diploid stage of a plant or alga that produces haploid spores by meiosis. It begins the diploid half of the cycle by making spores.
Moss: A small nonvascular land plant whose conspicuous leafy body is haploid. In mosses, the gametophyte dominates and the sporophyte remains attached to it.
Haplontic life cycle: A life cycle in which the organism is mainly haploid and the zygote is the only diploid stage. Unlike alternation of generations, it has no multicellular diploid generation.
Haploid: A cell or organism with one complete set of chromosomes. The gametophyte is multicellular and haploid.
Gametophyte: The multicellular haploid stage of a plant or alga that produces gametes by mitosis. It forms the haploid half of the cycle and makes gametes.
Fern: A vascular plant that reproduces by spores and has a conspicuous leafy sporophyte. Ferns show a dominant sporophyte alongside a small, independent gametophyte.
Diplontic life cycle: A life cycle in which the organism is mainly diploid and the haploid stage consists only of gametes. It lacks a multicellular haploid generation.
Diploid: A cell or organism with two complete sets of chromosomes, typically one from each parent. The sporophyte is multicellular and diploid.
Meiosis: A cell division that reduces chromosome number by half and produces genetically varied cells. It changes the diploid sporophyte’s chromosome number to produce haploid spores.
Flowering plant: A plant that produces flowers and encloses seeds within fruits. Its gametophytes are highly reduced and develop within sporophyte tissues.

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