Gametophyte

A gametophyte is the haploid, gamete-producing stage in the life cycle of plants and many algae. It develops from a spore and produces gametes by mitosis.

Alternation of generations: A life cycle that alternates between multicellular haploid and diploid stages. The gametophyte is the haploid half of this recurring life cycle.
Meiosis: Cell division that halves chromosome number and produces genetically varied cells. Meiosis makes spores in the sporophyte generation, unlike gametophyte mitosis.
Haploid: Having one complete set of chromosomes in a cell. A gametophyte's cells have one chromosome set.
Pollen tube: A tube grown by a pollen grain that carries sperm cells toward an ovule. It delivers male gametes from the seed-plant gametophyte to the egg.
Spore: A reproductive cell that can develop into a new organism without fusing with another cell. A haploid spore grows into the gametophyte.
Moss: A small, nonvascular land plant whose conspicuous life stage is the gametophyte. In mosses, the independent gametophyte dominates the visible plant body.
Diploid: Having two complete sets of chromosomes in a cell. The diploid sporophyte alternates with the haploid gametophyte.
Embryo sac: The female gametophyte inside a flowering plant's ovule. It contains the egg and central cell involved in double fertilization.
Mitosis: Cell division that produces daughter cells with the same chromosome number as the parent cell. The haploid gametophyte makes gametes through mitosis, not meiosis.
Fern: A seedless vascular plant that reproduces by spores and has a small gametophyte. Fern gametophytes are separate, usually small plants beneath conspicuous sporophytes.

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