- the sexual form of a plant in the alternation of generations.
- the plant body, in species showing alternation of generations, that produces the gametesCompare sporophyte
- Among organisms which display an alternation of generations as part of their life cycle (such as plants and certain algae), the haploid organism that produces gametes. Each of its cells has only one, unpaired set of chromosomes, as opposed to the corresponding diploid form of the organism, called the sporophyte. A gametophyte develops from spores produced by the sporophyte. The gametophytes of homosporous plants are bisexual (produce both eggs and sperm), while the gametophytes of heterosporous plants, such as all seeds plants, are unisexual (produce only eggs or only sperm). See more at alternation of generations sporophyte.