gametophyte

[ guh-mee-tuh-fahyt, gam-i- ]

noun

, Botany.

1. the sexual form of a plant in the alternation of generations.

gametophyte

/ ɡəˈmiːtəʊˌfaɪt; ˌɡæmɪtəʊˈfɪtɪk /

noun

1. the plant body, in species showing alternation of generations, that produces the gametes Compare sporophyte

gametophyte

/ gə-mē′tə-fīt′ /

1. 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).
2. See more at alternation of generations

Derived Forms

• gametophytic, adjective

Other Words From

• ga·me·to·phyt·ic [g, uh, -mee-t, uh, -, fit, -ik, gam-i-], adjective

Word History and Origins

Origin of gametophyte¹

First recorded in 1890–95; gameto- + -phyte

A Closer Look

The evolution of plants has seen a steady reduction in the independence and size of the gametophyte generation when compared to the sporophyte generation. In the more primitive nonvascular plants, such as the mosses and liverworts, the gametophyte is the main plant form. It is relatively large and not dependent on the sporophyte for nutrition. In some species, the gametophytes are bisexual; in others, the sexes are separate. Female gametes remain in the gametophyte, where they are fertilized by sperm, usually from another gametophyte. The resultant embryos develop into sporophytes. These grow as smaller plants in or upon the gametophytes. The diploid sporophytes then produce haploid spores by meiosis, and these are dispersed and grow into new gametophytes. Among the vascular plants, however, the sporophyte is the larger plant form. For example, the familiar pine tree represents the diploid sporophyte generation. By meiosis, the pine eventually produces male and female gametophytes. The male gametophytes of the pine are small—they are the pollen grains released by male cones to be dispersed to female cones. The larger female gametophytes remain within the ovules of the female cones of the pine and are dependent on the surrounding sporophyte tissues for their nutrition. Each female gametophyte develops two egg cells, both of which are fertilized by a male gamete from a pollen grain. However, usually only one embryo will complete its development. This embryo is a new diploid sporophyte, housed within the developing pine seed. A pine seed thus contains three generations of the pine plant: the seed coat that arises from diploid tissue belonging to the ovule, the haploid gametophyte tissue that will serve as a food reserve for the embryo after germination, and the diploid embryo itself. In angiosperms, the female gametophyte has evolved into an even more reduced form. It consists of only the seven cells of the embryo sac.

Example Sentences

In liverworts like Marchantia, which lives in most soggy places worldwide, the gametophyte is the dominant phase – the thing you would think of as the plant.

From The Guardian

Old books teach that sperm and egg from a single gametophyte get together and create a new sporophyte, which grows into a mature fern.

From Washington Times

When water collects on this gametophyte, it releases amorous, mobile sperm cells that swim across the heart’s surface to fertilize the plant’s ovules, or eggs.

From New York Times

The lower half of the green thing in this picture is the tiny, gauzy fern gametophyte — the fern you don’t see:

From Scientific American

If you’ve eaten a pine nut, you’ve eaten the haploid female gametophyte of a pine tree, with a diploid embryonic sporophyte embedded inside — a deliciously oily polyploid sandwich.

From Scientific American