In plants that undergo
alternation of generations, a 'gametophyte' is the structure, or phase of life, that contains only half of the total complement of
chromosomes:
★ The
sporophyte produces
spores, in a process called
meiosis. These spores develop into a gametophyte. These spores and the resulting gametophyte have only half of the total complement of chromosomes.
★ The gametophyte produces male or female
gametes (or both), in a process called
mitosis.
The fusion of male and female gametes produces a
zygote which develops into the sporophyte.
In
mosses (
bryophytes) the gametophyte is the commonly known phase of the plant. An early developmental stage in the gametophyte of both mosses and
ferns (immediately following the
meiospore) is called the
Protonema.
In most other plants the gametophyte is very small (as in
ferns) or even reduced as in
flowering plants (angiosperms), where the female form (
ovule) is known as a 'megagametophyte' and the male form (
pollen) is called a 'microgametophyte'.
See also
★
Sporophyte
★
Alternation of generations
★
Archegonium
★
Antheridium