The
sporophyte develops from the union of two
gametes, such as an
egg fertilized by a
sperm; in turn, the
sporophyte forms
spores that develop into
gametophytes. The alternation
between haploid (gametophyte) and
diploid (sporophyte) phases, known as
alternation of generations, occurs in all multicellular
plants. As plants advanced in
evolutionary development, the sporophyte became the increasingly
dominant plant form and the gametophyte form has been correspondingly
reduced.
In contrast to mosses, for example, in the advanced
angiosperms the male and
female gametophytes are reduced
to three-celled and seven-celled structures, respectively, found within
the reproductive organs of the
familiar flowering plant
(the sporophyte). |
