Sporophyte

An independent sporophyte is the dominant form in all clubmosses, horsetails, ferns, gymnosperms, and angiosperms that have survived to the present day.

Early land plants had sporophytes that produced identical spores (isosporous or homosporous) but the ancestors of the gymnosperms evolved complex heterosporous life cycles in which the spores producing male and female gametophytes were of different sizes, the female megaspores tending to be larger, and fewer in number, than the male microspores.

[3] During the Devonian period several plant groups independently evolved heterospory and subsequently the habit of endospory, in which the gametophytes develop in miniaturized form inside the spore wall.

By contrast in exosporous plants, including modern ferns, the gametophytes break the spore wall open on germination and develop outside it.

The oocytes were fertilized in the archegonia by free-swimming flagellate sperm produced by windborne miniaturized male gametophytes in the form of pre-pollen.

Diagram showing the alternation of generations between a diploid sporophyte (bottom) and a haploid gametophyte (top)
Young sporophytes of the common moss Tortula muralis . In mosses, the gametophyte is the dominant generation, while the sporophytes consist of sporangium-bearing stalks growing from the tips of the gametophytes
Sporophytes of moss during spring
In flowering plants , the sporophyte comprises the whole multicellular body except the pollen and embryo sac
Cleistocarpous sporophyte of the moss Physcomitrella patens