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The sporophyte develops from the zygote produced when a haploid egg cell is fertilized by a haploid sperm and each sporophyte cell therefore has a double set of chromosomes, one set from each parent. All land plants , and most multicellular algae, have life cycles in which a multicellular diploid sporophyte phase alternates with a multicellular ...
The haploid prothallus does not resemble the sporophyte, and as such ferns and their allies have a heteromorphic alternation of generations. The prothallus is short-lived, but carries out sexual reproduction, producing the diploid zygote that then grows out of the prothallus as the sporophyte.
The sporophyte of a flowering plant is often described using sexual terms (e.g. "female" or "male") based on the sexuality of the gametophyte it gives rise to. For example, a sporophyte that produces spores that give rise only to male gametophytes may be described as "male", even though the sporophyte itself is asexual, producing only spores.
Heterospory stops self-fertilization from occurring in a gametophyte, but does not stop two gametophytes that originated from the same sporophyte from mating. [8] This specific type of self-fertilization is termed as sporophytic selfing, and in extant plants it occurs most commonly among angiosperms .
The mature sporophyte produces spores by meiosis, sometimes referred to as reduction division because the chromosome pairs are separated once again to form single sets. In mosses and liverworts, the gametophyte is relatively large, and the sporophyte is a much smaller structure that is never separated from the gametophyte.
Two gametes fuse to form a zygote, which develops into a new sporophyte. This cycle is known as alternation of generations . The spores of seed plants are produced internally, and the megaspores (formed within the ovules) and the microspores are involved in the formation of more complex structures that form the dispersal units, the seeds and ...
In the bryophytes the sporophyte remains dependent on the gametophyte, while in all other embryophytes the sporophyte generation is dominant and capable of independent existence. Embryophytes also differ from algae by having metamers. Metamers are repeated units of development, in which each unit derives from a single cell, but the resulting ...
The sporophyte lacks an apical meristem, an auxin-sensitive point of divergence with other land plants some time in the Late Silurian/Early Devonian. [17] [18] When the sporophyte is mature, it has a multicellular outer layer, a central rod-like columella running up the center, and a layer of tissue in between that produces spores and pseudo ...