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The sporophyte produces spores (hence the name) by meiosis, a process also known as "reduction division" that reduces the number of chromosomes in each spore mother cell by half. The resulting meiospores develop into a gametophyte. Both the spores and the resulting gametophyte are haploid, meaning they only have one set of chromosomes.
However, not all heteromorphic gametophytes come from heterosporous plants. That is, some plants have distinct egg-producing and sperm-producing gametophytes, but these gametophytes develop from the same kind of spore inside the same sporangium; Sphaerocarpos is an example of such a plant. In seed plants, the microgametophyte is called pollen.
Seed plant gametophytes are extremely reduced in size; the archegonium consists only of a small number of cells, and the entire male gametophyte may be represented by only two cells. [27] Differentiation of the spores. All spores the same size (homospory or isospory). Horsetails (species of Equisetum) have spores which are all of the same size ...
In exosporic species, the smaller spores germinate into free-living male gametophytes and the larger spores germinate into free-living female gametophytes. In endosporic species, the gametophytes of both sexes are very highly reduced and contained within the spore wall. The microspores of both exosporic and endosporic species are free-sporing ...
If the spores are deposited onto a suitable moist substrate they germinate to produce short, thin, free-living gametophytes called prothalli that are typically heart-shaped, small and green in color. The gametophytes produce both motile sperm in the antheridia and egg cells in separate archegonia. After rains or when dew deposits a film of ...
The sporophyte produces spore capsules , which are connected by stalks to the archegonia. The spore capsules produce spores by meiosis and when ripe the capsules burst open to release the spores. Bryophytes show considerable variation in their reproductive structures and the above is a basic outline.
In biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. [1] Spores form part of the life cycles of many plants , algae , fungi and protozoa . [ 2 ]
It is the biological process of gametogenesis during which cells that are haploid or diploid divide to create other cells. It can take place either through mitotic or meiotic division of diploid gametocytes into different cells depending on an organism's biological life cycle. For instance, gametophytes in plants undergo mitosis to produce gametes.