Young sporophytes of the common moss Tortula muralis. Mosses are small soft Plants that are typically 1–10  cm (0 In mosses, the gametophyte is the dominant generation, while the sporophytes consist of sporangium-bearing stalks growing from the tips of the gametophytes

All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or alga that has a double set of chromosomes. In Plants and Algae that undergo Alternation of generations, a gametophyte is the multicellular structure or phase that is Haploid, containing Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms In Plants and Algae that undergo Alternation of generations, a gametophyte is the multicellular structure or phase that is Haploid, containing "Haplo" redirects here For the fictional character see The Death Gate Cycle. Plants are living Organisms belonging to the kingdom Plantae. A chromosome is an organized structure of DNA and Protein that is found in cells. A multicellular sporophyte generation or phase is present in the life cycle of all land plants and in some green algae. The Charales are Algae in the division Charophyta. They are green plants believed to be the closest relatives of the green land plants. For common flowering plants (Angiosperms), the sporophyte generation comprises almost their whole life cycle (i. The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group e. whole green plant, roots etc), except phases of small reproductive structures (pollen and ovule). Pollen is a fine to coarse powder consisting of microgametophytes ( pollen grains) which produce the male Gametes (sperm cells of Ovule literally means "small egg." In Seed plants the ovule is the structure that gives rise to and contains the female reproductive cells

The sporophyte produces spores (hence the name), by meiosis. In Biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions In Biology or life science meiosis (pronounced my-oh-sis is a process of reductional division in which the number of chromosomes per cell is cut in half These meiospores develop into a gametophyte. In Plants and Algae that undergo Alternation of generations, a gametophyte is the multicellular structure or phase that is Haploid, containing Both the spores and the resulting gametophyte are haploid, meaning they only have one set of homologous chromosomes. "Haplo" redirects here For the fictional character see The Death Gate Cycle. Homologous chromosomes are Chromosomes in a Biological cell that pair ( synapse) during Meiosis, or alternatively non-identical chromosomes that The mature gametophyte produces male or female gametes (or both) by mitosis. A gamete (from Ancient Greek γαμέτης; translated gamete = wife gametes = husband is a cell that fuses with another gamete Mitosis is the process in which a Eukaryotic cell separates the Chromosomes in its Cell nucleus, into two identical sets in two daughter nuclei The fusion of male and female gametes produces a diploid zygote which develops into a new sporophyte. Plant sexuality covers the wide variety of Sexual reproduction systems found across the Plant kingdom For other meanings see Zygote (disambiguation. A zygote (from Greek ζυγωτός zugōtos "joined" or "yoked" This cycle is known as alternation of generations or alternation of phases. The Alternation of phases (or generations) describes the life cycle of Plants Fungi and Protists A multicellular Diploid phase alternates

In flowering plants, the sporophyte comprises the whole multicellular body except the pollen and embryo sac

In the normal course of events, the zygote and sporophyte will have a full double set of chromosomes again. The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group Pollen is a fine to coarse powder consisting of microgametophytes ( pollen grains) which produce the male Gametes (sperm cells of Ovule literally means "small egg." In Seed plants the ovule is the structure that gives rise to and contains the female reproductive cells An exception is when a diploid and haploid gamete fuse, resulting in a triploid sporophyte, which will usually be sterile, as dividing three sets of chromosomes into two halves causes complications. "Haplo" redirects here For the fictional character see The Death Gate Cycle. "Haplo" redirects here For the fictional character see The Death Gate Cycle. Polyploidy occurs in cells and Organisms when there are more than two homologous sets of Chromosomes. A chromosome is an organized structure of DNA and Protein that is found in cells.

Bryophytes (mosses, liverworts and hornworts) have a dominant gametophyte stage on which the adult sporophyte is dependent on the gametophyte for nutrition. Bryophytes are all Embryophytes ('land Plants) that are non-vascular: they have tissues and enclosed reproductive systems but they lack Vascular tissue Mosses are small soft Plants that are typically 1–10  cm (0 This is an article about the non-vascular plants The name Hornwort is also often applied to an aquatic plant Ceratophyllum demersum in the family Ceratophyllaceae The embryo of the sporophyte develops from the zygote within the female sex organ or archegonium, and in its early development is therefore nurtured by the gametophyte. An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular An archegonium (pl archegonia) from the Ancient Greek ἀρχή ("beginning" and γόνος ("offspring" is a multicellular Because this embryo-nurturing feature of the life cycle is common to all land plants they are known collectively as the Embryophytes. The embryophytes are the most familiar group of Plants They include Trees Flowers Ferns Mosses and various other green

Most algae have dominant gametophyte generations, but in some species the gametophytes and sporophytes are morphologically similar (isomorphic). Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms In Abstract algebra, an isomorphism ( Greek: ἴσος isos "equal" and μορφή morphe "shape" is a bijective An independent sporophyte is the dominant form in all clubmosses, horsetails, ferns, gymnosperms, and angiosperms (flowering plants) that have survived to the present day. Lycopodiopsida is a class of plants often loosely grouped as the fern allies, and includes the clubmosses Equisetum is a genus of Vascular plants that reproduce by spores rather than seeds A fern is any one of a group of about 20000 Species of Plants classified in the phylum or division Pteridophyta, also known as Filicophyta Gymnosperm (Gymnospermae are a group of Spermatophyte seed-bearing Plants with Ovules on the edge or blade of an open Sporophyll, which are The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group 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. Megaspores, also called macrospores, are a type of spores that is present in Heterosporous Plants These types of plants have two spore types megaspores In Biology, a microspore is a small Spore as contrasted to the larger megaspore.

During the Devonian period several plant groups independently evolved heterospory and subsequently the habit of endospory, in which single megaspores were retained within the sporangia of the parent sporophyte, instead of being freely liberated into the environment as in ancestral exosporous plants. The Devonian is a geologic period and system of the Paleozoic era spanning from to  million years ago. Heterospory is the production of Spores of two different sizes and sexes by the Sporophytes of Land plants Heterospory was evolved from Isospory These endosporic megaspores contained within them a miniature multicellular female gametophyte complete with female sex organs or archegonia containing oocytes which were fertilised by free-swimming sperm produced by windborne miniatuarised male gametophytes in the form of pre-pollen. An archegonium (pl archegonia) from the Ancient Greek ἀρχή ("beginning" and γόνος ("offspring" is a multicellular An oocyte, ovocyte, or rarely ocyte, is a female Gametocyte or Germ cell involved in reproduction. The term sperm is derived from the Greek word (σπέρμα sperma (meaning "seed" and refers to the male reproductive cells. Pollen is a fine to coarse powder consisting of microgametophytes ( pollen grains) which produce the male Gametes (sperm cells of The resulting zygote developed into the next sporophyte generation while still retained within the pre-ovule, the single large female meiospore or megaspore contained in the modified sporangium or nucellus of the parent sporophyte. For other meanings see Zygote (disambiguation. A zygote (from Greek ζυγωτός zugōtos "joined" or "yoked" Ovule literally means "small egg." In Seed plants the ovule is the structure that gives rise to and contains the female reproductive cells Megaspores, also called macrospores, are a type of spores that is present in Heterosporous Plants These types of plants have two spore types megaspores A sporangium (pl sporangia) is a Plant or fungal structure producing and containing Spores Sporangia occur in angiosperms, Ovule literally means "small egg." In Seed plants the ovule is the structure that gives rise to and contains the female reproductive cells The evolution of heterospory and endospory were among the earliest steps in the evolution of seeds of the kind produced by gymnosperms and angiosperms today. A seed (in some plants referred to as a kernel) is a small embryonic Plant enclosed in a covering called the seed coat usually with some stored Gymnosperm (Gymnospermae are a group of Spermatophyte seed-bearing Plants with Ovules on the edge or blade of an open Sporophyll, which are The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group

References

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• T. N. Taylor, H. Kerp and H. Hass (2005) Life history biology of early land plants: Deciphering the gametophyte phase. Proceedings of the National Academy of Sciences 102, 5892-5897.
• P. R. Bell & A. R. Helmsley (2000) Green plants. Their Origin and Diversity. Cambridge University Press ISBN 0 521 64673 1