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Information about Sporophyte

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Young sporophytes of the common hair cap moss (Polytrichum commune). In mosses, the gametophyte is the dominant generation, while the sporophytes consist of sporangium-bearing stalks growing from the tips of the gametophytes
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In flowering plants, the sporophyte comprises the whole multicellular body except the pollen and embryo sac
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. A multicellular sporophyte generation or phase is present in the life cycle of all land plants and in some green algae. For common flowering plants (Angiosperms), the sporophyte generation comprises almost their whole life cycle (i.e. whole green plant, roots etc), except phases of small reproductive structures (pollen and ovule).

The sporophyte produces spores (hence the name), by meiosis. These meiospores develop into a gametophyte. Both the spores and the resulting gametophyte are haploid, meaning they only have one set of homologous chromosomes. The mature gametophyte produces male or female gametes (or both) by mitosis. The fusion of male and female gametes produces a zygote which develops into a new sporophyte. This cycle is known as alternation of generations or alternation of phases.

In the normal course of events, the zygote and sporophyte will have a full double set of chromosomes again. 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.

Bryophytes (mosses, liverworts and hornworts) have a dominant gametophyte stage on which the adult sporophyte is parasitic. 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. Because this embryo-nurturing feature of the life cycle is common to all land plants they are known collectively as the Embryophytes.

Most algae have dominant gametophyte generations, but in some species the gametophytes and sporophytes are morphologically similar (isomorphic). An independent sporophyte is the dominant form in all clubmosses, horsetails, ferns, gymnosperms, and angiosperms (flowering plants) 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.

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. 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. 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. 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.

References

  • P. Kenrick & P.R. Crane (1997) The origin and early evolution of plants on land. Nature 389, 33-39.
  • 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

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Botany
Subdisciplines of botanyEthnobotany Paleobotany Plant anatomy Plant ecology Plant morphology Plant physiology
PlantsEvolutionary history of plants Algae Bryophyte Pteridophyte Gymnosperm Angiosperm
Plant partsFlower Fruit Leaf Meristem Root Stem Stoma Vascular tissue Wood
Plant cellsCell wall Chlorophyll Chloroplast Photosynthesis Plant hormone Plastid Transpiration
Plant life cyclesGametophyte Plant sexuality Pollen Pollination Seed Spore Sporophyte
Botanical nomenclatureBotanical name Herbarium IAPT ICBN Species Plantarum
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phytoplankton — provide the food base for most marine food chains. In very high densities (so-called algal blooms) these algae may discolor the water and outcompete or poison other life forms.
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In plants that undergo alternation of generations, a gametophyte is the structure, or phase of life, that contains only half of the total complement of chromosomes:
  • The sporophyte produces spores, in a process called meiosis. These spores develop into a gametophyte.

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Plantae
Haeckel, 1866[1]

Divisions

Green algae
  • Chlorophyta
  • Charophyta
Land plants (embryophytes)
  • Non-vascular land plants (bryophytes)

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Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division.]] A chromosome is a single large macromolecule of DNA, and constitutes a physically organized form of DNA in a cell.
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Charales

Family: Characeae

Genera

Chara
Lamprothamnium
Nitella
Tolypella

The Charales are an in the order Charales of green alga, Chlorophyta.
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Magnoliophyta

Classes

Magnoliopsida - Dicots
Liliopsida - Monocots

The flowering plants or angiosperms are the most widespread group of land plants. The flowering plants and the gymnosperms comprise the two extant groups of seed plants.
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Pollen is a fine to coarse powder consisting of microgametophytes (pollen grains), which produce the male gametes (sperm cells) of seed plants. The pollen grain with its hard coat protects the sperm cells during the process of their movement between the stamens
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Ovule literally means "small egg." In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integuments forming its outer layer, the nucellus
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spore is a reproductive structure that is adapted for dispersion and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many plants, algae, fungi and some protozoans.
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meiosis (IPA: /maɪˈəʊsɪs/) is the process by which one diploid eukaryotic cell divides to generate four haploid cells often called gametes.
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In plants that undergo alternation of generations, a gametophyte is the structure, or phase of life, that contains only half of the total complement of chromosomes:
  • The sporophyte produces spores, in a process called meiosis. These spores develop into a gametophyte.

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Homologous chromosomes are chromosomes in a biological cell that pair (synapse) during meiosis, or alternatively, non-identical chromosomes that contain information for the same biological features and contain the same genes at the same loci but possibly different genetic
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A gamete (from Ancient Greek γαμετης; translated gamete = wife, gametes = husband) is a cell that fuses with another gamete during fertilisation (conception) in organisms that reproduce sexually.
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Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants.
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For other meanings see Zygote (disambiguation).
A zygote (Greek: ζυγωτόν) is a cell that is the result of fertilization.
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Alternation of generations is a reproductive cycle of certain plants, fungi, and protists. The term is a bit confusing for people familiar only with the life cycle of a typical animal.
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Polyploidy is the condition of some biological cells and organisms manifested by the presence of more than two homologous sets of chromosomes. Polyploid types are termed according to the number of chromosome sets in the nucleus: triploid (three sets; 3x),
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Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division.]] A chromosome is a single large macromolecule of DNA, and constitutes a physically organized form of DNA in a cell.
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The bryophytes are those embryophytes ('land plants') that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither flower nor produce seeds, reproducing via spores.
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MOSS may refer to:
  • Market Oriented Sector Selective talks, trade negotiations held between the United States and Japan in 1984
  • Microsoft Office SharePoint Server 2007, the current version of what used to be known as SharePoint Portal Server

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Liverwort may refer to either
  • Marchantiophyta, a division of non-vascular plants.
  • Hepatica, a genus of spring flowers.

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Anthocerotophyta

Class: Anthocerotopsida

Families & Genera

Leiosporocerotaceae
  • Leiosporoceros
Anthocerotaceae
  • Anthoceros
  • Folioceros

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An archegonium (pl: archegonia), from the ancient Greek αρχη (beginning) and γονος (offspring), is a multicellular structure or organ of the gametophyte phase of certain plants producing and containing the ovum
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Embryophyta

Divisions
  • Non-vascular land plants (bryophytes)
  • Marchantiophyta - liverworts
  • Anthocerotophyta - hornworts

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phytoplankton — provide the food base for most marine food chains. In very high densities (so-called algal blooms) these algae may discolor the water and outcompete or poison other life forms.
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In mathematics, an isomorphism (Greek: isos "equal", and morphe "shape") is a bijective map f such that both f and its inverse f −1 are homomorphisms, i.e., structure-preserving mappings.
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Lycopodiopsida

Orders
  • Lycopodiales
  • Family Lycopodiaceae
  • Family Huperziaceae
  • Drepanophycales †
Lycopodiopsida
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Equisetaceae

Genus: Equisetum

Species
See text

Equisetum is a genus of vascular plants that reproduce by spores rather than seeds.
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