Microsporangium | plant anatomy | Britannica (original) (raw)

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• function in plant reproduction
  • 
    In plant: Heterosporous life histories
    Microsporangia (male sporangia) produce microsporocytes (micromeiocytes) that yield microspores. Megasporangia (female sporangia) produce megasporocytes (megameiocytes) that yield megaspores. The sporangia may be borne in specialized structures such as sori in ferns, cones (strobili) in some pteridophytes and most gymnosperms, or flowers in angiosperms.
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  • 
    In plant reproductive system: Lycopsids
    …megaspores, and microsporophylls that contain microsporangia, which will yield microspores. Although the evolutionary origin of two kinds of spores (dimorphism) is unknown, the development of megaspores in living plants suggests that differences in nutrition in the two kinds of sporangia are significant. In a microsporangium, most of the microsporocytes undergo…
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structure of

angiosperms

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  In angiosperm: The androecium
  …in terminal saclike structures (microsporangia) called anthers. The number of stamens comprised by the androecium is sometimes the same as the number of petals, but often the stamens are more numerous or fewer in number than the petals. There are generally two pairs of spore-containing sacs (microsporangia) in a…
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• flowers
  • 
    In flower: Pollination
    The stamen bears microsporangia (spore cases) in which are developed numerous microspores (potential pollen grains); the pistil bears ovules, each enclosing an egg cell. When a microspore germinates, it is known as a pollen grain. When the pollen sacs in a stamen’s anther are ripe, the anther releases…
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gymnosperms

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  In gymnosperm: General features
  Microsporangia, or pollen sacs, are borne on the lower surfaces of the microsporophylls. The number of microsporangia may vary from two in many conifers to hundreds in some cycads. Within the microsporangia are cells which undergo meiotic division to produce haploid microspores.
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• conifers

  • 
    In conifer: Strobili
    …all conifers the organs containing microsporangia (“male”) are separate from those bearing megasporangia (“female”), and in Cephalotaxus, some junipers (Juniperus), and the family Taxaceae they are found on different individuals.
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• cycadophytes

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    In cycadophyte: Sporophyte phase
    …bearing large pollen sacs (microsporangia) in clusters (sori) on their lower (abaxial) surfaces. Up to 200 cubic cm (12 cubic inches) of pollen are produced by a single cone of Cycas rumphii, and some other species produce similar volumes. It was once estimated that one pollen cone of _Encephalartos_…
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• gnetophytes

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    In gnetophyte: Reproductive structures and function
    …a cluster of sporangia, called microsporangia, that house the haploid reproductive cells (spores). The microsporangia are surrounded by a pair of bracteoles (scalelike leaves). Meiotic divisions in cells of the microsporangia produce the haploid pollen grains.
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• lycophytes

  • 
    In lycophyte: Life cycle
    …two types of sporangia, called microsporangia and megasporangia; the sporophylls associated with them are termed microsporophylls and megasporophylls.
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