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sporophyll

sporophyll

sporophyll Sentence Examples

  • In GY~~1NospERMsso-called because the ovules (and seeds) are borne on an open sporophyll or carpelthe microsporophylls and macrosporophylls are not as a rule associated in the same shoot and are generally arranged in cone-like structures; one or two small prothallial cells are formed in the germination of the microspore; the male cells are in some older members of the group motile though usually passive.

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  • Metamorphosis.It has already been pointed out that each kind of member of the body may present a variety of forms. For example, a stem may be a tree-trunk, or a twining stem, or a tendril, or a thorn, or a creeping rhizome, or a tuber; a leaf may be a green foliage-leaf, or a scale protecting a bud, or a tendril, or a pitcher, or a floral leaf, either sepal, petal, stamen or carpel (sporophyll); a root may be a fibrous root, or a swollen tap-root like that of the beet or the turnip. All these various forms are organs discharging some special function, and are examples of what Wolff called modification, and Goethe metamorphosis.

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  • Flora), the primitive leaf was a reproductive leaf, a sporophyll, from which the foliage-leaf was derived by progressive sterilization.

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  • It was formerly assumed, and the view is still held, that the foliage-leaf was the primitive form from which all others were derived, mainly on the ground that, in ontogeny, the foliage-leaf generally precedes the sporophyll.

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  • There is thus a considerable body of evidence to support Bowers view of the primitive nature of the sporophyll.

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  • In Sphenophyllum fertile both the ventral lobes of the sporophyll (corresponding to the sporangiophores in other species) and the dorsal lobes, which in other species are sterile, were developed as peltate sporangiophores.

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  • The sporangia of the Psilotaceae are associated in synangia, which occupy the same position relatively to the sporophyll, as the single sporangium of Lycopodium or the group of sporangia in Spenophyllum majus.

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  • H, Sporophyll bearing the single sporangium on its upper surface.

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  • A single sporangium is borne on the axis just above the insertion of each sporophyll.

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  • The cones, which in some instances at least were heterosporous, presented a general resemblance to those of Lycopodium and Selaginella, a single sporangium being situated on the upper surface of each sporophyll.

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  • The recently discovered species, Sphenophyllum fertile, while resembling Bowmanites Romeri in its peltate, bisporangiate sporangiophores, is peculiar in the fact that both dorsal and ventral lobes of the sporophyll were fertile, dividing in a palmate manner into several branches, each of which constitutes a sporangiophore.

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  • lq The sporophyll, usually almost horizontal in position, has an upturned lamina beyond the sporangium, and a shorter dorsal lobe, so that the form of the whole is somewhat peltate.

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  • The genus Spencerites (Lower Coal Measures) differs from Lepidostrobus mainly in the insertion of the sporangium, which, instead of being attached along the whole upper surface of the sporophyll, was connected with an outgrowth on its upper surface by a small neck of tissue towards the distal end.

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  • The Sigillariae, like the (X about 12.) Lepidodendra, were large trees, but must cu, Lateral cushions on have differed from those of the previous sporophyll.

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  • sph, Sporophyll.

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  • (X about 30.) 1, Lamina of sporophyll.

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  • In GY~~1NospERMsso-called because the ovules (and seeds) are borne on an open sporophyll or carpelthe microsporophylls and macrosporophylls are not as a rule associated in the same shoot and are generally arranged in cone-like structures; one or two small prothallial cells are formed in the germination of the microspore; the male cells are in some older members of the group motile though usually passive.

    0
    0
  • Metamorphosis.It has already been pointed out that each kind of member of the body may present a variety of forms. For example, a stem may be a tree-trunk, or a twining stem, or a tendril, or a thorn, or a creeping rhizome, or a tuber; a leaf may be a green foliage-leaf, or a scale protecting a bud, or a tendril, or a pitcher, or a floral leaf, either sepal, petal, stamen or carpel (sporophyll); a root may be a fibrous root, or a swollen tap-root like that of the beet or the turnip. All these various forms are organs discharging some special function, and are examples of what Wolff called modification, and Goethe metamorphosis.

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    0
  • Flora), the primitive leaf was a reproductive leaf, a sporophyll, from which the foliage-leaf was derived by progressive sterilization.

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    0
  • It was formerly assumed, and the view is still held, that the foliage-leaf was the primitive form from which all others were derived, mainly on the ground that, in ontogeny, the foliage-leaf generally precedes the sporophyll.

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    0
  • There is thus a considerable body of evidence to support Bowers view of the primitive nature of the sporophyll.

    0
    0
  • In Sphenophyllum fertile both the ventral lobes of the sporophyll (corresponding to the sporangiophores in other species) and the dorsal lobes, which in other species are sterile, were developed as peltate sporangiophores.

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    0
  • The sporangia of the Psilotaceae are associated in synangia, which occupy the same position relatively to the sporophyll, as the single sporangium of Lycopodium or the group of sporangia in Spenophyllum majus.

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  • H, Sporophyll bearing the single sporangium on its upper surface.

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    0
  • A single sporangium is borne on the axis just above the insertion of each sporophyll.

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    0
  • The cones, which in some instances at least were heterosporous, presented a general resemblance to those of Lycopodium and Selaginella, a single sporangium being situated on the upper surface of each sporophyll.

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    0
  • The recently discovered species, Sphenophyllum fertile, while resembling Bowmanites Romeri in its peltate, bisporangiate sporangiophores, is peculiar in the fact that both dorsal and ventral lobes of the sporophyll were fertile, dividing in a palmate manner into several branches, each of which constitutes a sporangiophore.

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  • lq The sporophyll, usually almost horizontal in position, has an upturned lamina beyond the sporangium, and a shorter dorsal lobe, so that the form of the whole is somewhat peltate.

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  • The genus Spencerites (Lower Coal Measures) differs from Lepidostrobus mainly in the insertion of the sporangium, which, instead of being attached along the whole upper surface of the sporophyll, was connected with an outgrowth on its upper surface by a small neck of tissue towards the distal end.

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  • An integument grew up from the superior surface of the sporophyll, completely enveloping the sporangium, except for a narrow crevice left open along the top. In favourable cases the prothallus is found preserved, within the functional megaspore or embryo-sac, and the whole appearance, especially as seen in a section tangential to the strobilus, is then remarkably seed-like (see diagram, fig.

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  • Each sporophyll bears a megasporangium, attached to its upper surface at the proximal end, containing a single large megaspore (fig.

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  • The Sigillariae, like the (X about 12.) Lepidodendra, were large trees, but must cu, Lateral cushions on have differed from those of the previous sporophyll.

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  • sph, Sporophyll.

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  • (X about 30.) 1, Lamina of sporophyll.

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  • Numerous pairs of pinnules are attached to the rachis of each sporophyll, and the larger pinnules bear 20 to 30 synangia (sori or plurilocular sporangia) (fig.

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