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Gymnosperms


The progymnosperms are an extinct group of free-sporing (nonseed) plants that have fern-like leaves and reproductive structures attached to gymnosperm-like stems with large amounts of wood.
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Gymnosperms
Fossil from the Devonian period reveal fernlike plants that were heterosporous; that is, produced two kinds of spores.
microspores (male) and
megaspores (female).
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gymnosperms: vascular plants having naked seeds, such as the conifers.
H
haploid: cells containing one copy of each chromosome.
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Gymnosperms (especially conifers, Bennettitales and cycads) and ferns common. Many types of dinosaurs, such as sauropods, carnosaurs, and stegosaurs. Mammals common but small. First birds and lizards. Ichthyosaurs and plesiosaurs diverse.
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Early seed plants are referred to as gymnosperms (naked seeds), as the seed embryo is not enclosed in a protective structure at pollination, with the pollen landing directly on the embryo.
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Life on Earth continued to evolve, and in the late Paleozoic, gymnosperms appeared. By the Triassic Period (245-208 mya), gymnosperms dominated the Earth's forests.
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Angiosperms evolved from gymnosperms, their closest relatives are Gnetae. Two key adaptations allowed them to displace gymnosperms as the dominant fauna -- fruits and flowers.
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seed plant Common term for gymnosperms and angiosperms.
seed-scale complex The spirally arranged scales on a female strobilus in gymnosperms.
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The female sex organ of liverworts, mosses, ferns, and most gymnosperms. It is usually a flask-shaped organ, comprising a swollen base or venter containing a single egg-cell and a slender elongated neck containing one or more layers of cells.
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Transfer of pollen from the anther to the stigma in angiosperms or from the microsporangium to the micropyle in gymnosperms.
Clone bank
See genomic library.
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Pollen another name for the male gametophyte in gymnosperms and angiosperms
(pollen = fine flour) ...
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in the sperm plants (
Spermatophyta
) division. Examples are cycad, conifer and gingko. Cycads are the most primitive ones evolved in the Devonian period about 400
Mya
. There are about 700 extant species in Gymnosperms.
Link to a lecture on ...
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