How To Use Megaspore In A Sentence
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They have male spores called microspores and female spores called megaspores.
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Meiosis results in the production of four megaspores, containing half the number of chromosomes of the sporophyte.
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In the ovules of most sexual flowering plants female gametogenesis is initiated from a single surviving gametic cell, the functional megaspore, formed after meiosis of the somatically derived megaspore mother cell (MMC) 1, 2.
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Microfossil assemblages from rare black and grey clays in this succession contain only a variety of seeds, Microcarpolithes hexagonalis and megaspores, and there are neither foraminifera nor other marine microfossils.
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Since the ‘seed habit’ begins with the reduction to a single functional megaspore in each megasporangium, heterospory seems like a logical intermediate step.
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Both of these genera are heterosporous, meaning that each species produces two distinctly different types of spores: microspores and megaspores.
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These, as in Gymnosperms, are of two kinds, microspores or pollen-grains, borne in the stamens (or microsporophylls) and megaspores, in which the egg-cell is developed, contained in the ovule, which is borne enclosed in the carpel (or megasporophyll).
Encyclopaedia Britannica, 11th Edition, Volume 2, Part 1, Slice 1
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Maternal apomictic embryos develop from a somatic cell within the ovule or from an unreduced embryo sac derived from the megaspore mother cell (diplospory).
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Both of these genera are heterosporous, meaning that each species produces two distinctly different types of spores: microspores and megaspores.
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They have male spores called microspores and female spores called megaspores.
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Microfossil assemblages from rare black and grey clays in this succession contain only a variety of seeds, Microcarpolithes hexagonalis and megaspores, and there are neither foraminifera nor other marine microfossils.
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During sexual megagametophytic development (with the embryo sac as the megagametophyte and the egg cell as megagamete), a sub-epidermal cell of the nucellus tissue differentiates into a megaspore-mother cell which undergoes meiosis I and II to form four megaspores.
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These, as in Gymnosperms, are of two kinds, microspores or pollen-grains, borne in the stamens (or microsporophylls) and megaspores, in which the egg-cell is developed, contained in the ovule, which is borne enclosed in the carpel (or megasporophyll).
Encyclopaedia Britannica, 11th Edition, Volume 2, Part 1, Slice 1
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Their heterosporous life cycle (including both megaspores and microspores) is likely to be an adaptation to their aquatic habit.
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Some of the large sphenophyte trees of the Paleozoic were heterosporous, producing large megaspores and small microspores, and probably retaining the megaspore in the strobilus.
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Both of these genera are heterosporous, meaning that each species produces two distinctly different types of spores: microspores and megaspores.
