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Diagram showing the alternation of generations between a diploid sporophyte (bottom) and a haploid gametophyte (top) A sporophyte (/ ˈ s p ɔːr. ə ˌ f aɪ t /) is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
The last stage of the moss lifecycle is shown, where the sporophytes are visible before dispersion of their spores: the calyptra (1) is still attached to the capsule (3). The tops of the gametophytes (2) can be discerned as well. Inset shows the surrounding, black poplars growing on sandy loam on the bank of a kolk, with the detail area marked.
The 'alternation of generations' in the life cycle is thus between a diploid (2n) generation of multicellular sporophytes and a haploid (n) generation of multicellular gametophytes. [17] Gametophyte of the fern Onoclea sensibilis (flat thallus, bottom) with a descendant sporophyte beginning to grow from it (small frond, top)
In meiotic sporogenesis, a diploid spore mother cell within the sporangium undergoes meiosis, producing a tetrad of haploid spores. In organisms that are heterosporous, two types of spores occur: Microsporangia produce male microspores, and megasporangia produce female megaspores. In megasporogenesis, often three of the four spores degenerate ...
Some liverworts, such as Marchantia, have a cuticle, and the sporophytes of mosses have both cuticles and stomata, which were important in the evolution of land plants. [ 3 ] All land plants have a life cycle with an alternation of generations between a diploid sporophyte and a haploid gametophyte , but in all non-vascular land plants, the ...
Moss sporangia (the capsule and the stalk/seta make up the diploid asexual sporophyte generation) [6] In mosses, liverworts and hornworts, an unbranched sporophyte produces a single sporangium, which may be quite complex morphologically.
The microspore has three different types of wall layers. The outer layer is called the perispore, the next is the exospore, and the inner layer is the endospore.The perispore is the thickest of the three layers while the exospore and endospore are relatively equal in width.
The life cycle of a gymnosperm involves alternation of generations, with a dominant diploid sporophyte phase, and a reduced haploid gametophyte phase, which is dependent on the sporophytic phase. [4] The term "gymnosperm" is often used in paleobotany to refer to (the paraphyletic group of) all non-angiosperm seed plants.