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Moss leaf under microscope, showing gemmae and a hair point (40x) Moss gametophytes have stems which may be simple or branched and upright (acrocarp) or prostrate (pleurocarp). The early divergent classes Takakiopsida, Sphagnopsida, Andreaeopsida and Andreaeobryopsida either lack stomata or have pseudostomata that do not form pores.
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)
However, the female gametophytes of Ginkgo biloba do contain chlorophyll and can produce some of their own energy, though, not enough to support itself without being supplemented by the sporophyte. [15] The female gametophyte forms from a diploid megaspore that undergoes meiosis and starts being singled celled. [16]
Young sporophytes of the common moss Tortula muralis. In mosses, the gametophyte is the dominant generation, while the sporophytes consist of sporangium-bearing stalks growing from the tips of the gametophytes Sporophytes of moss during spring In flowering plants, the sporophyte comprises the whole multicellular body except the pollen and ...
In all bryophytes, the primary plants are the haploid gametophytes, with the only diploid portion being the attached sporophyte, consisting of a stalk and sporangium. Because these plants lack lignified water-conducting tissues, they cannot become as tall as most vascular plants. Algae, especially green algae. The algae consist of several ...
Sporophytes produce haploid spores by meiosis, that grow into gametophytes. Bryophytes are gametophyte dominant, [11] meaning that the more prominent, longer-lived plant is the haploid gametophyte. The diploid sporophytes appear only occasionally and remain attached to and nutritionally dependent on the gametophyte. [12]
Protonematal cells of the moss Physcomitrella patens. A protonema (plural: protonemata) is a thread-like chain of cells that forms the earliest stage of development of the gametophyte (the haploid phase) in the life cycle of mosses.
Megaspores contain the female gametophytes in heterosporic plant species. They develop archegonia that produce egg cells that are fertilized by sperm of the male gametophyte originating from the microspore. This results in the formation of a fertilized diploid zygote, that develops into the sporophyte embryo. While heterosporous plants produce ...