Bryophyta

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Bryophyta (bryophytes) A division of plants which for some authors includes the mosses (Musci) and liverworts (Hepaticae), but is now often taken to include only the mosses; liverworts having been assigned divisional status as Hepatophyta. Bryophytes differ from algae in that the multicellular gametangium is surrounded by a protective jacket of sterile cells; gametangia of algae are usually unicellular and never have a protective jacket of sterile cells. Although bryophytes lack differentiated water-conducting vessels, and rely largely or entirely on water absorbed from rain falling on the plants, or from a moist atmosphere, some larger species may have simple water-conducting cells. They lack true roots, but possess root-like rhizoids which anchor them to a substrate and which can absorb water and minerals. The plants all show a heteromorphic alternation of generations, with a green vegetative gametophyte (the familiar moss or liverwort plant) and a sporophyte which typically takes the form of a (usually stalked) capsule and which is partially or wholly parasitic on the gametophyte. Most bryophytes are land plants and are found worldwide in a range of habitats. They are known from Devonian rocks, but there is no evidence to link them with either the green algae or the more advanced pteridophytes.

Bryophyta

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Bryophyta (bryophytes) A division of plants which for most authors includes the mosses and liverworts. Although bryophytes lack differentiated water-conducting vessels and rely largely or entirely on water absorbed from rain falling on the plants or from a moist atmosphere, they may have simple water-conducting cells in some larger species. They lack true roots, but possess root-like rhizoids which anchor them to a substrate and which can absorb water and minerals. The plants all show an alternation of generations, with a green-vegetative gametophyte (the familiar moss or liverwort plant) and a sporophyte which typically takes the form of a (usually stalked) capsule and which is partially or wholly parasitic on the gametophyte. Most bryophytes are land plants and are found world-wide in a range of habitats. They are known from Devonian rocks, the earliest fossil bryophyte being a compression of a thalloid liverwort, Pallavicinites devonicus. The earliest fossil moss is Musites polytrichaceus from the Upper Carboniferous of France. There is no evidence to link bryophytes with either the green algae (Chlorophyceae) or the more advanced pteridophytes.

Bryophyta

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Bryophyta A phylum of simple plants possessing no vascular tissue and rudimentary rootlike organs (rhizoids). They grow in a variety of damp habitats, from fresh water to rock surfaces. Some use other plants for support. Mosses show a marked alternation of generations between gamete-bearing forms (gametophytes) and spore-bearing forms (sporophytes): they possess erect or prostrate leafy stems (the gametophyte generation, which is haploid); these give rise to leafless stalks bearing capsules (the sporophyte generation, which is diploid), the latter being dependent on the former for water and nutrients. Spores formed in the capsules are released and grow to produce new plants.

Formerly, this phylum also included the liverworts and hornworts, now regarded as separate phyla (see Hepatophyta; Anthocerophyta) and the mosses were classified as a class (Musci) of the Bryophyta. The term `bryophytes' is still used informally to refer to members of all three phyla.