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Bryophytes are an informal group consisting of three divisions of non-vascular land plants embryophytes: They reproduce via spores. Bryophytes are usually considered to be a paraphyletic group and not a monophyletic group, although some studies have produced contrary results. Regardless of their status, the name is convenient and remains in use as an informal collective term. Bryophytes bryolhyta in a wide variety of habitats.
They can be found growing in a range of temperatures cold arctics and in hot desertselevations sea-level to alpineand bryyophyta dry deserts to wet rainforests. Bryophytes can grow where vascularized plants cannot because they do not depend on roots for an uptake of nutrients from soil.
Bryophytes can survive on rocks and bare soil. Like all land plants embryophytes fili, bryophytes have life cycles with alternation of generations. In each cycle, a haploid gametophyteeach of whose cells contains a fixed number of unpaired chromosomesalternates with a diploid sporophytewhose cell contain two sets of paired chromosomes.
Gametophytes produce haploid sperm and eggs which fuse to form diploid zygotes that grow into sporophytes. bryophytz
Sporophytes produce haploid spores by meiosisthat grow into gametophytes. Bryophytes are gametophyte dominant, meaning that the more prominent, longer-lived plant is the haploid gametophyte.
In bryophytes, the sporophytes are always unbranched and produce a single sporangium spore producing capsule. Liverworts, mosses and hornworts spend most of their lives as gametophytes. Gametangia gamete-producing organsarchegonia and antheridiaare produced on the gametophytes, sometimes at the tips of shoots, in the axils of leaves or hidden under thalli.
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Some bryophytes, such as the liverwort Marchantiacreate elaborate structures to bear the gametangia that are bryopyhta gametangiophores. Sperm are flagellated and must swim from the antheridia that produce them to archegonia which may be on a different plant.
Arthropods can assist in transfer of sperm. Fertilized eggs become zygotes, which develop into sporophyte embryos inside the archegonia. Mature sporophytes remain attached to the gametophyte. They consist of a stalk called a seta and a single sporangium or capsule.
Inside the sporangium, haploid spores are produced by meiosis. These are dispersed, most commonly by wind, and if they land in a suitable environment can develop into a new gametophyte. Thus bryophytes disperse by a combination of swimming sperm and spores, in a manner similar to lycophytesferns and other cryptogams.
The arrangement of antheridia and archegonia on an individual bryophyte plant is usually constant within a species, although in some species it may depend on environmental conditions. The main division is between species in which the antheridia and archegonia occur on the same plant and those in which they occur on different plants. The term monoicous may bruophyta used where antheridia and archegonia occur on the same gametophyte and the term dioicous where they occur on different gametophytes.
In seed plants” monoecious ” is used where flowers with anthers microsporangia and flowers with ovules megasporangia occur on the same sporophyte and ” dioecious ” where they occur on different sporophytes. These terms occasionally may be used instead of “monoicous” and “dioicous” to describe bryophyte bdyophyta.
The use of the “oicy” terminology is said to have the advantage of emphasizing the difference between the gametophyte sexuality of bryophytes and the sporophyte sexuality of seed plants. Monoicous plants are necessarily bisexual or hermaphroditicmeaning that the same plant has both sexes. They may be borne on different shoots autoicous or autoeciouson the same shoot but not together in a common structure paroicous or paroeciousor together in a common “inflorescence” synoicous or synoecious.
Traditionally, all living land plants without vascular tissues were classified in a single taxonomic group, often a division or phylum. More recently, phylogenetic research has questioned whether the bryophytes form a monophyletic group and broyphyta whether they should form a single taxon.
Although a study supported the traditional view that the bryophytes form a monophyletic group,  by a broad consensus had emerged among systematists that bryophytes as a whole are not a natural group i.
The three bryophyte clades which may be treated as divisions are the Marchantiophyta liverwortsBryophyta mosses and Anthocerotophyta hornworts. In this analysis, hornworts are sister to vascular plants and liverworts are sister to all other land plants, including the hornworts and mosses.
In particular those based on gene sequences suggest the bryophytes are paraphyletic, whereas those based on the amino acid translations of the same genes suggest they are monophyletic.
A study concluded that composition biases were responsible for these differences and that the bryophytes are monophyletic. When extinct plants are taken into account, the picture is slightly altered.
Some extinct land plants, such as the horneophytesare not bryophytes, but also are not vascular plants because, like bryophytes, they do not have true vascular tissue. A different distinction is needed. In bryophytes, the sporophyte is a simple unbranched structure with a single spore-forming organ sporangium.
In all other land plants, the polysporangiophytesthe sporophyte is branched and carries many sporangia. The term “bryophyte” thus refers to a grade of lineages defined primarily by what they lack. Compared to other living land plants, they lack vascular tissue containing lignin and branched sporophytes bearing multiple sporangia.
The prominence of the gametophyte in the life cycle is also a shared feature of the three bryophyte lineages extant vascular plants are all sporophyte dominant. An alternative phylogeny, based on amino acids rather than genes, shows bryophytes as a monophyletic group: If this phylogeny proves correct, then the complex sporophyte of living vascular plants might have evolved independently of the simpler unbranched sporophyte present in bryophytes.
Between – million years ago, land plants evolved from aquatic plants, specifically green algae. Molecular phylogenetic studies conclude that bryophytes are the earliest diverging lineages of the extant land plants. A number of physical features link bryophytes to both land plants and aquatic plants.
Distinct adaptations observed in bryophytes have allowed plants to colonize Earth’s terrestrial environments. To prevent desiccation of plant tissues in a terrestrial environment, a waxy cuticle covering the soft tissue of the plant provides protection.
The development bryophyts gametangia provided further protection specifically for gametes. Bryophytes also exhibit connections to their aquatic ancestry. They share various features with their green algae ancestors. Both green algae and bryophytes have chlorophyll a and b, and the chloroplast structures are similar. Bryophytes depend on water for reproduction and survival.
A thin layer of water is required on the surface of the plant to enable the movement of sperm between gametophytes and the fertilization of an egg. Summary of the morphological characteristics of the gametophytes of the three groups of bryophytes:. Summary of the morphological characteristics of the bryophtta of the three groups of bryophytes:.
Characteristics of bryophytes make them useful to the environment. Depending on the specific plant texture, bryophytes have been shown to help improve the water retention and air space within soil. The liverwort, Plagiochila, produces a chemical that is poisonous to mice.
Peat is a fuel that is produced from dried bryophytes, typically sphagnum. Bryophytes antibiotic properties and ability to retain water make them a useful packaging material for vegetables, flowers, and bulbs.
From Wikipedia, the free encyclopedia. This article is in a list format that may be better presented using prose. You can help by converting this article bryophytx prose, if appropriate. Editing help is available. Volume 1 Physiological Ecology.
British Mosses and Liverworts 3rd ed. Watson uses the “oecy” terms rather than the “oicy” terms. Plant Systematics and Evolution.
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The closest living relatives of early land plants”. Proceedings of the National Academy of Sciences. Generic-level structure and incongruent gene trees”. Molecular Phylogenetics and Evolution. American Journal of Botany. Windows into the early evolution of land plants”. Freeman and Company Publishers.
Cell wall Phragmoplast Plastid Plasmodesma Vacuole. Agronomy Floriculture Forestry Horticulture. Botanical terms Botanists by author abbreviation Botanical expedition. Cyanidiophyceae Porphyridiophyceae Compsopogonophyceae Stylonematophyceae Rhodellophyceae Bangiophyceae Florideophyceae. Glaucocystophyceae Glaucocystis Cyanophora Gloeochaete. Brjophyta Coleochaetophyceae Zygnematophyceae Mesotaeniaceae. See also the list of plant orders. Retrieved from ” https: Bryophytes Cryptogams Paraphyletic groups.
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