58-446: See text. Polytrichaceae is a common family of mosses . Members of this family tend to be larger than other mosses, with the larger species occurring in particularly moist habitats. The leaves have specialized sheaths at the base and a midrib that bears photosynthetic lamellae on the upper surface. These mosses are capable of sustaining high rates of photosynthesis in the presence of ample light and moisture. Unlike all other mosses,
116-425: A polymeric carbohydrate compound isomeric with common starch . It also yields a peculiar modification of chlorophyll (called thallochlor ), fumaric acid , lichenostearic acid , and cetraric acid (which gives it the bitter taste). It also contains lichesterinic acid and protolichesterinic acids . It grows abundantly in the mountainous regions of northern countries, and it is specially characteristic of
174-520: A stem that may be branched or unbranched and has only a limited role in conducting water and nutrients. Although some species have conducting tissues, these are generally poorly developed and structurally different from similar tissue found in vascular plants . Mosses do not have seeds and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing spores . They are typically 0.2–10 cm (0.1–3.9 in) tall, though some species are much larger. Dawsonia ,
232-528: A few traditional dishes. In earlier times, it was much more widely used in breads, porridges, soups, etc. It forms a nutritious and easily digested amylaceous food, being used in place of starch in some preparations of hot chocolate . Cetraric acid or cetrarin , a white micro-crystalline powder with a bitter taste, is readily soluble in alcohol , and slightly soluble in water and ether . It has been recommended for medicinal use by alternative medicine sites, in doses of 2 to 4 grains (0.1 to 0.25 grams), as
290-407: A few years of exposure to wind and rain. Materials which are porous and moisture retentive, such as brick , wood , and certain coarse concrete mixtures, are hospitable to moss. Surfaces can also be prepared with acidic substances, including buttermilk , yogurt , urine , and gently puréed mixtures of moss samples, water and ericaceous compost . In the cool, humid, cloudy Pacific Northwest , moss
348-916: A garden weed in Vancouver and Seattle areas; Bryum argenteum , the cosmopolitan sidewalk moss, and Ceratodon purpureus , red roof moss, another cosmopolitan species. A few species are wholly aquatic, such as Fontinalis antipyretica , common water moss; and others such as Sphagnum inhabit bogs, marshes and very slow-moving waterways. Such aquatic or semi-aquatic mosses can greatly exceed the normal range of lengths seen in terrestrial mosses. Individual plants 20–30 cm (8–12 in) or more long are common in Sphagnum species for example. But even aquatic species of moss and other bryophytes needs their mature capsules to be exposed to air by seta elongation or seasonal lowering of water level to be able to reproduce. Wherever they occur, mosses require liquid water for at least part of
406-408: A haploid spore that germinates to produce a protonema ( pl. protonemata), which is either a mass of thread-like filaments or thalloid (flat and thallus-like). Massed moss protonemata typically look like a thin green felt, and may grow on damp soil, tree bark, rocks, concrete, or almost any other reasonably stable surface. This is a transitory stage in the life of a moss, but from the protonema grows
464-524: A member of the Polytrichidae is probably Dawsonia superba , a native to New Zealand and other parts of Australasia . The fossil record of moss is sparse, due to their soft-walled and fragile nature. Unambiguous moss fossils have been recovered from as early as the Permian of Antarctica and Russia, and a case has been made for Carboniferous mosses. It has further been claimed that tube-like fossils from
522-433: A pale chestnut color , but varies considerably, being sometimes almost entirely grayish-white; and grows to a height of from 7.6 to 10.2 centimetres (3 to 4 inches), the branches being channelled or rolled into tubes, which end in flattened lobes with fringed edges. In commerce it is a light-gray harsh cartilaginous body, almost colorless, and tastes slightly bitter . It contains about 70% of lichenin or lichen-starch,
580-414: A partner that contains the same, or similar, genetic information. By contrast, mosses and other bryophytes have only a single set of chromosomes and so are haploid (i.e. each chromosome exists in a unique copy within the cell). There is a period in the moss life cycle when they do have a double set of paired chromosomes, but this happens only during the sporophyte stage. The moss life-cycle starts with
638-438: A scent-mediated relationship analogous to the plant-pollinator relationship found in many seed plants. The stinkmoss species Splachnum sphaericum develops insect pollination further by attracting flies to its sporangia with a strong smell of carrion, and providing a strong visual cue in the form of red-coloured swollen collars beneath each spore capsule. Flies attracted to the moss carry its spores to fresh herbivore dung, which
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#1732852534851696-412: A similar purpose. Mosses can be either dioicous (compare dioecious in seed plants) or monoicous (compare monoecious ). In dioicous mosses, male and female sex organs are borne on different gametophyte plants. In monoicous (also called autoicous) mosses, both are borne on the same plant. In the presence of water, sperm from the antheridia swim to the archegonia and fertilisation occurs, leading to
754-455: A stopper mechanism, which consists of the apical section of the columella , that seals the mouth of the capsule shut prior to dehiscence . Takakiopsida Sphagnopsida Andreaeopsida Andreaeobryopsida Oedipodiopsida Tetraphidopsida Polytrichaceae Bryopsida This moss -related article is a stub . You can help Misplaced Pages by expanding it . Moss Mosses are small, non-vascular flowerless plants in
812-435: Is deliberately encouraged to grow under aesthetic principles exemplified by Japanese gardening . In old temple gardens, moss can carpet a forest scene. Moss is thought to add a sense of calm, age, and stillness to a garden scene. Moss is also used in bonsai to cover the soil and enhance the impression of age. Rules of cultivation are not widely established. Moss collections are quite often begun using samples transplanted from
870-448: Is disrupted by fungal chitin . Galotto et al. , 2020 applied chitooctaose and found that tips detected and responded to this chitin derivative by changing gene expression . They concluded that this defense response was probably conserved from the most recent common ancestor of bryophytes and tracheophytes . Orr et al. , 2020 found that the microtubules of growing tip cells were structurally similar to F-actin and served
928-545: Is famous for its moss garden. The moss garden was created by removing shrubby underbrush and herbaceous groundcovers, thinning trees, and allowing mosses to fill in naturally. Mosses are sometimes used in green roofs . Advantages of mosses over higher plants in green roofs include reduced weight loads, increased water absorption, no fertilizer requirements, and high drought tolerance. Since mosses do not have true roots, they require less planting medium than higher plants with extensive root systems. With proper species selection for
986-446: Is positively associated with the presence of dwarf males in several phyllodioicous species. Dwarf males occur in several unrelated lineages and may be more common than previously thought. For example, it is estimated that between one quarter and half of all dioicous pleurocarps have dwarf males. The moss Physcomitrium patens has been used as a model organism to study how plants repair damage to their DNA, especially
1044-499: Is sometimes allowed to grow naturally as a moss lawn , one that needs little or no mowing, fertilizing or watering. In this case, grass is considered to be the weed. Landscapers in the Seattle area sometimes collect boulders and downed logs growing mosses for installation in gardens and landscapes. Woodland gardens in many parts of the world can include a carpet of natural mosses. The Bloedel Reserve on Bainbridge Island, Washington State,
1102-534: Is the dominant phase of the life cycle . This contrasts with the pattern in all vascular plants ( seed plants and pteridophytes ), where the diploid sporophyte generation is dominant. Mosses reproduce using spores , not seeds , and have no flowers. 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. In
1160-545: Is the favoured habitat of the species of this genus. In many mosses, e.g., Ulota phyllantha , green vegetative structures called gemmae are produced on leaves or branches, which can break off and form new plants without the need to go through the cycle of fertilization. This is a means of asexual reproduction , and the genetically identical units can lead to the formation of clonal populations. Moss dwarf males (also known as nannandry or phyllodioicy ) originate from wind-dispersed male spores that settle and germinate on
1218-547: The Silurian are the macerated remains of moss calyptræ . Mosses also appear to evolve 2–3 times slower than ferns, gymnosperms and angiosperms . Recent research shows that ancient moss could explain why the Ordovician ice ages occurred. When the ancestors of today's moss started to spread on land 470 million years ago, they absorbed CO 2 from the atmosphere and extracted minerals by secreting organic acids that dissolved
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#17328525348511276-466: The Southern Hemisphere . Some naturalists feel that mosses grow on the damper side of trees and rocks. In some cases, such as sunny climates in temperate northern latitudes, this will be the shaded north side of the tree or rock. On steep slopes, it may be the uphill side. For mosses that grow on tree branches, this is generally the upper side of the branch on horizontally growing sections or near
1334-408: The gametophore ("gamete-bearer") that is structurally differentiated into stems and leaves. A single mat of protonemata may develop several gametophore shoots, resulting in a clump of moss. From the tips of the gametophore stems or branches develop the sex organs of the mosses. The female organs are known as archegonia ( sing. archegonium ) and are protected by a group of modified leaves known as
1392-448: The hydroid -based vascular system of these mosses is continuous from stem to leaf and can extract water from the soil through transpiration . Species in this group are dioicous , though some are monoicous . In most species, the sporophytes are relatively large, the setae are rigid, and the calyptrae are hairy. Most species have nematodontous peristomes with 32–64 teeth in their sporangium ; some early-diverging genera instead have
1450-456: The lichenicolous fungus species Lichenopeltella cetrariicola , which is known from Europe and Iceland . All parts of the lichen are edible. It may be dry in winter but can be soaked. Boiling reduces the bitterness. It can be added as a thickener to milk or grains or dried and stored. It is not in great demand, and even in Iceland it is only occasionally used to make folk medicines and in
1508-410: The polysporangiophytes , which include all vascular plants. The spore-producing sporophytes (i.e. the diploid multicellular generation) are short-lived and usually capable of photosynthesis, but are dependent on the gametophyte for water supply and most or all of its nutrients. Also, in the majority of mosses, the spore-bearing capsule enlarges and matures after its stalk elongates, while in liverworts
1566-502: The atmosphere. Small organisms feeding on the nutrients created large areas without oxygen, which caused a mass extinction of marine species, while the levels of CO 2 dropped all over the world, allowing the formation of ice caps on the poles. Moss gametophytes are autotrophic and require sunlight to perform photosynthesis . Shade tolerance varies by species, just as it does with higher plants. In most areas, mosses grow chiefly in moist, shaded areas, such as wooded areas and at
1624-430: The capsule enlarges and matures before its stalk elongates. Other differences are not universal for all mosses and all liverworts, but the presence of a clearly differentiated stem with simple-shaped, non-vascular leaves that are not arranged in three ranks, all point to the plant being a moss. Vascular plants have two sets of chromosomes in their vegetative cells and are said to be diploid , i.e. each chromosome has
1682-407: The capsule is mature. Within the capsule, spore-producing cells undergo meiosis to form haploid spores, upon which the cycle can start again. The mouth of the capsule is usually ringed by a set of teeth called peristome. This may be absent in some mosses. Most mosses rely on the wind to disperse the spores. In the genus Sphagnum the spores are projected about 10–20 cm (4–8 in) off
1740-449: The classes Bryopsida, Marchantiopsida, and Anthocerotopsida, respectively. The mosses and liverworts are now considered to belong to a clade called Setaphyta . The mosses, (Bryophyta sensu stricto), are divided into eight classes: vascular plants hornworts liverworts Takakiopsida Sphagnopsida Andreaeopsida Andreaeobryopsida Oedipodiopsida Polytrichopsida Tetraphidopsida Bryopsida Six of
1798-539: The crotch. In cool, humid, cloudy climates, all sides of tree trunks and rocks may be equally moist enough for moss growth. Each species of moss requires certain amounts of moisture and sunlight and thus will grow on certain sections of the same tree or rock. Some mosses grow underwater, or completely waterlogged. Many prefer well-drained locations. There are mosses that preferentially grow on rocks and tree trunks of various chemistries. In boreal forests , some species of moss play an important role in providing nitrogen for
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1856-405: The ecosystem due to their relationship with nitrogen-fixing cyanobacteria . Cyanobacteria colonize moss and receive shelter in return for providing fixed nitrogen. Moss releases the fixed nitrogen, along with other nutrients, into the soil "upon disturbances like drying-rewetting and fire events", making it available throughout the ecosystem. Moss is often considered a weed in grass lawns, but
1914-585: The edges of streams, but they can grow anywhere in cool, humid, cloudy climates, and some species are adapted to sunny, seasonally dry areas like alpine rocks or stabilized sand dunes. Choice of substrate varies by species as well. Moss species can be classed as growing on: rocks, exposed mineral soil, disturbed soils, acid soil, calcareous soil, cliff seeps and waterfall spray areas, streamsides, shaded humusy soil, downed logs, burnt stumps, tree trunk bases, upper tree trunks, and tree branches or in bogs . Moss species growing on or under trees are often specific about
1972-613: The eight classes contain only one or two genera each. Polytrichopsida includes 23 genera, and Bryopsida includes the majority of moss diversity with over 95% of moss species belonging to this class. The Sphagnopsida, the peat-mosses, comprise the two living genera Ambuchanania and Sphagnum , as well as fossil taxa. Sphagnum is a diverse, widespread, and economically important one. These large mosses form extensive acidic bogs in peat swamps. The leaves of Sphagnum have large dead cells alternating with living photosynthetic cells. The dead cells help to store water. Aside from this character,
2030-420: The exception of the ancient group Takakiopsida , no known mosses form mycorrhiza , but bryophilous fungi is widespread in moss and other bryophytes, where they live as saprotrophs, parasites, pathogens and mutualists, some of them endophytes . Mosses differ from vascular plants in lacking water-bearing xylem tracheids or vessels . As in liverworts and hornworts , the haploid gametophyte generation
2088-472: The female shoot where their growth is restricted to a few millimeters. In some species, dwarfness is genetically determined, in that all male spores become dwarf. More often, it is environmentally determined in that male spores that land on a female become dwarf, while those that land elsewhere develop into large, female-sized males. In the latter case, dwarf males that are transplanted from females to another substrate develop into large shoots, suggesting that
2146-468: The females emit a substance which inhibits the growth of germinating males and possibly also quickens their onset of sexual maturation. The nature of such a substance is unknown, but the phytohormone auxin may be involved Having the males growing as dwarfs on the female is expected to increase the fertilization efficiency by minimizing the distance between male and female reproductive organs. Accordingly, it has been observed that fertilization frequency
2204-443: The fertilization distance. After fertilisation, the immature sporophyte pushes its way out of the archegonial venter. It takes several months for the sporophyte to mature. The sporophyte body comprises a long stalk, called a seta, and a capsule capped by a cap called the operculum . The capsule and operculum are in turn sheathed by a haploid calyptra which is the remains of the archegonial venter. The calyptra usually falls off when
2262-401: The fins on a heat sink. These carry out photosynthesis and may help to conserve moisture by partially enclosing the gas exchange surfaces. The Polytrichopsida differ from other mosses in other details of their development and anatomy too, and can also become larger than most other mosses, with e.g., Polytrichum commune forming cushions up to 40 cm (16 in) high. The tallest land moss,
2320-636: The genus Sphagnum ), although they are also used for decorative purposes, such as in gardens and in the florist trade. Traditional uses of mosses included as insulation and for the ability to absorb liquids up to 20 times their weight. Moss is a keystone genus and benefits habitat restoration and reforestation . Botanically, mosses are non-vascular plants in the land plant division Bryophyta. They are usually small (a few centimeters tall) herbaceous (non-woody) plants that absorb water and nutrients mainly through their leaves and harvest carbon dioxide and sunlight to create food by photosynthesis . With
2378-614: The ground by compressed air contained in the capsules; the spores are accelerated to about 36,000 times the earth's gravitational acceleration g . It has recently been found that microarthropods, such as springtails and mites , can effect moss fertilization and that this process is mediated by moss-emitted scents. Male and female fire moss , for example emit different and complex volatile organic scents. Female plants emit more compounds than male plants. Springtails were found to choose female plants preferentially, and one study found that springtails enhance moss fertilization, suggesting
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2436-524: The lava slopes and plains of the west and north of Iceland . It is found on the mountains of north Wales , northern England , Scotland and south-west Ireland . In North America its range extends through Arctic regions, from Alaska to Newfoundland , and south in the Rocky Mountains to Colorado, and to the Appalachian Mountains of New England. Cetraria islandica is a known host to
2494-664: The leaf can be smooth or it may have teeth. There may be a distinct type of cell defining the edge of the leaf, distinct in shape and/or colour from the other leaf cells. Moss has threadlike rhizoids that anchor them to their substrate, comparable to root hairs rather than the more substantial root structures of spermatophytes . Mosses do not absorb water or nutrients from their substrate through their rhizoids. They can be distinguished from liverworts ( Marchantiophyta or Hepaticae) by their multi-cellular rhizoids. Spore-bearing capsules or sporangia of mosses are borne singly on long, unbranched stems, thereby distinguishing them from
2552-406: The local climate, mosses in green roofs require no irrigation once established and are low maintenance. Mosses are also used on green walls . Iceland moss Cetraria islandica , also known as true Iceland lichen or Iceland moss , is an Arctic-alpine lichen whose erect or upright, leaflike habit gives it the appearance of a moss , where its name likely comes from. It is often of
2610-426: The pattern in all vascular plants ( seed plants and pteridophytes ), where the diploid sporophyte generation is dominant. Lichens may superficially resemble mosses, and sometimes have common names that include the word "moss" (e.g., " reindeer moss " or " Iceland moss "), but they are fungal symbioses and not related to mosses. The main commercial significance of mosses is as the main constituent of peat (mostly
2668-480: The perichaetum (plural, perichaeta). The archegonia are small flask-shaped clumps of cells with an open neck (venter) down which the male sperm swim. The male organs are known as antheridia ( sing. antheridium ) and are enclosed by modified leaves called the perigonium ( pl. perigonia). The surrounding leaves in some mosses form a splash cup, allowing the sperm contained in the cup to be splashed to neighboring stalks by falling water droplets. Gametophore tip growth
2726-538: The principal sensor of DNA double-strand breaks) showed that these genes are necessary for repair of DNA damage as well as for normal growth and development. More recently, mosses have been grouped with the liverworts and hornworts in the division Bryophyta ( bryophytes , or Bryophyta sensu lato ). The bryophyte division itself contains three (former) divisions: Bryophyta (mosses), Marchantiophyta (liverworts) and Anthocerotophyta (hornworts); it has been proposed that these latter divisions are de-ranked to
2784-464: The production of a diploid sporophyte. The sperm of mosses is biflagellate, i.e. they have two flagellae that aid in propulsion. Since the sperm must swim to the archegonium, fertilisation cannot occur without water. Some species (for example Mnium hornum or several species of Polytrichum ) keep their antheridia in so called 'splash cups', bowl-like structures on the shoot tips that propel the sperm several decimeters when water droplets hit it, increasing
2842-418: The remaining classes, stomata have been lost more than 60 times. Their leaves are simple, usually only a single layer of cells with no internal air spaces, often with thicker midribs (nerves). The nerve can run beyond the edge of the leaf tip, termed excurrent. The tip of the leaf blade can be extended as a hair point, made of colourless cells. These appear white against the dark green of the leaves. The edge of
2900-557: The repair mechanism functions in plants. For example, a study of P. patens mutants defective in Rp RAD51, a gene that encodes a protein at the core of the recombinational repair reaction, indicated that homologous recombination is essential for repairing DNA double-strand breaks in this plant. Similarly, studies of mutants defective in Ppmre11 or Pprad50 (that encode key proteins of the MRN complex ,
2958-565: The repair mechanism known as homologous recombination . If the plant cannot repair DNA damage, e.g., double-strand breaks , in their somatic cells , the cells can lose normal functions or die. If this occurs during meiosis (part of sexual reproduction), they could become infertile. The genome of P. patens has been sequenced, which has allowed several genes involved in DNA repair to be identified. P. patens mutants that are defective in key steps of homologous recombination have been used to work out how
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#17328525348513016-442: The rocks they were growing on. These chemically altered rocks in turn reacted with the atmospheric CO 2 and formed new carbonate rocks in the ocean through the weathering of calcium and magnesium ions from silicate rocks. The weathered rocks also released significant amounts of phosphorus and iron which ended up in the oceans, where it caused massive algal blooms, resulting in organic carbon burial, extracting more carbon dioxide from
3074-473: The species of trees they grow on, such as preferring conifers over broadleaf trees , oaks over alders , or vice versa. While mosses often grow on trees as epiphytes , they are never parasitic on the tree. Mosses are also found in cracks between paving stones in damp city streets, and on roofs. Some species adapted to disturbed, sunny areas are well adapted to urban conditions and are commonly found in cities. Examples would be Rhytidiadelphus squarrosus ,
3132-433: The tallest moss in the world, can grow to 50 cm (20 in) in height. There are approximately 12,000 species. Mosses are commonly confused with liverworts, hornworts and lichens . Although often described as non-vascular plants , many mosses have advanced vascular systems. Like liverworts and hornworts, the haploid gametophyte generation of mosses is the dominant phase of the life cycle . This contrasts with
3190-486: The taxonomic division Bryophyta ( / b r aɪ ˈ ɒ f ə t ə / , / ˌ b r aɪ . ə ˈ f aɪ t ə / ) sensu stricto . Bryophyta ( sensu lato , Schimp . 1879 ) may also refer to the parent group bryophytes , which comprise liverworts , mosses, and hornworts . Mosses typically form dense green clumps or mats, often in damp or shady locations. The individual plants are usually composed of simple leaves that are generally only one cell thick, attached to
3248-496: The unique branching, thallose (flat and expanded) protonema, and explosively rupturing sporangium place it apart from other mosses. Andreaeopsida and Andreaeobryopsida are distinguished by the biseriate (two rows of cells) rhizoids, multiseriate (many rows of cells) protonema, and sporangium that splits along longitudinal lines. Most mosses have capsules that open at the top. Polytrichopsida have leaves with sets of parallel lamellae, flaps of chloroplast-containing cells that look like
3306-458: The wild in a water-retaining bag. Some species of moss can be extremely difficult to maintain away from their natural sites with their unique requirements of combinations of light, humidity, substrate chemistry, shelter from wind, etc. Growing moss from spores is even less controlled. Moss spores fall in a constant rain on exposed surfaces; those surfaces which are hospitable to a certain species of moss will typically be colonised by that moss within
3364-504: The year to complete fertilisation. Many mosses can survive desiccation , sometimes for months, returning to life within a few hours of rehydration. It is generally believed that in the Northern Hemisphere , the north side of trees and rocks will generally have more luxuriant moss growth on average than other sides. The reason is assumed to be because sunshine on the south side causes a dry environment. The reverse would be true in
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