Non-vascular plants are plants without a vascular system consisting of xylem and phloem . Instead, they may possess simpler tissues that have specialized functions for the internal transport of water.
72-542: Mosses are small, non-vascular flowerless plants in 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
144-457: A megasporangium that produces megaspores or a microsporangium that produces microspores. In flowering plants, these sporangia occur within the carpel and anthers, respectively. Fungi commonly produce spores during sexual and asexual reproduction. Spores are usually haploid and grow into mature haploid individuals through mitotic division of cells ( Urediniospores and Teliospores among rusts are dikaryotic). Dikaryotic cells result from
216-519: 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 ,
288-403: A "spore" and a " gamete " is that a spore will germinate and develop into a sporeling , while a gamete needs to combine with another gamete to form a zygote before developing further. The main difference between spores and seeds as dispersal units is that spores are unicellular, the first cell of a gametophyte, while seeds contain within them a developing embryo (the multicellular sporophyte of
360-437: A center pole. This shows that four spores shared a common origin and were initially in contact with each other forming a tetrahedron. A wider aperture in the shape of a groove may be termed a colpus . The number of colpi distinguishes major groups of plants. Eudicots have tricolpate spores (i.e. spores with three colpi). Envelope-enclosed spore tetrads are taken as the earliest evidence of plant life on land, dating from
432-407: 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
504-924: 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
576-408: 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
648-535: 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
720-414: 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
792-485: A pivotal role. Spore In biology , a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants , algae , fungi and protozoa . They were thought to have appeared as early as the mid-late Ordovician period as an adaptation of early land plants. Bacterial spores are not part of
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#1732773134512864-595: A putrid odour, for dispersal of fungal spores is yet another strategy, most prominently used by the stinkhorns . In Common Smoothcap moss ( Atrichum undulatum ), the vibration of sporophyte has been shown to be an important mechanism for spore release. In the case of spore-shedding vascular plants such as ferns, wind distribution of very light spores provides great capacity for dispersal. Also, spores are less subject to animal predation than seeds because they contain almost no food reserve; however they are more subject to fungal and bacterial predation. Their chief advantage
936-437: 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
1008-423: A sexual cycle, but are resistant structures used for survival under unfavourable conditions. Myxozoan spores release amoeboid infectious germs ("amoebulae") into their hosts for parasitic infection, but also reproduce within the hosts through the pairing of two nuclei within the plasmodium, which develops from the amoebula. In plants, spores are usually haploid and unicellular and are produced by meiosis in
1080-411: 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
1152-434: 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
1224-441: 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
1296-544: 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
1368-440: 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
1440-502: 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,
1512-478: Is that spores were an adaptation of early land plant species, such as embryophytes , that allowed for plants to easily disperse while adapting to their non-aquatic environment. This is particularly supported by the observation of a thick spore wall in cryptospores . These spore walls would have protected potential offspring from novel weather elements. The second more recent hypothesis is that spores were an early predecessor of land plants and formed during errors in
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#17327731345121584-451: Is that, of all forms of progeny, spores require the least energy and materials to produce. In the spikemoss Selaginella lepidophylla , dispersal is achieved in part by an unusual type of diaspore , a tumbleweed . Spores have been found in microfossils dating back to the mid-late Ordovician period. Two hypothesized initial functions of spores relate to whether they appeared before or after land plants. The heavily studied hypothesis
1656-534: 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
1728-544: 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
1800-556: 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
1872-474: 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
1944-497: The ferns and fern allies that reproduce using spores. Non-vascular plants are often among the first species to move into new and inhospitable territories, along with prokaryotes and protists , and thus function as pioneer species . Mosses and leafy liverworts have structures called phyllids that resemble leaves , but only consist of single sheets of cells with no internal air spaces, no cuticle or stomata , and no xylem or phloem. Consequently, phyllids are unable to control
2016-408: 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
2088-491: The meiosis of algae , a hypothesized early ancestor of land plants. Whether spores arose before or after land plants, their contributions to topics in fields like paleontology and plant phylogenetics have been useful. The spores found in microfossils, also known as cryptospores, are well preserved due to the fixed material they are in as well as how abundant and widespread they were during their respective time periods. These microfossils are especially helpful when studying
2160-409: 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
2232-496: The sporangium of a diploid sporophyte . In some rare cases, diploid spore is also produced in some algae, or fungi. Under favourable conditions, the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte , which eventually goes on to produce gametes. Two gametes fuse to form a zygote , which develops into a new sporophyte. This cycle is known as alternation of generations . The spores of seed plants are produced internally, and
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2304-499: 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
2376-428: 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
2448-406: 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
2520-445: 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
2592-538: 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
2664-404: 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
2736-585: 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
2808-613: 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,
2880-418: 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
2952-467: 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
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3024-465: 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
3096-442: 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
3168-401: 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,
3240-569: The fluids of the ascus that lead to explosive discharge of the ascospores into the air. The forcible discharge of single spores termed ballistospores involves formation of a small drop of water ( Buller's drop ), which upon contact with the spore leads to its projectile release with an initial acceleration of more than 10,000 g . Other fungi rely on alternative mechanisms for spore release, such as external mechanical forces, exemplified by puffballs . Attracting insects, such as flies, to fruiting structures, by virtue of their having lively colours and
3312-607: The functioning of peatlands. This provides essential goods and services to humans such as global carbon sinks, water purification systems, fresh water reserves as well as biodiversity and peat resources. This is achieved through nutrient acquisition from dominant plants under nutrient-stressed conditions. Non-vascular plants can also play important roles in other biomes such as deserts, tundra and alpine regions. They have been shown to contribute to soil stabilization, nitrogen fixation, carbon assimilation etc. These are all crucial components in an ecosystem in which non-vascular plants play
3384-735: The fusion of two haploid gamete cells. Among sporogenic dikaryotic cells, karyogamy (the fusion of the two haploid nuclei) occurs to produce a diploid cell. Diploid cells undergo meiosis to produce haploid spores. Spores can be classified in several ways such as by their spore producing structure, function, origin during life cycle, and mobility. Below is a table listing the mode of classification, name, identifying characteristic, examples, and images of different spore species. Under high magnification , spores often have complex patterns or ornamentation on their exterior surfaces. A specialized terminology has been developed to describe features of such patterns. Some markings represent apertures, places where
3456-483: The gametophyte generation is dominant. In these plants, the sporophytes grow from and are dependent on gametophytes for supply of water and mineral nutrients and photosynthate, the products of photosynthesis . Non-vascular plants play crucial roles in their environments. They often dominate certain biomes such as mires, bogs and lichen tundra where these plants perform primary ecosystem functions. Additionally, in bogs mosses host microbial communities which help support
3528-633: 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
3600-610: 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
3672-661: 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
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#17327731345123744-474: The local climate, mosses in green roofs require no irrigation once established and are low maintenance. Mosses are also used on green walls . Non-vascular plant Non-vascular plants include two distantly related groups: These groups are sometimes called "lower plants", referring to their status as the earliest plant groups to evolve, but the usage is imprecise since both groups are polyphyletic and may be used to include vascular cryptogams , such as
3816-408: The megaspores (formed within the ovules) and the microspores are involved in the formation of more complex structures that form the dispersal units, the seeds and pollen grains. The term spore derives from the ancient Greek word σπορά spora , meaning " seed , sowing", related to σπόρος sporos , "sowing", and σπείρειν speirein , "to sow". In common parlance, the difference between
3888-533: The mid-Ordovician (early Llanvirn, ~ 470 million years ago ), a period from which no macrofossils have yet been recovered. Individual trilete spores resembling those of modern cryptogamic plants first appeared in the fossil record at the end of the Ordovician period. In fungi, both asexual and sexual spores or sporangiospores of many fungal species are actively dispersed by forcible ejection from their reproductive structures. This ejection ensures exit of
3960-443: The next generation), produced by the fusion of the male gamete of the pollen tube with the female gamete formed by the megagametophyte within the ovule. Spores germinate to give rise to haploid gametophytes, while seeds germinate to give rise to diploid sporophytes. Vascular plant spores are always haploid . Vascular plants are either homosporous (or isosporous) or heterosporous . Plants that are homosporous produce spores of
4032-424: 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
4104-479: 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
4176-527: 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
4248-464: 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
4320-427: The rate of water loss from their tissues and are said to be poikilohydric . 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 . 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,
4392-417: 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
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#17327731345124464-569: 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 ,
4536-567: 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
4608-442: 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
4680-399: The same size and type. Heterosporous plants, such as seed plants , spikemosses , quillworts , and ferns of the order Salviniales produce spores of two different sizes: the larger spore (megaspore) in effect functioning as a "female" spore and the smaller (microspore) functioning as a "male". Such plants typically give rise to the two kind of spores from within separate sporangia, either
4752-472: 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 ,
4824-407: The spores from the reproductive structures as well as travelling through the air over long distances. Many fungi thereby possess specialized mechanical and physiological mechanisms as well as spore-surface structures, such as hydrophobins , for spore ejection. These mechanisms include, for example, forcible discharge of ascospores enabled by the structure of the ascus and accumulation of osmolytes in
4896-429: 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
4968-418: The tough outer coat of the spore can be penetrated when germination occurs. Spores can be categorized based on the position and number of these markings and apertures. Alete spores show no lines. In monolete spores , there is a single narrow line (laesura) on the spore. Indicating the prior contact of two spores that eventually separated. In trilete spores , each spore shows three narrow lines radiating from
5040-496: 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
5112-458: 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
5184-511: 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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