Editing Moss

{{Short description|Division of non-vascular land plants}}
{{About|the division of plants||Moss (disambiguation)|and|Mosses (disambiguation)}}
{{Use dmy dates|date=July 2022}}
{{Automatic taxobox
| name = Moss
| fossil_range = [[Carboniferous]]<ref name="Hubers2012">{{cite journal |last1=Hubers|first1=M. |last2=Kerp|first2=H. |title=Oldest known mosses discovered in Mississippian (late Visean) strata of Germany |doi=10.1130/G33122.1 |journal=[[Geology (journal)|Geology]] |volume=40 |issue=8 |pages=755–58 |year=2012 |bibcode=2012Geo....40..755H}}</ref>–[[Holocene|present]] (Possible Cambrian records)<ref>{{cite journal |last1=Yang |first1=Rui-Dong |last2=Mao |first2=Jia-Ren |last3=Zhang |first3=Wei-Hua |last4=Jiang |first4=Li-Jun |last5=Gao |first5=Hui |title=Bryophyte-like Fossil (Parafunaria sinensis) from Early-Middle Cambrian Kaili Formation in Guizhou Province, China |journal=Acta Botanica Sinica |date=2004 |volume=46 |issue=2 |pages=180-185 |url=https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=48272290b152f4b9a902dded950a9995e006d163}}</ref>{{fossilrange|340|0|earliest=520}}
| image = Tionesta-ac-moss2.jpg
| image_caption = Clumps of moss on the ground and base of trees in the [[Allegheny National Forest]], Pennsylvania, United States
| display_parents = 2
| taxon = Bryophyta
| authority = [[Schimp.]] [[sensu stricto]]
| subdivision_ranks = Classes
| subdivision_ref = <ref name="Goffinet & Buck 2004"/>
| subdivision =
* [[Takakiopsida]]
* [[Sphagnopsida]]
* [[Andreaeopsida]]
* [[Andreaeobryopsida]]
* [[Oedipodiopsida]]
* [[Polytrichopsida]]
* [[Tetraphidopsida]]
* [[Bryopsida]]
| synonyms = *Musci L.
* Muscineae Bisch.
}}

'''Mosses''' are small, [[non-vascular plant|non-vascular]] [[flower]]less [[plant]]s in the taxonomic [[phylum|division]] '''Bryophyta''' ({{IPAc-en|b|r|aɪ|ˈ|ɒ|f|ə|t|ə}},<ref>{{cite Merriam-Webster|Bryophyta}}</ref> {{IPAc-en|ˌ|b|r|aɪ|.|ə|ˈ|f|aɪ|t|ə}}) ''[[sensu stricto]]''. Bryophyta (''[[sensu lato]]'', [[Wilhelm Philippe Schimper|Schimp]]. 1879<ref name=Schimp>{{cite book |title=Handbuch der Palaeontologie |editor-last=Zittel |editor-first=K.A. |last=Schimper |first=W. P. |year=1879 |section=Bryophyta |volume=2 |publisher=R. Oldenbourg}}</ref>) may also refer to the parent group [[bryophyte]]s, which comprise [[Marchantiophyta|liverworts]], mosses, and [[hornwort]]s.<ref name=Sousa2019>{{cite journal |title=Nuclear protein phylogenies support the monophyly of the three bryophyte groups (Bryophyta Schimp.) |last1=de Sousa |first1=Filipe |display-authors=etal |journal=[[New Phytologist]] |volume=222 |issue=1 |pages=565–75 |year=2019 |doi=10.1111/nph.15587
|pmid=30411803 |bibcode=2019NewPh.222..565D |hdl=1983/0b471d7e-ce54-4681-b791-1da305d9e53b |s2cid=53240320 |url=https://research-information.bris.ac.uk/en/publications/0b471d7e-ce54-4681-b791-1da305d9e53b |hdl-access=free}}</ref> Mosses typically form dense green clumps or mats, often in damp or shady locations. The individual plants are usually composed of simple [[leaf|leaves]] that are generally only one cell thick, attached to a [[plant stem|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]].<ref name=LigroneEtal>{{cite journal | last1 = Ligrone | first1 = R. | last2 = Duckett | first2 = J.G. | last3 = Renzaglia | first3 = K.S. | year = 2000 | title = Conducting tissues and phyletic relationships of bryophytes | journal = Philos Trans R Soc Lond B Biol Sci | volume = 355 | issue = 1398| pages = 795–813 | doi=10.1098/rstb.2000.0616| pmid = 10905610 | pmc = 1692789 }}</ref> Mosses do not have [[seed]]s and after fertilisation develop [[sporophyte]]s with unbranched stalks topped with single capsules containing [[sporangium|spores]]. They are typically {{Convert|0.2-10|cm|4 = 1|abbr = on}} tall, though some species are much larger. [[Dawsonia (plant)|''Dawsonia'']], the tallest moss in the world, can grow to {{Convert|50|cm|abbr = on}} in height. There are approximately 12,000 species.<ref name="Goffinet & Buck 2004">{{cite book| last=Goffinet | first = Bernard |author2=William R. Buck | year=2004 | chapter=Systematics of the Bryophyta (Mosses): From molecules to a revised classification | series=Molecular Systematics of Bryophytes | title=Monographs in Systematic Botany | volume=98 | pages=205–239 | publisher= Missouri Botanical Garden Press |isbn=978-1-930723-38-2 }}</ref>

Mosses are commonly confused with liverworts, hornworts and [[lichen]]s.<ref name=LNA>Lichens of North America, Irwin M. Brodo, Sylvia Duran Sharnoff, {{ISBN|978-0-300-08249-4}}, 2001</ref> Although often described as [[non-vascular plants]], many mosses have advanced vascular systems.<ref>{{Cite journal |last1=Bell |first1=N. E. |last2=Hyvönen |first2=J. |year=2010 |title=Phylogeny of the moss class Polytrichopsida (BRYOPHYTA): Generic-level structure and incongruent gene trees |journal=Molecular Phylogenetics and Evolution |volume=55 |issue=2 |pages=381–398 |doi=10.1016/j.ympev.2010.02.004 |name-list-style=amp|pmid=20152915|bibcode=2010MolPE..55..381B |url= https://zenodo.org/record/1065524 }}</ref><ref>{{cite journal |title=Advanced vascular function discovered in a widespread moss |last=Bodribb |first=T.J. |display-authors=etal |journal=Nature Plants |volume=6 |issue=3 |year=2020 |pages=273–279 |doi=10.1038/s41477-020-0602-x|pmid=32170283 |bibcode=2020NatPl...6..273B |s2cid=212641738 }}</ref> Like liverworts and hornworts, the [[haploid]] [[gametophyte]] generation of mosses is the dominant phase of the [[biological life cycle|life cycle]]. This contrasts with the pattern in all vascular plants ([[seed plants]] and [[pteridophytes]]), where the [[Ploidy#Diploid|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.<ref name=LNA />{{rp|3}}

The main commercial significance of mosses is as the main constituent of [[peat]] (mostly 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. Mosses are [[keystone species]] and benefit [[habitat restoration]] and [[reforestation]].<ref>{{Cite journal |last=Rochefort |first=Line |date=2000 |title=Sphagnum: A Keystone Genus in Habitat Restoration |url=https://www.jstor.org/stable/3244138 |journal=The Bryologist |volume=103 |issue=3 |pages=503–508 |doi=10.1639/0007-2745(2000)103[0503:SAKGIH]2.0.CO;2 |jstor=3244138 |s2cid=55699307 |issn=0007-2745}}</ref>

==Physical characteristics==

===Description===

[[File:Bryum capillare leaf cells.jpg|thumb|left|Chloroplasts (green discs) and accumulated starch granules in cells of ''[[Bryum|Bryum capillare]]'']]

Botanically, mosses are [[non-vascular plant]]s in the land plant division Bryophyta. They are usually small (a few centimeters tall) [[Herbaceous plant|herbaceous]] (non-woody) plants that absorb water and nutrients mainly through their leaves and harvest [[carbon dioxide]] and sunlight to create food by [[photosynthesis]].<ref name=mathews /><ref name=pojar /> With the exception of the ancient group [[Takakia|Takakiopsida]], no known mosses form [[mycorrhiza]],<ref>{{Cite journal|url=https://nph.onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2009.03137.x|title=Presence of three mycorrhizal genes in the common ancestor of land plants suggests a key role of mycorrhizas in the colonization of land by plants|first1=Bin|last1=Wang|first2=Li Huey|last2=Yeun|first3=Jia-Yu|last3=Xue|first4=Yang|last4=Liu|first5=Jean-Michel|last5=Ané|first6=Yin-Long|last6=Qiu|date=19 December 2010|journal=New Phytologist|volume=186|issue=2|pages=514–525|via=Wiley Online Library|doi=10.1111/j.1469-8137.2009.03137.x|pmid=20059702 |bibcode=2010NewPh.186..514W |hdl=2027.42/78704 |hdl-access=free}}</ref> but bryophilous fungi is widespread in moss and other bryophytes, where they live as saprotrophs, parasites, pathogens and mutualists, some of them [[endophyte]]s.<ref>{{Cite web|url=https://www.duo.uio.no/bitstream/handle/10852/11880/Heimdal.pdf?sequence=3|title=Using 454 sequencing for exploring diversity, host specificity and tissue specificity of the fungal genus Galerina associated with four boreal mosses}}</ref> Mosses differ from [[vascular plants]] in lacking water-bearing [[xylem]] [[tracheids]] or [[vessel elements|vessels]]. As in [[Marchantiophyta|liverworts]] and [[hornwort]]s, the [[haploid]] [[gametophyte]] generation is the dominant phase of the [[biological life cycle|life cycle]]. This contrasts with the pattern in all vascular plants ([[seed plants]] and [[pteridophytes]]), where the [[Haploid|diploid]] [[sporophyte]] generation is dominant. Mosses reproduce using [[spore]]s, not [[seed]]s, and have no flowers.

[[File:Moss leaf under microscope.jpg|thumb|upright=0.9|Moss leaf under microscope, showing [[Gemma (botany)|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 [[stoma]]ta or have pseudostomata that do not form pores. In the remaining classes, stomata have been lost more than 60 times.<ref>{{Cite journal|title=With Over 60 Independent Losses, Stomata Are Expendable in Mosses|first1=Karen S.|last1=Renzaglia|first2=William B.|last2=Browning|first3=Amelia|last3=Merced|date=28 May 2020|journal=Frontiers in Plant Science|volume=11|page=567 |doi=10.3389/fpls.2020.00567|doi-access=free |pmid=32547571 |pmc=7270291 |bibcode=2020FrPS...11..567R }}</ref> 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 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.<ref name="BBS - field guide2010">{{cite book |last1=Atherton |first1=Ian |last2=Bosanquet |first2=Sam |last3=Lawley |first3=Mark |title=Mosses and Liverworts of Britain and Ireland - a field guide |date=2010 |publisher=British Bryological Society |isbn=9780956131010 |pages=848}}</ref>

Moss has threadlike [[rhizoids]] that anchor them to their substrate, comparable to [[root hairs]] rather than the more substantial [[root]] structures of [[spermatophytes]].<ref name="Watson1981">{{cite book |last1=Watson |first1=E. Vernon |title=British Mosses and Liverworts |date=1981 |publisher=Cambridge University Press |isbn=052129472X |pages=519 |edition=3rd}}</ref> Mosses do not absorb water or nutrients from their substrate through their rhizoids.{{citation needed|date=April 2020}} They can be distinguished from [[Marchantiophyta|liverworts]] ([[Marchantiophyta]] or Hepaticae) by their multi-cellular rhizoids. Spore-bearing capsules or [[sporangium|sporangia]] of mosses are borne singly on long, unbranched stems, thereby distinguishing them from 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.<ref name=Budke-2018>{{cite journal |first1=Jessica M |last1=Budke |first2=Ernest C |last2=Bernard |first3=Dennis J |last3=Gray |first4=Sanna |last4=Huttunen |first5=Birgit |last5=Piechulla |first6=Robert N |last6=Trigiano |date=2018 |title=Introduction to the special issue on bryophytes |journal=Critical Reviews in Plant Sciences |volume=37 |issue=2–3 |pages=102–112 |doi=10.1080/07352689.2018.1482396 |bibcode=2018CRvPS..37..102B }}</ref> Also, in the majority of mosses, the spore-bearing capsule enlarges and matures after its stalk elongates, while in liverworts the capsule enlarges and matures before its stalk elongates.<ref name=pojar /> 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.{{citation needed|date=April 2023}}

===Life cycle===
<!-- This section is linked from "Alternation of generations"; be sure to change the link there if you change the title of this section. -->

Vascular [[plant]]s have two sets of [[chromosome]]s in their vegetative cells and are said to be [[diploid]], i.e. each chromosome has a partner that contains the same, or similar, genetic information. By contrast, mosses and other [[bryophyte]]s 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.

[[File:Lifecycle moss svg diagram.svg|thumb|300px|Life cycle of a typical moss (''[[Polytrichum commune]]'')]]

The moss life-cycle starts with 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 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 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.<ref name="vanderVelde2001" />

Gametophore tip growth is disrupted by fungal [[chitin]].<ref name="Delaux-Schornack-2021">{{cite journal | last1=Delaux | first1=Pierre-Marc | last2=Schornack | first2=Sebastian | title=Plant evolution driven by interactions with symbiotic and pathogenic microbes | journal=[[Science (journal)|Science]] | publisher=[[American Association for the Advancement of Science]] (AAAS) | volume=371 | issue=6531 | date=2021-02-19 | issn=0036-8075 | doi=10.1126/science.aba6605 | pages=1–10 | pmid=33602828 | s2cid=231955632| url=https://hal.archives-ouvertes.fr/hal-03327916/file/Delaux%20Schornack%20-%20HAL.pdf }}</ref><ref name="Bibeau-et-al-2021">{{cite journal | last1=Bibeau | first1=Jeffrey P. | last2=Galotto | first2=Giulia | last3=Wu | first3=Min | last4=Tüzel | first4=Erkan | last5=Vidali | first5=Luis | title=Quantitative cell biology of tip growth in moss | journal=[[Plant Molecular Biology]] | publisher=[[Springer Science+Business Media|Springer]] | volume=107 | issue=4–5 | date=2021-04-06 | issn=0167-4412 | doi=10.1007/s11103-021-01147-7 | pages=227–244| pmid=33825083 | pmc=8492783 | bibcode=2021PMolB.107..227B }}</ref><ref name="Sun-et-al-2020">{{cite journal | last1=Sun | first1=Guiling | last2=Bai | first2=Shenglong | last3=Guan | first3=Yanlong | last4=Wang | first4=Shuanghua | last5=Wang | first5=Qia | last6=Liu | first6=Yang | last7=Liu | first7=Huan | last8=Goffinet | first8=Bernard | last9=Zhou | first9=Yun | last10=Paoletti | first10=Mathieu | last11=Hu | first11=Xiangyang | last12=Haas | first12=Fabian B. | last13=Fernandez-Pozo | first13=Noe | last14=Czyrt | first14=Alia | last15=Sun | first15=Hang | last16=Rensing | first16=Stefan A. | last17=Huang | first17=Jinling | title=Are fungi-derived genomic regions related to antagonism towards fungi in mosses? | journal=[[New Phytologist]] | publisher=New Phytologist Foundation ([[Wiley publishing|Wiley]]) | volume=228 | issue=4 | date=2020-07-31 | issn=0028-646X | doi=10.1111/nph.16776 | pages=1169–1175 | pmid=32578878 | s2cid=220047618| doi-access=free | bibcode=2020NewPh.228.1169S }}</ref> Galotto ''et al.'', 2020 applied [[chitooctaose]] and found that tips detected and responded to this chitin derivative by changing [[gene expression]].<ref name="Delaux-Schornack-2021" /><ref name="Bibeau-et-al-2021" /><ref name="Sun-et-al-2020" /> They concluded that this defense response was probably [[conserved sequence|conserved]] from the [[most recent common ancestor]] of [[bryophyte]]s and [[tracheophytes]].<ref name="Delaux-Schornack-2021" /> Orr ''et al.'', 2020 found that the [[microtubule]]s of growing tip cells were structurally similar to [[F-actin]] and served a similar purpose.<ref name="Bibeau-et-al-2021" />

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 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 the fertilization distance.<ref name="vanderVelde2001">{{Cite journal|title = The reproductive biology of Polytrichum formosum: clonal structure and paternity revealed by microsatellites|last1 = van der Velde|first1 = M.|journal = Molecular Ecology|doi = 10.1046/j.0962-1083.2001.01385.x|pmid = 11742546|issue = 10|pages = 2423–2434|last2 = During|first2 = H. J.|last3 = van de Zande|first3 = L.|last4 = Bijlsma|first4 = R.|volume = 10|year = 2001| bibcode=2001MolEc..10.2423V |s2cid = 19716812}}</ref>

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 (Botany)|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 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.{{citation needed|date=April 2023}}

Most mosses rely on the wind to disperse the spores. In the [[genus]] ''[[Sphagnum]]'' the [[Sphagnum#Spore dispersal|spores are projected]] about {{Convert|10-20|cm|4 = 0|abbr = on}} off the ground by compressed air contained in the capsules; the spores are accelerated to about 36,000 times the [[Gravity of Earth|earth's gravitational acceleration ''g'']].<ref>{{cite journal|doi= 10.1126/science.1193047|author= Johan L. van Leeuwen |title= Launched at 36,000''g'' |journal=Science|pages= 395–6|issue= 5990 |volume= 329 |date= July 23, 2010|pmid= 20651138|s2cid= 206527957 }}</ref><ref>{{cite journal|doi= 10.1126/science.1190179|author1=Dwight K. Whitaker  |author2=Joan Edwards  |name-list-style=amp |title= ''Sphagnum'' Moss Disperses Spores with Vortex Rings |journal=Science|page= 406|issue= 5990 |volume= 329 |date= July 23, 2010|pmid= 20651145|bibcode=2010Sci...329..406W |s2cid=206526774 }}</ref>

[[File:Moss Gametophytes Sporophytes.JPG|thumb|300px|A patch of moss showing both gametophytes (the low, leaf-like forms) and sporophytes (the tall, stalk-like forms)]]

It has recently been found that microarthropods, such as [[springtails]] and [[mites]], can effect moss fertilization<ref name="cronberg2006">{{Cite journal | last1 = Cronberg | first1 = N. | last2 = Natcheva | first2 = R. | last3 = Hedlund | first3 = K. | doi = 10.1126/science.1128707 | title = Microarthropods Mediate Sperm Transfer in Mosses | journal = Science | volume = 313 | issue = 5791 | pages = 1255 | year = 2006 | pmid =  16946062| s2cid = 11555211 }}</ref> and that this process is mediated by moss-emitted scents. Male and female [[fire moss]], for example, emit different and complex volatile organic scents.<ref name="rosenstiel2012">{{Cite journal | last1 = Rosenstiel | first1 = T. N. | last2 = Shortlidge | first2 = E. E. | last3 = Melnychenko | first3 = A. N. | last4 = Pankow | first4 = J. F. | last5 = Eppley | first5 = S. M. | title = Sex-specific volatile compounds influence microarthropod-mediated fertilization of moss | doi = 10.1038/nature11330 | journal = Nature | volume = 489 | issue = 7416 | pages = 431–433 | year = 2012 | pmid =  22810584| bibcode = 2012Natur.489..431R | s2cid = 4419337 }}</ref> 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 a scent-mediated relationship analogous to the plant-pollinator relationship found in many seed plants.<ref name="rosenstiel2012" /> 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 is the favoured habitat of the species of this genus.<ref name=vaizey>{{cite journal | last1 = Vaizey | first1 = J. R. | year = 1890 | title = On the Morphology of the Sporophyte of ''Splachnum luteum'' | journal = Annals of Botany | volume = 1 | pages = 1–8 | doi = 10.1093/oxfordjournals.aob.a090623 }}</ref>

In many mosses, e.g., ''Ulota phyllantha'', green vegetative structures called [[gemma (botany)|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 [[cloning|clonal]] populations.

===Dwarf males===
Moss dwarf males (also known as [[nannandry]] or [[phyllodioicy]]) originate from wind-dispersed male [[spore]]s that settle and germinate on 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.<ref name="UneKouji">{{Cite journal|url = http://ir.lib.osaka-kyoiku.ac.jp/dspace/handle/123456789/2572|title = Sexual dimorphism in the Japanese species of Macromitrium Brid.(Musci: Orthotrichaceae)|last = Une|first = Kouji|journal = The Journal of the Hattori Botanical Laboratory Devoted to Bryology and Lichenology|pages = 487–513|year = 1985|volume = 59}}</ref> 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.<ref name="UneKouji" /><ref>{{Cite journal|title = The male gametophores of Leucobryum glaucum (Hedw.) Ångstr. and L. juniperoideum (Brid.) C. Muell. in two Welsh woodlands|last = Blackstock|first = T. H.|journal = Journal of Bryology|doi = 10.1179/jbr.1987.14.3.535|year = 1987|pages = 535–541|issue = 3|volume = 14| bibcode=1987JBryo..14..535B }}</ref><ref name="Loveland">{{Cite book|title = Sexual dimorphism in the moss genus Dicranum Hedw. (Dissertation)|last = Loveland|first = Hugh Frank|publisher = University of Michigan|year = 1956}}</ref><ref name="Wallace">{{Cite book|title = Developmental morphology and sexual dimorphism in Homalothecium megaptilum (Sull.) Robins. (Dissertation)|last = Wallace|first = M. H.|publisher = Washington State University|year = 1970}}</ref> In the latter case, dwarf males that are transplanted from females to another substrate develop into large shoots, suggesting that the females emit a substance which inhibits the growth of germinating males and possibly also quickens their onset of sexual maturation.<ref name="Loveland" /><ref name="Wallace" /> The nature of such a substance is unknown, but the phytohormone [[auxin]] may be involved<ref name="UneKouji" />

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 is positively associated with the presence of dwarf males in several [[phyllodioicy|phyllodioicous]] species.<ref>{{Cite journal|title = Studies of fertility of Dicranum majus in two populations with contrasted sporophyte production|last1 = Sagmo Solli|first1 = I. M.|journal = Journal of Bryology|doi =10.1179/jbr.2000.22.1.3 |year =1998 |pages =3–8 |issue =1 |volume = 22|last2 = Söderström|first2 = Lars|last3 = Bakken|first3 = Solveig|last4 = Flatberg|first4 = Kjell Ivar|last5 = Pedersen|first5 = Bård|s2cid = 85349694}}</ref><ref name="Hedenäs">{{Cite journal|title = The overlooked dwarf males in mosses—unique among green land plants|last1 = Hedenäs|first1 = Lars|journal = Perspectives in Plant Ecology, Evolution and Systematics|doi =10.1016/j.ppees.2011.03.001 |year = 2011|pages = 121–135|issue = 2|last2 = Bisang|first2 = Irene|volume = 13| bibcode=2011PPEES..13..121H }}</ref>

Dwarf males occur in several unrelated [[Lineage (evolution)|lineages]]<ref name="Hedenäs" /><ref>{{Cite journal|title = Sex determination in bryophytes|last1 = Ramsay|first1 = Helen P.|journal = Journal of the Hattori Botanical Laboratory|volume = 52|year = 1982|pages = 255–274|last2 = Berrie|first2 = G. K.}}</ref> and may be more common than previously thought.<ref name="Hedenäs" /> For example, it is estimated that between one quarter and half of all [[dioicy|dioicous]] [[pleurocarpous|pleurocarp]]s have dwarf males.<ref name="Hedenäs" />

===DNA repair===
The moss ''[[Physcomitrium patens]]'' has been used as a [[model organism]] to study how plants [[DNA repair|repair]] damage to their DNA, especially the repair mechanism known as [[homologous recombination]]. If the plant cannot repair DNA damage, e.g., [[double-strand breaks]], in their [[somatic cell]]s, 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.<ref name="pmid18079367">{{cite journal |last1=Rensing |first1=S.A. |last2=Lang |first2=D |last3=Zimmer |first3=A.D. |last4=Terry |first4=A. |last5=Salamov |first5=A |last6=Shapiro |first6=H. |last7=Nishiyama |first7=T. |last8=Sakakibara  |first8=K. |display-authors=7 |title=The Physcomitrella genome reveals evolutionary insights into the conquest of land by plants |journal=Science |volume=319 |issue=5859 |pages=64–9 | date=January 2008 |pmid=18079367 |doi=10.1126/science.1150646 |url=http://pubman.mpdl.mpg.de/pubman/item/escidoc:1221568/component/escidoc:1221567/rensing_et_al_science_2008.pdf|hdl=11858/00-001M-0000-0012-3787-A |bibcode=2008Sci...319...64R |s2cid=11115152 |hdl-access=free }}</ref> ''P. patens'' mutants that are defective in key steps of homologous recombination have been used to work out how 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.<ref name="pmid17921313">{{cite journal |vauthors=Markmann-Mulisch U, Wendeler E, Zobell O, Schween G, Steinbiss HH, Reiss B |title=Differential requirements for RAD51 in Physcomitrella patens and Arabidopsis thaliana development and DNA damage repair |journal=Plant Cell |volume=19 |issue=10 |pages=3080–9 | date=October 2007 |pmid=17921313 |pmc=2174717 |doi=10.1105/tpc.107.054049 |bibcode=2007PlanC..19.3080M }}</ref> Similarly, studies of mutants defective in ''Ppmre11'' or ''Pprad50'' (that encode key proteins of the [[MRN complex]], 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.<ref name="pmid22210882">{{cite journal |vauthors=Kamisugi Y, Schaefer DG, Kozak J, Charlot F, Vrielynck N, Holá M, Angelis KJ, Cuming AC, Nogué F |title=MRE11 and RAD50, but not NBS1, are essential for gene targeting in the moss Physcomitrella patens |journal=Nucleic Acids Res. |volume=40 |issue=8 |pages=3496–510 | date=April 2012 |pmid=22210882 |pmc=3333855 |doi=10.1093/nar/gkr1272 }}</ref>

==Classification==
More recently, mosses have been grouped with the [[Marchantiophyta|liverworts]] and [[hornwort]]s in the division '''Bryophyta''' ([[bryophyte]]s, or Bryophyta ''sensu lato'').<ref name=Sousa2019/><ref name=CoxLiFostEmbl14>{{cite journal |title=Conflicting Phylogenies for Early Land Plants are Caused by Composition Biases among Synonymous Substitutions |last1 = Cox |first1=Cymon J. |display-authors=etal |journal=Systematic Biology |volume=63 |issue=2 |year=2014 |pages=272–279 |doi=10.1093/sysbio/syt109
|pmid = 24399481 |pmc=3926305 }}</ref><!--<ref name=Puttick2018>{{cite journal |title=The Interrelationships of Land Plants and the Nature of the Ancestral Embryophyte |last1 = Puttick |first1 = Mark N. |display-authors=etal |journal=Current Biology |volume=28 |issue=5 |year=2018 |pages=733–745.e2 |doi=10.1016/j.cub.2018.01.063
|pmid = 29456145 |hdl=1983/ad32d4da-6cb3-4ed6-add2-2415f81b46da |s2cid = 3269165 |hdl-access=free }}</ref><ref name=Leebens-Mack2019>{{cite journal |title=One thousand plant transcriptomes and the phylogenomics of green plants |last1 = Leebens-Mack |first1 = James H. |display-authors=etal |journal=Nature |volume=574 |pages=679–685 |year=2019 |issue = 7780 |doi =10.1038/s41586-019-1693-2
|pmid = 31645766 |pmc=6872490 }}</ref><ref name=Zhang2020>{{cite journal |title=The hornwort genome and early land plant evolution |last1 = Zhang |first1 = Jian |display-authors=etal |journal=Nature Plants |volume=6 |pages=107–118 |year=2020 |issue = 2 |doi=10.1038/s41477-019-0588-4
|pmid = 32042158 |pmc=7027989 }}</ref><ref name=Harris2020>{{cite journal |title=Phylogenomic Evidence for the Monophyly of Bryophytes and the Reductive Evolution of Stomata |last1 = Harris |first1 = Brogan J. |display-authors=etal |journal=Current Biology |volume=30 |issue=11 |pages=P2201–2012.E2 |year=2020 |doi=10.1016/j.cub.2020.03.048
|pmid = 32302587 |hdl=1983/fbf3f371-8085-4e76-9342-e3b326e69edd |s2cid = 215798377 |hdl-access=free }}</ref><ref name=Li2020>{{cite journal |title=Anthoceros genomes illuminate the origin of land plants and the unique biology of hornworts |last1 = Li |first1 = Fay-Wei |display-authors=etal |journal= Nature Plants |volume=6 |pages=259–272 |year=2020 |issue = 3 |doi=10.1038/s41477-020-0618-2
|pmid = 32170292 |pmc = 8075897 |hdl=10261/234303 |hdl-access=free }}</ref><ref name=Sousa2020a>{{cite journal |title=The Chloroplast Land Plant Phylogeny: Analyses Employing Better-Fitting Tree- and Site-Heterogeneous Composition Models |last1 = Sousa |first1 = Filipe |display-authors=etal |journal = Frontiers in Plant Science |volume=11 |page=1062 |year=2020 |doi=10.3389/fpls.2020.01062
|pmid = 32760416 |pmc = 7373204 |doi-access = free }}</ref><ref name="Su2021">{{cite journal |title=Large-Scale Phylogenomic Analyses Reveal the Monophyly of Bryophytes and Neoproterozoic Origin of Land Plants |last1 = Su |first1 = Danyan |display-authors=etal |journal = Molecular Biology and Evolution |year=2021 |volume = 38 |issue = 8 |pages = 3332–3344 |doi=10.1093/molbev/msab106|pmid = 33871608 |pmc=8321542 }}</ref>{{Excessive citations inline|date=October 2021}}--> The bryophyte division itself contains three (former) divisions: Bryophyta (mosses), [[Marchantiophyta]] (liverworts) and [[hornworts|Anthocerotophyta]] (hornworts); it has been proposed that these latter divisions are de-ranked to the classes Bryopsida, Marchantiopsida, and Anthocerotopsida, respectively.<ref name=Sousa2019 /> The mosses and liverworts are now considered to belong to a clade called [[Setaphyta]].<ref name=Puttick2018>{{cite journal |title=The Interrelationships of Land Plants and the Nature of the Ancestral Embryophyte |last1 = Puttick |first1 = Mark N. |display-authors=etal |journal=Current Biology |volume=28 |issue=5 |year=2018 |pages=733–745.e2 |doi=10.1016/j.cub.2018.01.063
|pmid = 29456145 |bibcode = 2018CBio...28E.733P |hdl=1983/ad32d4da-6cb3-4ed6-add2-2415f81b46da |s2cid = 3269165 |hdl-access=free }}</ref><ref name=Sousa2020b>{{cite journal |title=The mitochondrial phylogeny of land plants shows support for Setaphyta under composition-heterogeneous substitution models |last1=Sousa |first1=Filipe |display-authors=etal |journal=PeerJ |year=2020 |volume=8 |issue=4 |page=e8995 |doi=10.7717/peerj.8995|pmid=32377448 |pmc=7194085 |doi-access=free }}</ref><ref name=Cox2018>{{cite journal |title=Land Plant Molecular Phylogenetics: A Review with Comments on Evaluating Incongruence Among Phylogenies |journal=Critical Reviews in Plant Sciences |last=Cox |first=Cymon J. |year=2018 |volume=37 |issue=2–3 |pages=113–127 |doi=10.1080/07352689.2018.1482443|bibcode=2018CRvPS..37..113C |hdl=10400.1/14557 |s2cid=92198979 |hdl-access=free }}</ref>

The mosses, (Bryophyta sensu stricto), are divided into eight classes:

{|  style="float:left; text-align:left; padding:2.5px; background:#eef;"
|-
| style="background:#fff; padding:2.5px" |division '''Bryophyta'''
: class [[Takakiopsida]]
: class [[Sphagnopsida]]
: class [[Andreaeopsida]]
: class [[Andreaeobryopsida]]
: class [[Oedipodiopsida]]
: class [[Polytrichopsida]]
: class [[Tetraphidopsida]]
: class [[Bryopsida]]
|{{clade| style=font-size:75%;line-height:75%
|1={{clade 
 |1=''[[vascular plant]]s''
  |2={{clade
   |1=''[[Anthocerotopsida|hornworts]]''
   |2={{clade
    |1=''[[Marchantiophyta|liverworts]]''
    |label2='''Bryophyta'''
    |2={{clade
     |1=[[Takakiopsida]]
     |2=[[Sphagnopsida]]
     |3={{clade
      |1=[[Andreaeopsida]]
      |2=[[Andreaeobryopsida]]
      |label3=Neomusci
      |3={{clade
       |1=[[Oedipodiopsida]]
       |label2=Cenomusci
       |2={{clade
        |1=[[Polytrichopsida]]
        |label2=Altamusci
        |2={{clade
         |1=[[Tetraphidopsida]]
         |2=[[Bryopsida]]
        }}
       }}
      }}
     }}
    }}
   }}
  }}
 }}
}}
|- style="font-size:90%;"
| colspan=2 | The current [[phylogenetics|phylogeny]] and composition of the Bryophyta.<ref name="Goffinet & Buck 2004"/><ref>Buck, William R. & Bernard Goffinet. (2000). "Morphology and classification of mosses", pages 71–123 ''in'' A. Jonathan Shaw & Bernard Goffinet (Eds.), ''Bryophyte Biology''. (Cambridge: Cambridge University Press). {{ISBN|0-521-66097-1}}.</ref>
|}{{Clear}}

[[File:Haeckel Muscinae.jpg|thumb|"Muscinae" from [[Ernst Haeckel]]'s ''[[Kunstformen der Natur]]'', 1904]]
Six of 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, 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 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 {{Convert|40|cm|abbr = on}} high. The tallest land moss, a member of the Polytrichidae is probably ''[[Dawsonia superba]]'', a native to [[New Zealand]] and other parts of [[Australasia]].

==Geological history==
[[File:RedMoss.jpg|thumb|right|[[Polytrichum piliferum|Bristly Haircap]] moss, a winter native of the [[Yorkshire Dales]] [[moorland]]]]
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.<ref name=Thomas1972>{{cite journal
 | author = Thomas, B.A.
 | year = 1972
 | title = A probable moss from the Lower Carboniferous of the Forest of Dean, Gloucestershire
 | journal = Annals of Botany
 | volume = 36
 | issue = 1
 | pages = 155–161
 | issn = 1095-8290
 | jstor= 42752024
| doi = 10.1093/oxfordjournals.aob.a084568
 }}</ref> It has further been claimed that tube-like fossils from the [[Silurian]] are the macerated remains of moss [[calyptræ]].<ref>{{cite journal |last=Kodner |first=R. B. |author2=Graham, L. E. |year=2001 |title=High-temperature, acid-hydrolyzed remains of ''Polytrichum'' (Musci, Polytrichaceae) resemble enigmatic Silurian-Devonian tubular microfossils |journal=American Journal of Botany |volume=88 |issue=3 |pages=462–466 |doi=10.2307/2657111 |pmid=11250824 |jstor=2657111 }}</ref> Mosses also appear to evolve 2–3 times slower than ferns, [[gymnosperm]]s and [[angiosperm]]s.<ref>{{cite journal |title=Slow molecular evolution in 18S rDNA, ''rbcL'' and ''nad5'' genes of mosses compared with higher plants |journal=Journal of Evolutionary Biology |date=2008 |last1=Stenøien |first1=H. K. |doi=10.1111/j.1420-9101.2007.01479.x |volume=21 |issue = 2|pages=566–571 |pmid=18205784 |doi-access=free }}</ref>

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&nbsp;million years ago, they absorbed CO<sub>2</sub> from the atmosphere and extracted minerals by secreting organic acids that dissolved the rocks they were growing on. These chemically altered rocks in turn reacted with the atmospheric CO<sub>2</sub> 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 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<sub>2</sub> dropped all over the world, allowing the formation of ice caps on the poles.<ref>{{cite web |url=https://www.newscientist.com/article/dn21417-first-land-plants-plunged-earth-into-ice-age.html |title=First land plants plunged Earth into ice age |publisher=Newscientist.com |access-date=2013-09-11 |url-status=live |archive-url=https://web.archive.org/web/20130923230406/http://www.newscientist.com/article/dn21417-first-land-plants-plunged-earth-into-ice-age.html |archive-date=2013-09-23 }}</ref><ref>{{cite web |url=https://www.sciencedaily.com/releases/2012/02/120201094923.htm |title=First Plants Caused Ice Ages, New Research Reveals |publisher=Sciencedaily.com |date=2012-02-01 |access-date=2013-09-11 |url-status=live |archive-url=https://web.archive.org/web/20131003153329/https://www.sciencedaily.com/releases/2012/02/120201094923.htm |archive-date=2013-10-03 }}</ref>

==Ecology==

===Habitat===
<gallery mode="packed">
File:Mossopolis.jpg|Dense moss colonies in a cool coastal forest
File:MossForest.jpg|A cool high altitude/latitude moss forest; the forest floor is covered in moss, beneath conifers
File:Route 1 , Between Vik and Kirkjubæjarklaustur - panoramio (7).jpg|Moss colonizes a [[basalt]] flow, in [[Iceland]]
File:Moss (Iceland) 03.jpg|Moss growing along [[seep]]s and springs in newly deposited [[basaltic]] rock, Iceland.
File:Steinerne Rinne bei Obererasbach im Altmühltal.jpg|Moss growing along the stream from a [[karst spring]]; [[travertine]] deposits from the stream water and the moss overgrows it, forming this ridge, with the stream on top.
File:Winter moss.jpg|Moss with sporophytes on brick
File:Mech plonnik mlode sporofity.jpg|Young [[sporophyte]]s of the common moss ''Tortula muralis'' (wall screw-moss)
File:Taiwan 2009 JinGuaShi Historic Gold Mine Moss Covered Retaining Wall FRD 8940.jpg|[[Retaining wall]] covered in moss
File:Michiganmosspatch.jpg|A small clump of moss beneath a conifer (a shady, usually dry place)
File:MossOnConcreteWall.jpg|Moss on a concrete wall
File:Moss (Bryophyta) on the forest floor in Broken Bow, Oklahoma.jpg|Moss (Bryophyta) on the forest floor in Broken Bow, Oklahoma
</gallery>

Mosses live in almost every terrestrial habitat type on Earth.<ref>{{cite journal |last1=Medina |first1=Nagore G. |last2=Draper |first2=Isabel |last3=Lara |first3=Francisco |title=Biogeography of mosses and allies: does size matter? |journal=Biogeography of Microscopic Organisms. Is Everything Small Everywhere |date=2011 |pages=209–233|doi=10.1017/CBO9780511974878.012 |isbn=978-0-521-76670-8 }}</ref><ref>{{cite journal |last1=Eldridge |first1=David J. |title=The global contribution of soil mosses to ecosystem services |journal=Nature Geoscience |date=2023 |volume=16 |issue=5 |pages=430–438|doi=10.1038/s41561-023-01170-x |bibcode=2023NatGe..16..430E |hdl=10261/308895 |hdl-access=free }}</ref> Though mosses are particularly abundant in certain habitats such as peatlands, where Sphagnum mosses are the dominant organism, and in moist boreal, temperate, and montane tropical forests, mosses grow in many other habitats, including habitats with conditions too extreme for [[Tracheophyte|vascular plants]] to survive. Desiccation tolerant mosses are important in arid and semi-arid ecosystems,<ref>{{cite journal |last1=Silva |first1=Anderson T. |title=To dry perchance to live: Insights from the genome of the desiccation-tolerant biocrust moss Syntrichia caninervis |journal=The Plant Journal |date=2020 |volume=105 |issue=5 |pages=1339–1356 |doi=10.1111/tpj.15116 |pmid=33277766 }}</ref><ref>{{cite journal |last1=Coe |first1=Kirsten K. |last2=Sparks |first2=Jed P. |last3=Belnap |first3=Jayne |title=Physiological Ecology of Dryland Biocrust Mosses |journal=Photosynthesis in Bryophytes and Early Land Plants |date=2013 |pages=291–308}}</ref> where they help form [[biocrust]]s that mediate extremes of soil temperature,<ref>{{cite journal |last1=Xiao |first1=Bo |last2=Ma |first2=Shuang |last3=Hu |first3=Kelin |title=Moss biocrusts regulate surface soil thermal properties and generate buffering effects on soil temperature dynamics in dryland ecosystem |journal=Geoderma |date=2019 |volume=351 |pages=9–24|doi=10.1016/j.geoderma.2019.05.017 |bibcode=2019Geode.351....9X }}</ref> regulate soil moisture,<ref>{{cite journal |last1=Dollery |first1=Rebecca |last2=Bowie |first2=Mike H. |last3=Dickinson |first3=Nicholas M. |title=The ecological importance of moss ground cover in dry shrubland restoration within an irrigated agricultural landscape matrix |journal=Ecology and Evolution |date=2022 |volume=12 |issue=4|pages=e8843 |doi=10.1002/ece3.8843 |pmid=35475181 |pmc=9034467 |bibcode=2022EcoEv..12E8843D |hdl=10182/15051 }}</ref> and regulate the release and uptake of carbon.<ref>{{cite journal |last1=Wu |first1=Lin |last2=Zhang |first2=Yuanming |last3=Zhang |first3=Jing |last4=Downing |first4=Alison |title=Precipitation intensity is the primary driver of moss crust-derived CO2 exchange: Implications for soil C balance in a temperate desert of northwestern China |journal=European Journal of Soil Biology |date=2015 |volume=67 |pages=27–34|doi=10.1016/j.ejsobi.2015.01.003 }}</ref> Mosses can live on substrates heated by geothermal activity to temperatures exceeding 50 degrees Celsius,<ref>{{cite journal |last1=Garcia |first1=Estefania Llaneza |last2=Rosenstiel |first2=Todd N. |last3=Graves |first3=Camille |last4=Shortlidge |first4=Erin E. |last5=Eppley |first5=Sarah M. |title=Distribution drivers and physiological responses in geothermal bryophyte communities |journal=American Journal of Botany |date=2016 |volume=103 |issue=4|pages=625–634 |doi=10.3732/ajb.1500422 |pmid=27022007 }}</ref> on walls and pavement in urban areas,<ref>{{cite journal |last1=Lundholm |first1=Jeremy |title=Vegetation of Urban Hard Surfaces |journal=Urban Ecology |date=2011 |pages=93–102 |doi=10.1093/acprof:oso/9780199563562.003.0012|isbn=978-0-19-956356-2 }}</ref> and in Antarctica.<ref>{{cite journal |last1=Yin |first1=Hao |last2=Perera-Castro |first2=Alicia V. |last3=Randall |first3=Krystal L. |last4=Turnbull |first4=Johanna D. |last5=Waterman |first5=Melinda J. |last6=Dunn |first6=Jodie |last7=Robinson |first7=Sharon A. |title=Basking in the sun: how mosses photosynthesise and survive in Antarctica |journal=Photosynthesis Research |date=2023 |volume=158 |issue=2 |pages=151–169|doi=10.1007/s11120-023-01040-y |pmid=37515652 |pmc=10684656 |bibcode=2023PhoRe.158..151Y }}</ref> Moss diversity is generally not associated with latitude; boreal and temperate moss diversity is similar to tropical moss diversity. Moss diversity hotspots are found in the northern Andes mountains, Mexico, the Himalayan mountains, Madagascar, Japan, the highlands of eastern Africa, Southeast Asia, central Europe, Scandinavia, and British Columbia.<ref>{{cite journal |last1=Geffert |first1=Jan Laurens |last2=Frahm |first2=Jan-Peter |last3=Barthlott |first3=Wilhelm |last4=Mutke |first4=Jens |title=Global moss diversity: spatial and taxonomic patterns of species richness |journal=Journal of Bryology |date=2013 |volume=35 |issue=1 |pages=1–11|doi=10.1179/1743282012Y.0000000038 |bibcode=2013JBryo..35....1G }}</ref>

Moss [[gametophyte]]s are [[autotroph]]ic and require [[sunlight]] to perform [[photosynthesis]].<ref name=moss>{{cite book |last=Kimmerer |first=Robin Wall |title=Gathering Moss |year=2003 |publisher=Oregon State University Press |location=Corvallis, Oregon |isbn=978-0-87071-499-3}}</ref> In most areas, mosses grow chiefly in moist, shaded areas, such as wooded areas and at the edges of streams, but [[shade (shadow)|shade]] tolerance varies by species. 

Different moss species grow on different substrates 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 [[humus]]y soil, downed logs, burnt stumps, tree trunk bases, upper tree trunks, and tree branches or in [[bog]]s. Moss species growing on or under trees are often specific about the species of trees they grow on, such as preferring [[Pinophyta|conifers]] over [[broad-leaved tree|broadleaf trees]], [[oak]]s over [[alder]]s, or vice versa.<ref name=pojar /> 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]]'', 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.<ref name=pojar>{{cite book|last=Pojar and MacKinnon|title=Plants of the Pacific Northwest Coast|year=1994|publisher=Lone Pine Publishing|location=Vancouver, British Columbia|isbn=978-1-55105-040-9}}</ref> Such aquatic or semi-aquatic mosses can greatly exceed the normal range of lengths seen in terrestrial mosses. Individual plants {{Convert|20-30|cm|4 = 0|abbr = on}} 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.<ref>{{Cite journal|url=https://nph.onlinelibrary.wiley.com/doi/full/10.1046/j.0028-646x.2001.00334.x|title=Selection pressures on stomatal evolution|first=John A.|last=Raven|date=19 December 2002|journal=New Phytologist|volume=153|issue=3|pages=371–386|via=Wiley Online Library|doi=10.1046/j.0028-646X.2001.00334.x|pmid=33863217 |bibcode=2002NewPh.153..371R }}</ref>

Wherever they occur, mosses require liquid water for at least part of the year to complete fertilisation. Many mosses can survive [[desiccation]], sometimes for months, returning to life within a few hours of rehydration.<ref name=moss /> Mosses in arid habitats, such as the moss ''[[Syntrichia caninervis]]'', have adaptations for collecting non-rainfall sources of moisture like [[dew]] and [[fog]], capturing condensation from the air.<ref>{{cite journal |last1=de Guevara |first1=Monica Ladrón |last2=Maestre |first2=Fernando T |title=Ecology and responses to climate change of biocrust-forming mosses in drylands |journal=Journal of Experimental Botany |date=2022 |volume=73 |issue=13 |pages=4380–4395|doi=10.1093/jxb/erac183 |pmid=35553672 |pmc=9291340 }}</ref>

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.<ref>{{cite book |last1=Porley |first1=Ron |last2=Hodgetts |first2=Nick |year=2005 |title=Mosses & Liverworts |location=London |publisher=Collins  |isbn=978-0-00-220212-1 |pages=80–81}}</ref> The reason is assumed to be because [[sunlight|sunshine]] on the south side causes a dry environment. The reverse would be true in the [[Southern Hemisphere]]. Some naturalists feel that mosses grow on the damper side of trees and rocks.<ref name=mathews>{{cite book |last=Mathews |first=Daniel |title=Cascade-Olympic Natural History |year=1994 |publisher=[[Audubon Society]] of Portland/Raven Editions |location=Portland, Oregon |isbn=978-0-9620782-0-0 |url-access=registration |url=https://archive.org/details/cascadeolympicna00math}}</ref> In some cases, such as sunny climates in [[temperate climate|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 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.<ref name=handbook>{{cite book |last1=Fletcher |first1=Michael |title=Moss Growers Handbook |date=2006 |publisher=SevenTy Press |location=Reading Berkshire |isbn=0-9517176-0-X |edition=3rd |url=https://archive.org/details/MossGrowersHandbook/mode/2up}}</ref>

===Relationship with cyanobacteria===
In [[taiga|boreal forests]], some species of moss play an important role in providing nitrogen for the ecosystem due to their relationship with [[nitrogen fixation|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.<ref>{{Cite journal|last1=Rousk|first1=Kathrin|last2=Jones|first2=Davey L.|last3=DeLuca|first3=Thomas H.|date=2013-01-01|title=Moss-cyanobacteria associations as biogenic sources of nitrogen in boreal forest ecosystems|journal=Frontiers in Microbiology|language=en|volume=4|pages=150|doi=10.3389/fmicb.2013.00150|issn=1664-302X|pmc=3683619|pmid=23785359|doi-access=free}}</ref>

==Cultivation==
[[File:500px photo (189849595).jpeg|thumb|A moss lawn in a temple garden in [[Kyoto]], Japan]]
[[File:Moss Garden, Bloedel Reserve.jpg|thumb|The moss garden at the Bloedel Reserve, Bainbridge Island, Washington State.]]
{{main|Moss lawn}}

Moss is often considered a [[weed]] in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by [[Japanese garden]]ing. 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.<ref>{{cite book|last=Chan|first=Peter|title=Bonsai Masterclass|year=1993|publisher=Sterling Publishing Co.|location=New York City|isbn=978-0-8069-6763-9}}</ref> Rules of cultivation are not widely established. Moss collections are quite often begun using samples transplanted from 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 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 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.<ref name="problem solver">{{cite book|last=Smith|first=Sally W.|title=Sunset Western Garden Problem Solver|year=1998|publisher=Sunset Books|location=Menlo Park, California|isbn=978-0-376-06132-4|url-access=registration|url=https://archive.org/details/westerngardenpro00suns}}</ref> 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.<ref name=moss /> The [[Bloedel Reserve]] on Bainbridge Island, Washington State, 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.<ref>{{cite web|title=The Bloedel Reserve|url=http://www.bloedelreserve.org/|access-date=24 April 2011|url-status=live|archive-url=https://web.archive.org/web/20110416035711/http://www.bloedelreserve.org/|archive-date=16 April 2011}}</ref>

=== Green roofs and walls ===
[[File:Green Roof - geograph.org.uk - 544737.jpg|thumb|Red moss, possibly ''[[Ceratodon purpureus]]'', cultivated on a [[green roof]]]]
Mosses are sometimes used in [[green roof]]s. 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 the local climate, mosses in green roofs require no irrigation once established and are low maintenance.<ref>{{cite web|title=RoofTopGarden|url=http://rooftopgarden.com/category/green-roof/|access-date=22 May 2011|url-status=dead|archive-url=https://web.archive.org/web/20110424045647/http://rooftopgarden.com/category/green-roof/|archive-date=24 April 2011}}</ref> Mosses are also used on [[green wall]]s.

=== Mossery ===
A passing fad for moss-collecting in the late 19th century led to the establishment of mosseries in many British and American gardens. The mossery is typically constructed out of slatted wood, with a flat roof, open to the north side (maintaining shade). Samples of moss were installed in the cracks between wood slats. The whole mossery would then be regularly moistened to maintain growth.

=== Aquascaping ===
[[Aquascaping]] uses many aquatic mosses. They do best at low nutrient, light, and heat levels, and propagate fairly readily. They help maintain a water chemistry suitable for aquarium fish.<ref name=aquascaping>{{cite web |title=A Guide to Keeping and Growing Aquatic Moss |url=https://aquascapinglove.com/basics/guide-keeping-growing-aquatic-moss/ |website=Aquascaping Love |date=12 April 2016}}</ref> They grow more slowly than many aquarium plants, and are fairly hardy.<ref>{{cite web |title=Mosses |url=https://www.aquasabi.com/aquascaping-wiki_aquatic-plants_mosses |website=www.aquasabi.com |language=en}}</ref>

===Growth inhibition===
Moss can be a troublesome weed in containerized nursery operations and greenhouses.<ref>{{cite journal|last=Haglund|first=William A.|author2=Russell and Holland|title=Moss Control in Container-Grown Conifer Seedlings|journal=Tree Planter's Notes(USFS)|date=Summer 1981|volume=32|issue=3|pages=27–29|url=http://www.rngr.net/publications/tpn/32-3/32_3_27_29.pdf|access-date=24 April 2011|url-status=live|archive-url=https://web.archive.org/web/20110719113102/http://www.rngr.net/publications/tpn/32-3/32_3_27_29.pdf|archive-date=19 July 2011}}</ref> Vigorous moss growth can inhibit seedling emergence and penetration of water and fertilizer to the plant roots.

Moss growth can be inhibited by a number of methods:
* Decreasing availability of [[water]] through [[drainage]].
* Increasing direct sunlight.
* Increasing number and resources available for competitive plants like [[grass]]es.
* Increasing the [[soil pH]] with the application of [[Lime (mineral)|lime]].
* Heavy traffic or manually disturbing the moss bed with a rake
* Application of chemicals such as [[ferrous sulfate]] (e.g., in lawns) or bleach (e.g., on solid surfaces).
* In containerized nursery operations, coarse mineral materials such as sand, gravel, and rock chips are used as a fast-draining top dressing in plant containers to discourage moss growth.

The application of products containing ferrous sulfate or [[ferrous ammonium sulfate]] will kill moss; these ingredients are typically in commercial moss control products and [[fertilizer]]s. [[Sulfur]] and [[iron]] are [[essential nutrient]]s for some competing plants like grasses. Killing moss will not prevent regrowth unless conditions favorable to their growth are changed.<ref>{{cite web
 |author1     = Steve Whitcher
 |author2     = Master Gardener
 |title       = Moss Control in Lawns
 |work        = Gardening in Western Washington
 |publisher   = Washington State University
 |year        = 1996
 |url         = http://gardening.wsu.edu/library/lawn003/lawn003.htm
 |access-date  = 2007-02-10
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20070205225446/http://gardening.wsu.edu/library/lawn003/lawn003.htm
 |archive-date = 2007-02-05
}}</ref>

==Uses==
[[File:Moss on a wall @ Kanjirappally.jpg|thumb|Wall covered in moss]]

===Traditional===
Preindustrial societies made use of the mosses growing in their areas.

[[Sámi peoples|Sámi]] people, [[Indigenous peoples of the Americas|North American tribes]], and other [[circumpolar peoples]] used mosses for bedding.<ref name=mathews /><ref name=moss /> Mosses have also been used as insulation both for dwellings and in clothing. Traditionally, dried moss was used in some Nordic countries and Russia as an insulator between logs in [[log cabin]]s, and tribes of the northeastern United States and southeastern Canada used moss to fill chinks in wooden longhouses.<ref name=moss /> Circumpolar and alpine peoples have used mosses for insulation in boots and mittens. [[Ötzi the Iceman]] had moss-packed boots.<ref name=moss />

The capacity of dried mosses to absorb fluids has made their use practical in both medical and culinary uses. North American tribal people used mosses for diapers, wound dressing, and menstrual fluid absorption.<ref name=moss /> Tribes of the Pacific Northwest in the United States and Canada used mosses to clean salmon prior to drying it, and packed wet moss into pit ovens for steaming [[Camassia|camas]] bulbs. Food storage baskets and boiling baskets were also packed with mosses.<ref name=moss />

Recent research investigating the Neanderthals remains recovered from El Sidrón have provided evidence that their diet would have consisted primarily of pine nuts, moss and mushrooms. This is contrasted by evidence from other European locations, which point to a more carnivorous diet.<ref>{{Cite journal | doi=10.1038/nature21674| pmid=28273061| title=Neanderthal behaviour, diet, and disease inferred from ancient DNA in dental calculus| journal=Nature| volume=544| issue=7650| pages=357–361| year=2017| last1=Weyrich| first1=Laura S.| last2=Duchene| first2=Sebastian| last3=Soubrier| first3=Julien| last4=Arriola| first4=Luis| last5=Llamas| first5=Bastien| last6=Breen| first6=James| last7=Morris| first7=Alan G.| last8=Alt| first8=Kurt W.| last9=Caramelli| first9=David| last10=Dresely| first10=Veit| last11=Farrell| first11=Milly| last12=Farrer| first12=Andrew G.| last13=Francken| first13=Michael| last14=Gully| first14=Neville| last15=Haak| first15=Wolfgang| last16=Hardy| first16=Karen| last17=Harvati| first17=Katerina| last18=Held| first18=Petra| last19=Holmes| first19=Edward C.| last20=Kaidonis| first20=John| last21=Lalueza-Fox| first21=Carles| last22=de la Rasilla| first22=Marco| last23=Rosas| first23=Antonio| last24=Semal| first24=Patrick| last25=Soltysiak| first25=Arkadiusz| last26=Townsend| first26=Grant| last27=Usai| first27=Donatella| last28=Wahl| first28=Joachim| last29=Huson| first29=Daniel H.| last30=Dobney| first30=Keith| display-authors=29| hdl=10261/152016| bibcode=2017Natur.544..357W| s2cid=4457717| url=https://radar.brookes.ac.uk/radar/file/d6689cb0-38fa-4d3e-98e4-c8be2bd0263e/1/weyrich2017reconstructing.pdf}}</ref>

In [[Finland]], peat mosses have been used to make bread during [[famines]].<ref>Engman, Max; D. G. Kirby (1989). ''Finland: people, nation, state''. C. Hurst & Co. p. 45. {{ISBN|0-253-32067-4}}.</ref>

===Commercial===
[[File:Bioreaktor quer2.jpg|thumb|right|[[Moss bioreactor]] cultivating the moss ''[[Physcomitrella patens]]'']]

There is a substantial market in mosses gathered from the wild. The uses for intact moss are principally in the [[Flower|florist]] trade and for home decoration. Decaying moss in the genus ''Sphagnum'' is also the major component of [[peat]], which is "mined" for use as a [[fuel]], as a [[Horticulture|horticultural]] soil additive, and in smoking [[malt]] in the production of [[Scotch whisky]].

''[[Sphagnum]]'' moss, generally the species ''S. cristatum'' and ''S. subnitens'', is harvested while still growing and is dried out to be used in nurseries and horticulture as a plant growing medium.

Some ''Sphagnum'' mosses can absorb up to 20 times their own weight in water.<ref name=ABGSW>{{Cite web|url=https://www.anbg.gov.au/cryptogams/underworld/panel-10/index.html|archiveurl=https://web.archive.org/web/20140217122603/https://www.anbg.gov.au/cryptogams/underworld/panel-10/index.html|url-status=dead|title=The Plant Underworld - Australian Plant Information|first=Parks Australia|last=Australian National Botanic Gardens|archivedate=17 February 2014|website=www.anbg.gov.au}}</ref> In [[World War I]], ''Sphagnum'' mosses were used as first-aid dressings on soldiers' wounds, as these mosses said to absorb liquids three times faster than cotton, retain liquids better, better distribute liquids uniformly throughout themselves, and are cooler, softer, and be less irritating.<ref name=ABGSW/> It is also claimed to have antibacterial properties.<ref>{{Cite journal|last1=Stalheim|first1=T.|last2=Ballance|first2=S.|last3=Christensen|first3=B. E.|last4=Granum|first4=P. E.|date=2009-03-01|title=Sphagnan – a pectin-like polymer isolated from Sphagnum moss can inhibit the growth of some typical food spoilage and food poisoning bacteria by lowering the pH|journal=Journal of Applied Microbiology|language=en|volume=106|issue=3|pages=967–976|doi=10.1111/j.1365-2672.2008.04057.x|pmid=19187129|s2cid=1545021|issn=1365-2672}}</ref> [[Indigenous peoples of the Americas|Native Americans]] were one of the peoples to use ''Sphagnum'' for diapers and [[menstrual pad]]s, which is still done in [[Canada]].<ref>{{cite journal | author=Hotson, J. W. | title= Sphagnum Used as Surgical Dressing in Germany during the World War (Concluded) | journal=The Bryologist | pages=89–96 | issue=6 | volume=24 | year=1921 | jstor = 3237483 | doi=10.1639/0007-2745(1921)24[89:suasdi]2.0.co;2}}</ref>

In rural [[United Kingdom|UK]], ''[[Fontinalis antipyretica]]'' was traditionally used to extinguish fires as it could be found in substantial quantities in slow-moving rivers and the moss retained large volumes of water which helped extinguish the flames. This historical use is reflected in its [[Binomial nomenclature|specific]] [[Latin]]/[[Greek language|Greek]] name, which means "against fire".

In [[Mexico]], moss is used as a [[Christmas in Mexico|Christmas]] decoration.

''[[Physcomitrium patens]]'' is increasingly used in [[biotechnology]]. Prominent examples are the identification of moss [[gene]]s
with implications for [[crop]] improvement or human [[health]]<ref>[[Ralf Reski]] and Wolfgang Frank (2005): Moss (''[[Physcomitrella patens]])'' [[functional genomics]] – Gene discovery and tool development with implications for crop plants and human health. Briefings in Functional Genomics and [[Proteomics]] 4, 48–57.</ref> and the safe production of complex [[biopharmaceuticals]] in the moss [[bioreactor]], developed by [[Ralf Reski]] and his co-workers.<ref>{{cite journal |last1=Decker |first1=E. L. |last2=Reski |first2=R. |title=Moss bioreactors producing improved biopharmaceuticals |journal=Current Opinion in Biotechnology |date=2007 |volume=18 |issue=5 |pages=393–398 |doi=10.1016/j.copbio.2007.07.012 |pmid=17869503}}</ref>

London installed several structures called "City Trees": moss-filled walls, each of which is claimed to have "the air-cleaning capability of 275 regular trees" by consuming nitrogen oxides and other types of air pollution and producing oxygen.<ref>{{cite web |last=Landon |first=Alex |url=https://secretldn.com/city-trees-london-pollution/ |title=City Trees: London Has New Artificial Trees That Eat Pollution |date=2020-01-07 |website=Secret London |access-date=2020-02-09}}</ref>

==References==
{{Reflist}}

== Further reading ==
* [[Robin Wall Kimmerer|Kimmerer, Robin Wall]] (2003). ''Gathering Moss: A Natural and Cultural History of Mosses''. Oregon State University Press. {{ISBN|0-87071-499-6}}.

==External links==
{{Commons category|Bryophyta}}
{{Wikispecies|Bryophyta}}
{{wiktionary|moss}}
* [https://web.archive.org/web/20130206152227/http://www.hcs.ohio-state.edu/hcs300/liver2.htm Information, diagrams and photos]
* [http://rbg-web2.rbge.org.uk/bbs/Resources/Fletcher.pdf Moss grower's handbook (2.3 9MB PDF file)]
* [https://web.archive.org/web/20190531140115/http://britishbryologicalsociety.org.uk/ The British Bryological Society]
* [http://www.pflanzenliebe.de/innen/innen_moose/innen_moose.html Picture Gallery of Mosses]
* [http://worldofmosses.com World of Mosses – Watercolour paintings of moss by Robert Muma]

{{Plant classification}}
{{Bryophyta}}
{{Life on Earth}}
{{Taxonbar|from=Q25347}}
{{Authority control}}

[[Category:Mosses| ]]
[[Category:Extant Carboniferous first appearances]]
[[Category:Mississippian first appearances]]