HOME

TheInfoList



OR:

Mosses are small, non-vascular
flower A flower, sometimes known as a bloom or blossom, is the reproduction, reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providin ...

flower
less
plant
plant
s in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''
sensu lato ''Sensu'' is a Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around prese ...
'', Schimp. 1879) may also refer to the parent group
bryophyte
bryophyte
s, 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
leaves
that are generally only one cell thick, attached to a
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. Mosses do not have
seed
seed
s and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing spores. They are typically tall, though some species are much larger. ''Dawsonia'', the tallest moss in the world, can grow to in height. There are approximately 12,000 species. Mosses are commonly confused with liverworts, hornworts and
lichen
lichen
s.Lichens of North America, Irwin M. Brodo, Sylvia Duran Sharnoff, , 2001 Mosses are grouped with the hornworts and liverworts as "non-vascular" plants in a division, all of them having the haploid gametophyte generation as the dominant phase of the life cycle (though in fact many mosses have advanced vascular systems). This contrasts with the pattern in all vascular plants ( seed plants and pteridophytes), where the
diploid Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Sets of chromosomes refer to the number of mat ...
sporophyte generation is dominant. Lichens may superficially resemble mosses, and sometimes have common names that include the word "moss" (e.g., "
reindeer moss ''Cladonia rangiferina'', also known as reindeer cup lichen, reindeer lichen (cf. Sw. Olof Peter Swartz (21 September 1760 – 19 September 1818) was a Swedish botanist and taxonomist. He is best known for his taxonomic work and studies in ...
" or "
Iceland moss ''Cetraria islandica'', also known as true Iceland lichen or Iceland moss, is an Arctic-alpine lichen whose erect or upright, leaflike habit gives it the appearance of a moss, where its name likely comes from. Description It is often of a pale ...
"), but they are not related to mosses. The main commercial significance of mosses is as the main constituent of
peat Peat (), also known as turf (), is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. The peatland ecosystem covers and ...
(mostly the genus ''
Sphagnum ''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, peat moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store wa ...
''), 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.


Physical characteristics


Description

Botanically, mosses are non-vascular plants in the land plant division Bryophyta. They are usually small (a few centimeters tall)
herbaceous Herbaceous plants are vascular plants that have no persistent wood, woody stems above ground. This broad category of plants includes many perennial plant, perennials, and nearly all Annual plant, annuals and Biennial plant, biennials. Definition ...
(non-woody) plants that absorb water and nutrients mainly through their leaves and harvest
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon Carbon () is a chemical element with the chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetraval ...
and sunlight to create food by
photosynthesis Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemica ...
. With the exception of the ancient group
Takakiopsida ''Takakia'' is a genus of two species of mosses known from western North America and central and eastern Asia. The genus is placed as a separate Family (biology), family, Order (biology), order and Class (biology), class among the mosses. It has ...
, no known mosses form
mycorrhiza   A mycorrhiza (from Ancient Greek, Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, mycorrhiza or mycorrhizas) is a symbiosis, symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role ...
, but bryophilous fungi is widespread in moss and other bryophytes, where they live as saprotrophs, parasites, pathogens and mutualists, some of them endophytes. They differ from vascular plants in lacking water-bearing
xylem Xylem is one of the two types of transport tissue in vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of embryophyte, land plants ( accepted known species) that have lignin, ...
tracheids or vessels. As in liverworts and hornworts, the haploid gametophyte generation is the dominant phase of the life cycle. This contrasts with the pattern in all vascular plants ( seed plants and pteridophytes), where the
diploid Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Sets of chromosomes refer to the number of mat ...
sporophyte generation is dominant. Mosses reproduce using
spore In biology, a spore is a unit of sexual reproduction, sexual or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of ...
s, not s, and have no flowers. Moss gametophytes have stems which may be simple or branched and upright or prostrate. The early divergent classes Takakiopsida, Sphagnopsida, Andreaeopsida and Andreaeobryopsida either lack
stoma In botany, a stoma (from Greek language, Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. ...
ta or have pseudostomata that do not form pores. In the remaining classes, stomata has 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. They do not have proper
root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often b ...
s, but have threadlike rhizoids that anchor them to their substrate. Mosses do not absorb water or nutrients from their substrate through their rhizoids. They can be distinguished from liverworts (
Marchantiophyta The Marchantiophyta () are a division of non-vascular plant, non-vascular embryophyte, land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the pla ...
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 the polysporangiophytes, which include all vascular plants. The spore-bearing sporophytes (i.e. the
diploid Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Sets of chromosomes refer to the number of mat ...
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 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.


Life cycle

Vascular s have two sets of
chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
s in their vegetative cells and are said to be
diploid Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Sets of chromosomes refer to the number of mat ...
, i.e. each chromosome has a partner that contains the same, or similar, genetic information. By contrast, mosses and other 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. The moss life-cycle starts with a haploid
spore In biology, a spore is a unit of sexual reproduction, sexual or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of ...
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 An archegonium (pl: archegonia), from the ancient Greek ''ἀρχή'' ("beginning") and ''γόνος'' ("offspring"), is a multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female gam ...
) 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 An antheridium is a haploid structure or organ producing and containing male gametes (called ''antherozoids'' or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. Androecium is also t ...
) 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 is disrupted by fungal
chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or material consisting of very large molecules called macromolecules, ...
. Galotto ''et al.'', 2020 apply chitooctaose and find that tips detect and respond to this chitin derivative by changing
gene expression Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. T ...
. They find this defense response is probably conserved from the most recent common ancestor of s and tracheophytes. Orr ''et al.'', 2020 find that the
microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nanometer, nm and have an inner diameter bet ...
s of growing tip cells are structurally similar to F-actin and serve a similar purpose. Mosses can be either
dioicous Dioicy () is a sexual system where Archegonium, archegonia and Antheridium, antheridia are produced on separate Gametophyte, gametophytes. It is one of the two main sexual systems in Bryophyte, bryophytes. Both dioicous () and Monoicy, monoicous ...
(compare
dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in Spermatophyte, seed plants). Dioeci ...
in seed plants) or
monoicous Monoicy () is a sexual system in haploid plants (mainly bryophytes) where both sperm and eggs are produced on the same gametophyte, in contrast with dioicy, where each gametophyte produces only sperm or eggs but never both.Crandall-Stotler, B.J. ...
(compare
monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is conne ...
). 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 Fertilisation or fertilization (see American and British English spelling differences#-ise, -ize (-isation, -ization), spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give ...
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. After fertilisation, the immature sporophyte pushes its way out of the archegonial venter. It takes about a quarter to half a year 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 the capsule is mature. Within the capsule, spore-producing cells undergo
meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately ...
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 Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
Sphagnum ''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, peat moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store wa ...
'' the spores are projected about off 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 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 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 Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the ...
, and the genetically identical units can lead to the formation of clonal populations.


Dwarf males

Moss dwarf males (also known as nannandry or phyllodioicy) originate from wind-dispersed male
spore In biology, a spore is a unit of sexual reproduction, sexual or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of ...
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. 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 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 Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essenti ...
may be involved Having the males growing as dwarfs on the female is expected to increase the
fertilization Fertilisation or fertilization (see American and British English spelling differences#-ise, -ize (-isation, -ization), spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give ...
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 phyllodioicous species. Dwarf males occur in several unrelated lineages and is showing to be more common than previously thought. For example, it is estimated that between one quarter and half of all
dioicous Dioicy () is a sexual system where Archegonium, archegonia and Antheridium, antheridia are produced on separate Gametophyte, gametophytes. It is one of the two main sexual systems in Bryophyte, bryophytes. Both dioicous () and Monoicy, monoicous ...
pleurocarps have dwarf males.


DNA repair

The moss '' Physcomitrella patens'' has been used as a
model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biology, biological phenomena, with the expectation that discoveries made in the model organism will provide insight into th ...
to study how plants repair damage to their DNA, especially the repair mechanism known as
homologous recombination Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in Cell (biology), cellular organi ...
. If the plant cannot repair DNA damage, e.g.,
double-strand breaks DNA repair is a collection of processes by which a cell (biology), cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolism, metabolic activities and environmental factors such as r ...
, in their
somatic cell A somatic cell (from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following peri ...
s, the cells can lose normal functions or die. If this occurs during
meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately ...
(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 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, 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.


Classification

More recently, mosses have been grouped with the liverworts and hornworts in the division Bryophyta (s, or Bryophyta ''sensu lato''). The bryophyte division itself contains three (former) divisions: Bryophyta (mosses),
Marchantiophyta The Marchantiophyta () are a division of non-vascular plant, non-vascular embryophyte, land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the pla ...
(liverworts) and
Anthocerotophyta Hornworts are a group of Non-vascular plant, non-vascular Embryophytes (land plants) constituting the division Anthocerotophyta (). The common name refers to the elongated horn-like structure, which is the sporophyte. As in mosses and liverworts, ...
(hornworts); it has been proposed that these latter divisions are de-ranked to 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: 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 ''Ambuchanania leucobryoides'' is the only species in the monotypic In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, cohe ...
'' and ''
Sphagnum ''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, peat moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store wa ...
'', 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 high. The tallest land moss, a member of the Polytrichidae is probably '' Dawsonia superba'', a native to
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 List of islands of New Zealand, smaller islands. It is the ...
and other parts of
Australasia Australasia is a region that comprises Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. ...
.


Geological history

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 The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...
of Antarctica and Russia, and a case has been made for
Carboniferous The Carboniferous ( ) is a Period (geology), geologic period and System (stratigraphy), system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago (Myr, Mya), to the beginning of the Permian Period, ...
mosses. It has further been claimed that tube-like fossils from the
Silurian The Silurian ( ) is a period (geology), geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (annum, Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortes ...
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 The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya ...
ice ages occurred. When the ancestors of today's moss started to spread on land 470 million years ago, they absorbed CO2 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 CO2 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 CO2 dropped all over the world, allowing the formation of ice caps on the poles.


Ecology


Habitat

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 Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
flow, in
Iceland Iceland ( is, Ísland; ) is a Nordic countries, Nordic island country in the Atlantic Ocean, North Atlantic Ocean and in the Arctic Ocean. Iceland is the most list of countries and dependencies by population density, sparsely populated coun ...
File:Moss (Iceland) 03.jpg, Moss growing along seeps and springs in newly deposited
basaltic Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
rock, Iceland. File:Steinerne Rinne bei Obererasbach im Altmühltal.jpg, Moss growing along the stream from a karst spring;
travertine Travertine ( ) is a form of terrestrial limestone deposited around mineral springs, especially hot springs. It often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and even rusty varieties. It is formed by a pro ...
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 sporophytes 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 Retaining walls are relatively rigid walls used for supporting soil laterally so that it can be retained at different levels on the two sides. Retaining walls are structures designed to restrain soil to a slope that it would not naturally keep to ...
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
Since moss gametophytes are
autotroph An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Works", ...
ic they require enough
sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible spectrum, visible, and ultraviolet light. On Earth, sunlight is light scattering by particles, scattered and attenuation, filtered t ...
to perform
photosynthesis Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemica ...
. 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 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
humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Latin ...
y soil, downed logs, burnt stumps, tree trunk bases, upper tree trunks, and tree branches or in
bog A bog or bogland is a wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) ...
s. Moss species growing on or under trees are often specific about the species of trees they grow on, such as preferring conifers over broadleaf trees,
oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
s over
alder Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the Temperate climate, north temperate z ...
s, or vice versa. While mosses often grow on trees as
epiphytes An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called Phorophy ...
, 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. Such aquatic or semi-aquatic mosses can greatly exceed the normal range of lengths seen in terrestrial mosses. Individual plants 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 the year to complete fertilisation. Many mosses can survive
desiccation Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container ...
, sometimes for months, returning to life within a few hours of rehydration. It is generally believed that in the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North ...
, 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 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 In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
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.


Relationship with cyanobacteria

In boreal forests, some species of moss play an important role in providing nitrogen for the ecosystem due to their relationship with nitrogen-fixing
cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum (biology), phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's ...
. 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.


Cultivation

Moss is often considered a
weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by
Japanese garden are traditional gardens whose designs are accompanied by Japanese aesthetics and philosophical ideas, avoid artificial ornamentation, and highlight the natural landscape. Plants and worn, aged materials are generally used by Japanese garden desig ...
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 Bonsai ( ja, 盆栽, , tray planting, ) is the Japanese art of growing and training miniature trees in pots, developed from the traditional Chinese art form of ''penjing''. Unlike ''penjing'', which utilizes traditional techniques to produce ...
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 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 A brick is a type of block used to build walls, pavements and other elements in masonry construction. Properly, the term ''brick'' denotes a block composed of dried clay, but is now also used informally to denote other chemically cured cons ...
,
wood Wood is a porous and fibrous structural tissue found in the Plant stem, stems and roots of trees and other woody plants. It is an organic materiala natural composite material, composite of cellulose fibers that are strong in tension and emb ...
, and certain coarse concrete mixtures, are hospitable to moss. Surfaces can also be prepared with acidic substances, including
buttermilk Buttermilk is a Fermented milk products, fermented dairy drink. Traditionally, it was the liquid left behind after churning butter out of Microbial food cultures, cultured cream. As most modern butter in western countries is not made with cul ...
,
yogurt Yogurt (; , from tr, yoğurt, also spelled yoghurt, yogourt or yoghourt) is a food produced by bacterial Fermentation (food), fermentation of milk. The bacteria used to make yogurt are known as ''yogurt cultures''. Fermentation of sugars in t ...
,
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...
, and gently puréed mixtures of moss samples, water and ericaceous compost. In the cool, humid, cloudy
Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...
, moss is sometimes allowed to grow naturally as a
moss lawn Moss lawns are lawns composed of moss, which occur naturally, but can also be cultivated like grass lawns (see Moss lawn#Gallery, images). They are a defining element in moss gardens. Moss lawns are drought-tolerant and rarely need misting once ...
, 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, 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.


Green roofs and walls

Mosses are sometimes used in
green roof A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a Waterproofing#Construction waterproofing, waterproofing membrane. It may also include additional la ...
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. Mosses are also used on green walls.


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. They grow more slowly than many aquarium plants, and are fairly hardy.


Growth inhibition

Moss can be a troublesome weed in containerized nursery operations and greenhouses. 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 Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
through
drainage Drainage is the natural or artificial removal of a surface's water and groundwater, sub-surface water from an area with excess of water. The internal drainage of most agricultural soils is good enough to prevent severe Waterlogging (agricult ...
. * Increasing direct sunlight. * Increasing number and resources available for competitive plants like
grass Poaceae () or Gramineae () is a large and nearly ubiquitous Family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species culti ...
es. * Increasing the
soil pH Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the nega ...
with the application of 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 A fertilizer (American English) or fertiliser (British English; American and British English spelling differences#-ise, -ize (-isation, -ization), see spelling differences) is any material of natural or synthetic origin that is applied to soil ...
s.
Sulfur Sulfur (or sulphur in British English British English (BrE, en-GB, or BE) is, according to Oxford Dictionaries, " English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the ...
and
iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundance ...
are
essential nutrient A nutrient is a Chemical substance, substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungus, fungi, and protists. Nutrients can be incorporated into cells for me ...
s for some competing plants like grasses. Killing moss will not prevent regrowth unless conditions favorable to their growth are changed.


Uses


Traditional

Preindustrial societies made use of the mosses growing in their areas. Laplanders, North American tribes, and other circumpolar people used mosses for bedding. 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 cabins, and tribes of the northeastern United States and southeastern Canada used moss to fill chinks in wooden longhouses. Circumpolar and alpine peoples have used mosses for insulation in boots and mittens. Ötzi the Iceman had moss-packed boots. 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. 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. 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. In Finland, peat mosses have been used to make bread during famines.


Commercial

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 Peat (), also known as turf (), is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. The peatland ecosystem covers and ...
, 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 ''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, peat moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store wa ...
'' 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.The Plant Underworld, Sphagnum and Water, Australian Botanic Garden
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. It is also claimed to have antibacterial properties. Indigenous peoples of the Americas, Native Americans were one of the peoples to use ''Sphagnum'' for diapers and napkins, which is still done in Canada. 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, the approximate meaning of which is "against fire". In Mexico, moss is used as a Christmas in Mexico, Christmas decoration. '' Physcomitrella patens'' is increasingly used in biotechnology. Prominent examples are the identification of moss genes with implications for crop improvement or human health and the safe production of complex biopharmaceuticals in the moss bioreactor, developed by Ralf Reski and his co-workers. 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.


References


Further reading

Robin Wall Kimmerer, Kimmerer, Robin Wall (2003). ''Gathering Moss: A Natural and Cultural History of Mosses''. Oregon State University Press. ISBN (identifier), ISBN Special:BookSources/0-87071-499-6, 0-87071-499-6.


External links


Information, diagrams and photos

Moss grower's handbook (2.3 9MB PDF file)

The British Bryological Society



World of Mosses – Watercolour paintings of moss by Robert Muma
{{Authority control Mosses, Extant Carboniferous first appearances Mississippian first appearances