The individual plants are usually composed of simple leaves that are generally only one cell thick, attached to a stem that may be branched or unbranched and has only a limited role in conducting water and nutrients.

[6] Mosses do not have seeds and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing spores.

They are usually small (a few centimeters tall) herbaceous (non-woody) plants that absorb water and nutrients mainly through their leaves and harvest carbon dioxide and sunlight to create food by photosynthesis.

The early divergent classes Takakiopsida, Sphagnopsida, Andreaeopsida and Andreaeobryopsida either lack stomata or have pseudostomata that do not form pores.

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-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.

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.

The archegonia are small flask-shaped clumps of cells with an open neck (venter) down which the male sperm swim.

[20][21][22] Galotto et al., 2020 applied chitooctaose and found that tips detected and responded to this chitin derivative by changing gene expression.

In the presence of water, sperm from the antheridia swim to the archegonia and fertilisation occurs, leading to the production of a diploid sporophyte.

Flies attracted to the moss carry its spores to fresh herbivore dung, which is the favoured habitat of the species of this genus.

[27] 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.

[35] 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.

Aside from this character, the unique branching, thallose (flat and expanded) protonema, and explosively rupturing sporangium place it apart from other mosses.

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.

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.

[54] Mosses can live on substrates heated by geothermal activity to temperatures exceeding 50 degrees Celsius,[55] on walls and pavement in urban areas,[56] and in Antarctica.

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.

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.

In cool, humid, cloudy climates, all sides of tree trunks and rocks may be equally moist enough for moss growth.

[63] 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.

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.

[64] Moss is often considered a weed in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by Japanese gardening.

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.

Surfaces can also be prepared with acidic substances, including buttermilk, yogurt, urine, and gently puréed mixtures of moss samples, water and ericaceous compost.

Advantages of mosses over higher plants in green roofs include reduced weight loads, increased water absorption, no fertilizer requirements, and high drought tolerance.

With proper species selection for the local climate, mosses in green roofs require no irrigation once established and are low maintenance.

The mossery is typically constructed out of slatted wood, with a flat roof, open to the north side (maintaining shade).

[59] 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.

Decaying moss in the genus Sphagnum is also the major component of peat, which is "mined" for use as a fuel, as a horticultural soil additive, and in smoking malt in the production of Scotch whisky.