AskDefine | Define mosses

User Contributed Dictionary



  • /ˈmɑsəs/


  1. Plural of moss

Usage notes

The plural form mosses is used when more than one kind of moss is meant. The plural is moss when referring to a collection of moss plants of the same kind.

Extensive Definition

There are approximately 12,000 species of moss classified in the Bryophyta. The division Bryophyta formerly included not only mosses, but also liverworts and hornworts. These other two groups of bryophytes now are often placed in their own divisions.

Physical characteristics


Botanically, mosses are bryophytes, or non-vascular plants. They can be distinguished from the apparently similar liverworts (Marchantiophyta or Hepaticae) by their multi-cellular rhizoids. Other differences are not universal for all mosses and all liverworts, but the presence of clearly differentiated "stem" and "leaves", the lack of deeply lobed or segmented leaves, and the absence of leaves arranged in three ranks, all point to the plant being a moss.
In addition to lacking a vascular system, mosses have a gametophyte-dominant life cycle, i.e. the plant's cells are haploid for most of its life cycle. Sporophytes (i.e. the diploid body) are short-lived and dependent on the gametophyte. This is in contrast to the pattern exhibited by most "higher" plants and by most animals. In seed plants, for example, the haploid generation is represented by the pollen and the ovule, whilst the diploid generation is the familiar flowering plant.

Life cycle

Most kinds of plants have a double portion of chromosomes in their cells (diploid, i.e. each chromosome exists with a partner that contains the same genetic information) whilst mosses (and other bryophytes) have only a single set of chromosomes (haploid, i.e. each chromosome exists in a unique copy within the cell). There are periods in the moss lifecycle when they do have a full, paired set of chromosomes but this is only during the sporophyte stage.
The life of a moss starts from a haploid spore, which germinates to produce a protonema, which is either a mass of filaments or thalloid (flat and thallus-like). This is a transitory stage in the life of a moss. From the protonema grows the gametophore ("gamete-bearer") that is differentiated into stems and leaves ('microphylls'). From the tips of 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 have necks called venters which the male sperm swim down. The male organs are known as antheridia (singular antheridium) and are enclosed by modified leaves called the perigonium (plural, perigonia).
Mosses can be either dioicous (compare dioecious in seed plants) or monoicous (compare monoecious). In dioicous mosses, both male and female sex organs are borne on different gametophyte plants. In monoicous (also called autoicous) mosses, they 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 flagella that aid in propulsion. Since the sperm must swim to the archegonium, fertilisation cannot occur without water. 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 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.


Mosses were traditionally grouped with the liverworts and hornworts in the Division Bryophyta (bryophytes), within which the mosses made up the class Musci. This group, however, is paraphyletic and now tends to be split up. In such a system, the Division Bryophyta refers specifically to mosses. They appear to be the closest living relatives of the vascular plants.
The mosses are grouped as a single division, now named Bryophyta, and divided into six classes:
Polytrichopsida have leaves with lamellae, which are flaps on the leaves that look like the fins on a heat sink. These help it retain moisture. They differ from other mosses in other details of their development and anatomy too, and can also become larger than most other mosses, with e.g. Polytrichum commune forming cushions up to 40 cm (16 in) high. The tallest land moss, a member of the Polytrichidae is supposed to be Dawsonia superba, a native to New Zealand and Australia.
The Bryopsida are the most diverse group; over 95% of moss species belong to this class.
The Archidiidae are distinguished by their extremely large spores and the way the sporangium develops.

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 of Antarctica and Russia, and a case is put forwards for Carboniferous mosses. It has further been claimed that tube-like fossils from the Silurian are the macerated remains of moss calyptræ.


Mosses are found chiefly in areas of dampness and low light. Mosses are common in wooded areas and at the edges of streams. Mosses are also found in cracks between paving stones in damp city streets. Some types have adapted to urban conditions and are found only in cities. A few species are wholly aquatic, such as Fontinalis antipyretica, and others such as Sphagnum inhabit bogs, marshes and very slow-moving waterways. Such aquatic or semi-aquatic mosses can greatly exceed the normal range of lengths seen in terrestrial mosses. Individual plants 20–30 cm (8-12 in) or more long are common in Sphagnum species for example.
Wherever they occur, mosses require moisture to survive because of the small size and thinness of tissues, lack of cuticle (waxy covering to prevent water loss), and the need for liquid water to complete fertilisation. Some mosses can survive desiccation, returning to life within a few hours of rehydration.
In northern latitudes, the north side of trees and rocks will generally have more moss on average than other sides (though south-side outcroppings are not unknown). This is assumed to be because of the lack of sufficient water for reproduction on the sun-facing side of trees. South of the equator the reverse is true. In deep forests where sunlight does not penetrate, mosses grow equally well on all sides of the tree trunk.


Moss is considered a weed in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by Japanese gardening. In old temple gardens, moss can carpet a forest scene. Moss is thought to add a sense of calm, age, and stillness to a garden scene. Rules of cultivation are not widely established. Moss collections are quite often begun using samples transplanted from the wild in a water-retaining bag. However, specific species of moss can be extremely difficult to maintain away from their natural sites with their unique combinations of light, humidity, shelter from wind, etc.

Inhibiting moss growth

Moss growth can be inhibited by a number of methods:
  • Decreasing availability of water through drainage or direct application changes.
  • Increasing direct sunlight.
  • Increasing number and resources available for competitive plants like grasses.
  • Increasing the soil pH with the application of lime.
Heavy traffic or manually disturbing the moss bed with a rake will also inhibit 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 fertilizers. Sulfur and Iron are essential nutrients for some competing plants like grasses. Killing moss will not prevent regrowth unless conditions favorable to their growth are changed.



Commercial use

In World War II, Sphagnum mosses were used as first-aid dressings on soldiers' wounds, as these mosses are highly absorbent and have mild antibacterial properties. Some early people used it as a diaper due to its high absorbency.
In Mexico, Moss is used as a Christmas decoration.


mosses in Afrikaans: Mos
mosses in Arabic: حزازيات
mosses in Bulgarian: Bryopsida
mosses in Catalan: Molsa
mosses in Czech: Mechy
mosses in Welsh: Mwsogl
mosses in Danish: Mosser
mosses in German: Laubmoose
mosses in Estonian: Lehtsammaltaimed
mosses in Esperanto: Muskoj
mosses in Spanish: Musgo
mosses in Finnish: Lehtisammalet
mosses in French: Bryophyta
mosses in Hungarian: Lombosmohák
mosses in Indonesian: Tumbuhan lumut
mosses in Italian: Bryophyta
mosses in Japanese: 蘚類
mosses in Lithuanian: Lapsamanės
mosses in Macedonian: Мов
mosses in Dutch: Mossen
mosses in Norwegian: Bladmoser
mosses in Polish: Mchy
mosses in Portuguese: Musgos
mosses in Russian: Мох
mosses in Simple English: Moss
mosses in Slovak: Machy
mosses in Serbian: Маховине
mosses in Swedish: Bladmossor
mosses in Turkish: Yapraklı karayosunları
mosses in Ukrainian: Мохи
mosses in Walloon: Mossirea
mosses in Chinese: 苔蘚植物門
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