Dictionary of Meaning
<<Back
Please select a letter:
A |
B |
C |
D |
E |
F |
G |
H |
I |
J |
K |
L |
M |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
W |
X |
Y |
Z |
0-9
Click here for Shopping
MOSS
*** Shopping-Tip: MOSS
:This is an article about the plant. For other uses, see
Moss (disambiguation)''
{{Taxobox
| color = lightgreen
| name = Moss
| image = Haeckel Muscinae.jpg
| image_width = 240px
| image_caption = "Muscinae" from
Ernst Haeckel's ''Artforms of Nature'', 1904
| regnum =
Plantae
| divisio = '''Bryophyta'''
| classis = '''Bryopsida'''
| subdivision_ranks = Subclasses
| subdivision =
*
Sphagnidae
*
Andreaeidae
*
Tetraphidae
*
Polytrichidae
*
Archidiidae
*
Buxbaumiidae
*
Bryidae
}}
Image:Moss plants & Sporangium.jpg thumb|let|240px|Moss gametophyte generation plants with a single sporophyte.
'''Mosses''' are small
plants that are rarely taller than 2 inches (50 mm). They typically grow close together in clumps or mats in damp or shady locations. They do not have
flowers and their simple leaves cover the thin wiry stems. At certain times mosses produces
spore capsules which may appear as beak-like capsules borne aloft on thin stalks.
Overview
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.
The
Division (biology) 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.
Aside from lacking a
Vascular plants vascular system, they have a gametophyte-dominant
biological life cycle 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
vascular 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.
Image:Moss life Cycle.jpg thumb|left|300px|Life cycle of a typical Moss(Polytrichum commune)
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 (singular 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 with
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. Without water, fertilisation cannot occur. After fertilization, 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 (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.
In some mosses, 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.
Classification of mosses
Image:Three mosses and a tree.jpg thumb|240px|right|Three different types of mosses surround this tree trunk.
Image:Ant on mosshill02.jpg thumb|240px|right|Ant on mosshill
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 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 class, now named Bryopsida, and divided into seven subclasses:
*
Andreaeidae
*
Sphagnidae
*
Tetraphidae
*
Polytrichidae
*
Buxbaumiidae
*
Bryidae
*
Archidiidae
Andreaeidae 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.
The Sphagnidae, the peat-mosses, comprise the single genus ''
Sphagnum''. These 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.
The Tetraphidae are unique as their name implies, in having only four large peristome teeth surrounding the opening of the capsule.
Polytrichidae 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.
The Buxbaumiidae are called 'bug mosses' because they usually have a very small and reduced gametophore and the whole plant is mostly the sporophyte capsule. The shape reminds one of a bug, which is the reason for its common name.
Most (>95%) mosses belong to the Bryidae.
The Archidiidae are distinguished by their extremely large spores and the way the sporangium develops.
Habitat
Image:Moss in growth rings.jpg thumb|240px|Moss growing in the shelter of the growth rings of a stump
Image:Moss.jpg thumb|240px|Moss on a rock
Image:Mech plonnik mlode sporofity.jpg thumb|240px|Young sporophyte of the common hair cap moss (''Polytrichum commune'')
Mosses are found chiefly in areas of low light and dampness; any area of the world. Mosses are common in wooded areas and at the edges of streams. A few species are wholly aquatic, such as ''Fontinalis antipyretica'', and others such as ''Sphagnum spp'' inhabit bogs, marshes and very slow moving waterways. Such aquatic or semi aquatic mosses can greatly exceed the normal range of lengths seen in terestial mosses. Individuals plants many inches long are common in ''Sphagnum'' species for example. 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.
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 generally will have more moss on average than other sides. 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 sun-light does not penetrate, mosses grow equally well on all sides of the tree trunk.
Cultivation
Moss is considered a weed in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by
Japanese garden 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 site (with its unique combination of light, humidity, shelter from wind, etc).
Growing moss from spore 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 colonized 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 pureed mixtures of moss samples, water and
ericaceous compost.
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.
Commercial use of Mosses
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" both as a soil additive and for use in smoking
malt in the production of
Scotch whisky. There are growing concerns in parts of the world where this trade is growing, that significant environmental damage may be caused by the activities of commercial moss harvesters. In WW2, moss was used as a sort of a bandaid on soldiers wounds and some early people used it as a diaper due to its high absorbancy.
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.
See also
*
Embryophyte
*
Bryophyte
*
Lichen
External links
-
Information, diagrams and photos
-
Moss description
Category:Bryophyta
Category:Flora of Antarctica
bg:Мъхове
cy:Mwsogl
da:Mosser
de:Laubmoose
eo:Muskoj
fi:Lehtisammalet
fr:Bryophyta
id:Tumbuhan lumut
it:Muschio
ja:蘚類
lt:LapsamanÄ—
mk:Мов
no:Bladmoser
pl:Mchy
pt:Musgos
simple:Mosses
sr:Маховине
ru:Мох (раÑ?тение)
sv:Mossor
wa:Mossirea
'''MOSS''' can refer to:
*the
Mobile submarine simulator, a sonar decoy
*the
Market Oriented Sector Selective talks, trade negotiations held between the United States and Japan
{{4LA}}
*** Shopping-Tip: MOSS
