INTRODUCTION

Bryophytes are called as ‘Amphibians of the plant kingdom’ because
of their moist and aquatic habitat. Bryophyte is acquired from Greek word which
interprets that plants which inflates by absorption of water (Vanderpooten
& Goffinet, 2009). ). About 15 000 species of mosses are
known world-wide (Richardson, 1981), most of which are abundantly distributed
amongst the different ecosystems, growing on a variety of substrates Bryophytes are the diverse and distinct group of primitive
plants, with about 25,000 species distributed over the world, making the second
largest group of land plants. Bryophytes are non-flowering plants and are also
known as cryptogams. The species are worldwide distributed i.e. in tropical, sub-tropical,
alpine, sub alpine regions. These plants are considered as distinctive division
of non-vascular plants and got the position between algae and pteridophytes. (Matsuo & Sato, 1991). They range in size from few millimeters to centimeters. The life
cycle of bryophytes completes in two well defined generations called as
gametophytic and sporophytic generation. In bryophytes life gametophytic
generation dominates the sporophytic generation. Sporophyte of the palnts is
totally dependent on the gametophyte throughout their life; it obtain their
nutrient, minerals, food from gametophyte. Gametophyte is mostly green in color
and anchored in the soil by means of root like structure called rhizoids, while
sporophyte consists of foot, seta and capsule. The gametophytes have no stomata.(Schofield,
1982; Vanderpooten & Goffinet, 2009).The group
includes three distinct lineages viz. liverworts, hornworts and mosses.

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1.1 Habitat

In nature bryophytes are distributed neither uniformly nor
abundantly. As a
rule they are habitat specific mostly found in moist habitat. Mosses such as
Bryum, Pohlia, Ceratodon and some polytrichum species can be colonized in any
open ,suitably moist environment. Since bryophytes are non-vascular plants and
do not have any advanced system for transport of water and they cannot stop
evaporation from tissues. Bryophyte are autotrophs as they are photosynthetic
in nature. They are found on different substrates as depending on the nature of
species, i.e. rocks, tree trunk, mineral soil, acid soil, calcareous stone,
silicone stone, waterfalls spray areas, humus soil; stream sides, and downed
logs. Bryophytes are also epiphytic in nature and can
not live as parasite,. (Vanderpooten & Goffinet, 2009).

 

 

1.2 Systematic positions
in the plant kingdom

Many scientists classified plants periodically and suggested different
types of classifications. Prior system of classification was artificial system
of classification which was established on visible characters. Carolus Linnaeus
(1953) was the first who classified the plants into 24 major classes based on
single character i.e. number and arrangement of stamens. He  grouped all non-flowering plants in
Cryptogamia and plants having stamens into Phenarogams (Naikae, 2000).

After that Plant kingdom were divided by Endlicher (1836) into two
main divisions’ i.e. Thallophyta and
Cormophyta. The name Cormophyta
was given due to the definite solid ‘Cormus’ – type of plant body. Engler
(1886) suggested that the plant kingdom should be divided into two groups Thallophyta where embryo is not formed and
Embryophyta where zygote is
develops into multicellular embryo.

Eichler (1880, 1883) proposed another phylogenetic system of
classification and divided the plant kingdom into two main groups i.e. Cryptogamae or Cryptogamia (Cryptogams
– non-flowering plants) and Phanerogamae
or Phanerogamia (Phanorogams – flowering plants).

 Cryptogams (Greek word-
Kryptos = concealed or hidden, gamos = marriage). Phanorogams (Phaneros =
evident, gamos = marriage).

The cryptogamic plant was further divided into three main
divisions: Thallophyta, Bryophyta and
Pteridophyta while Phanerogamic
divided into two main divisions: Angiosperms
(covered ovule or seed),
Gymnosperms (naked ovule or seed).

Adolf Engler published his book
‘syllabus der Pflanzenfamilien’ in 1892 in which he classified plant kingdom
into two divisions Thallophyta and Embryophyta. The Embryophyta was divided
into two major groups (1) Embryophyta Asiphonogama (including Bryophyta and
Pteridophyta) and (2) Embryophyta siphonogama (Spermatophyta).

Bold (1956-1957) divide the plant the plant divided into two
divisions in (i) Hepaticophyta and (ii) Bryophyta. Takhtajan and Zimmerman
(1966) divided the plant kingdom into two division (i) Thallobionta
(Thallophytes) and (ii) Embryobionta (Cormophytes or Telomophytes) the latter
one with division of Rhyniophyta (Psilophytales) Bryophyta, Psilophyta and
other Tracheophytes.

In the current day of taxonomy, the terms – Cryptogamia
‘Phanerogamia’ and Archegoniatae are more or less obsolete now. However,
Bryophyta, Pteridophyta, Gymnosperms and Angiosperms still have their definite
entity.

 

1.3 Classification

Taxonomically bryophytes are classified between
algae and pteridophyytes; there are about 25000 species which are dispersed
over the world. These are further divided into three major classes,
Hepaticopsida, Anthocerotopsida and Bryopsida. Hepaticae (Liverworts, 6000
species) Anthocerotae (Hornworts, 300 species (Garnier et al., 1969; Suire,
1972; Ding, 1982; Wu, 1982) and mosses are the most leading group among
bryophytes which dwell 17,000 species having 3 sub class, 4 order, 89 families,
900 plus genera distributed worldwide (Richardson, 1981; Vitt, 1984). Mosses
are further divided into Acrocarp and Pleurocarp which are based on their
morphological analysis. Acrocarpous are those in
which sporophyte arise from terminal poition which in plerurocarpous sporophyte
arise from lateral position. (Dansereau; 1957 &
Ricklefs; 1990).

1.4 Vegetative Reproductions

 Bryophytes also
reproduce vegetatively when conditions are available for growth .mostly the
reproduce when a vegetative branch cut off from a parent plant and when it
require favourable conditions it grow into a new plant. Gemma cups are also
source of vegetative reproduction these are found on leaf margins or tips when
it separates from plant it convert into a new plant.(Kashyap, 1929). 

1.5 Sexual Reproduction

Bryophytes also do sexual reproduction and complete their life
cycle in two different phases I e gametophytic and sporophytic.In this
gametophytic generation is dominant over sporophytic generation.

1.6 Alternation of generation

Alternation
of generation in bryophytes was first time investigated by Hofmeister (1856).
He noticed that pteridophytes and bryophytes share some common characters .They
have multicellular gametangia, different alternation of generation, realization
of one large group, known as archegoniate. The archegoniate shows 2 well
developed and distinct generations i.e. (Gametophyte & Sporophyte) which
come after one another in sequence. Production of sexual organs occurs in sexual
reproduction. Spores are produce in sporophyte stage which having spore bearing
organs.

The number and position of chromosome was not known by scientist
till 1894.Straaburger was the first who sighted connection between gametophytic
and sporophytic generations by duplication and reduction of chromosomes.
Bryophytes show ploidy gametophytic having double set of chromosome while
sporophyte have single set of chromosome. Gametophytic phases occur between
meiosis to syngamy, while sporophyte phase occur
between syngamy to meiosis (Asthana et al., 2006).

1.6.1 Gametophyte      

Bryophytes form the natural group and main plant body is
gametophyte. It is totally independent and lasting and more visible and
prominent than sporophyte. Bryophytes are photosynthetic, the gametophyte is
usually small, well advance and mark off. The main plant body is in leafy forms
and having definite axis or leaf. There is a huge difference between stem and
leaves of bryophytes and vascular plants, in bryophytes these are part of gametophyte
while in vascular plants stem and leaves are part of sporophyte. it is part. In
Bryophytes, the stem and leaves are on central axial column and lateral
appendages. Plants attached firmly to the substratum by means of root like
structure called rhizoids these may be simple, pegged or tuberculate. Generally,
rhizoids are unicellular simple in Hornworts (smooth walled) simple and sinuate
in liverworts or multicellular in Mosses.

1.6.2 Antheridia

The reproductive organ of male plant is antheridia have a small or
large stalk and circular or spherical to elongated or clubed to cylindrical
antheridial body. The androgonial cells, androcytes and antherozoid mother
cells are cover or protected by a single layer of sterile jacket. Every
androcytes gives rise to a single ciliated motile antherozoid
(Asthana2006). 

1.6.3 Archegonia

The flask shaped and multicellular archegonia is female
reproductive organ. It consists of two parts venter and neck. The basal swollen
part is venter while upper elongated part is called as neck. The Venter
contains an egg and a venter canal cells. The gametes are produced in
multicellular organ which are surround by outer sterile jacket (Asthana 2006).

 

1.6.4 Fertilization

When antherozoids becomes mature the wall of antheridium splits up
and releases antherozoids these moves with the agency of water. Neck canal
cells disintegrate at the time of fertilization. The antherozoid move along
water into the venter of archegonia passes through the neck in venter
antherozooids fuses with egg and become fertilized. (Asthana 2006).

1.6.5 Embryo

Division start in fertilize egg immediately after the fertilization
of egg, without any resting stage and still they remain in archegonial wall.
Later on develop to multicellular embryos which change into sporophyte.
Archegonial Venter cells divide rapidly and form a protective layer around the
young sporophyte which is known as Calyptra
(Asthana2006).

1.6.6 Sporophyte

Sporophytes have three main parts foot, seta and capsule. Foot is
composed of parenchymatous tissues, narrowed structure, which remains embedded
in the gametophytic tissue and absorb food for the newly developing sporophyte.
Seta filament, like a stalk, which holds the capsule. Length of seta is
variable. The capsule is the fertile portion of the sporophytic generation. It
has uni to multi layered capsule wall enclosing archesporium. Archesporial
cells get differentiated into spore mother cells only in mosses or both the
spore mother cells and the elater mother cells in liverworts and hornworts. Spore
mother cells, after meiotic division, form spore tetrads having haploid spores.
The elater mother cells form elaters, which are sterile and help in the
dispersal of spores.  Size of spore is
same. Under favorable conditions, the spore germinates into new gametophyte
either directly (as in liverworts and hornworts) or a distinct phase intervenes
which is called as protonema (as in mosses).Later on buds arise from the
protonema to form new Plant (Asthana2006).

 

 

1.7 Economic Importance

Although there are at least estimation of bryophytes are 25000,
but there economical importance are unexplored except some species that have
shown importance.

1.7.1 Large Bio Mass

In tropical montane forests (for example, those in Los
Nevados, Colombia), the dry mass of epiphytic material in the higher canopy has
been recorded at above 100kg/m², or about 12% of the sum above-ground, dry tree
weight (Hofstede et al., 1993). total dry weight of epiphytes in these forests
was estimated at 44 tons/ha (90%being bryophytes). Bryophytes formed more of
the photosynthetically active (i.e., green) biomass in these forests than all
the other plant groups put together. It is significant to state that the
bryophyte mass in this type of forest is a main component of the total biomass and
is, therefore, an important component of the hydrological, chemical, and
organic matter cycles (Hofstede et al., 1993; Rhoades 1995).

1.7.2 Soil conservation and development

Mosses are often growing in dense or colonize form on,
bare rocks, and other abiotic surfaces. They bind soil and protect them from
erosion and destruction (Eldridge, 1993). In succession on mountains and rocks
bryophytes have the ability of formation of soil. In such habitat where the
lacks of nutrient, the bryophytes, lichens and soil becomes suitable for
herbaceous vegetation. Epiphytic humus accumulated by bryophytes can amount to
as much as 2.5 tons/ha of dry matter in elfin cloud forests of East Africa
(Pócs, 1980).

1.7.3 Peat Formation

Sphagnum is often the most important plant
in bogs and in the peat formation. Peat is undecided spongy plant material in
aquatic habitats. The vast and deep peat bogs in temperate and sub-Arctic zones
are estimated to cover 1% of the world’s surface (Clymo, 1970). Deposit 1.5
meters thick may have taken about 6,000 years to accumulate. Peats are used as
packing material and can be converted in making of flammable gases. These
disturbed peat lands then become sources rather than sinks for carbon in the
global ecosystem (Francez & Vasander, 1995).

 

 

1.7.4 Household Goods and Furnishings

The absorbent properties of
Sphagnum make it the most used moss of all the bryophytes.  It serves as an insulator, pillow, mattress,
and furniture stuffing, to keep milk warm or cool, to stuff into footmats to
clean shoes, to weave welcome mats, and in Lapland to line baby cradles,
keeping the infant clean, dry, and warm (R. M. Stark 1860).  The durability and elasticity of mosses may
well have contributed to Japanese stuffing balls and dolls with Hypnum (G. B.
Pant and S. D. Tewari 1990).

1.7.5 Clothing

In Germany, Sphagnum is
used to line hiking boots (L. Hedenäs 1991), where it absorbs moisture and
odor. Several cultures have used Sphagnum and Dicranum scoparium for lining
diapers.  Michigan’s Chippewa Indians
used Sphagnum for this purpose to keep babies clean and warm (H. A. Crum
1973).  Even modern diapers in the U.S.A.
and Canada can have Sphagnum liners (J. H. Bland 1971).  Today, the Johnson & Johnson Company uses
Sphagnum in diapers and sanitary napkins (L. M. Johnson Gottesfeld and D. H.
Vitt 1996).

1.7.6 Surgical

Early in the twentieth
century, several authors published accounts of the use of Sphagnum as a
surgical dressing (J. B. Porter 1917; J. W. Hotson 1918, 1919, 1921; G. E.
Nichols 1918, 1918b, 1918c, 1918d, 1920), saving precious cotton for use in
gunpowder during World War I. Sphagnum is superior to
cotton dressings in a number of ways (J. B. Porter 1917).  It absorbs three to four times as much liquid
at a rate about three times as fast, necessitating less frequent change.  It is also cooler, softer, less irritating,
retards bacterial growth (R. D. Banerjee 1974).

1.7.7 Anti-tumor Properties

Bryophytes subsequently
aroused the interest of the U.S. National Cancer Institute, where R. W. Spjut
et al. (1986) tested 184 species of mosses and 23 species of liverworts for
antitumor activity.  They found that
extracts of 43 species were active, while those of 75 species were toxic to the
test mice.  The most activity was found
in Brachytheciaceae, Dicranaceae, Grimmiaceae, Hypnaceae, Mniaceae,
Neckeraceae, Polytrichaceae, and Thuidiaceae. Several compounds from leafy liverworts exhibit antileukemic
activity (Y. Asakawa 1981).  Marchantin A
from Marchantia palacea, M. polymorpha, and M. tosana, riccardin from Riccardia
multifida, and perrottetin E from Radula perrottetii all show cytotoxicity
against the KB cells (Asakawa et al. 1982). 
Peat preparations hold some promise against some types of human cancer
(W. Adamek 1976).

1.7.8 Source of anti-biotic.

Recently chemical analyses show that some bryophytes are
used as source of antibiotics, including Sphagnum, Dumortia and Conocephalum  show positive anti microbial activity
(Banerjee, 1974). Recent tests on Riccia fluitans from Florida indicated no
ability to inhibit growth of bacteria (Pseudomonas aeruginosa, Staphylococcus
aureus) or yeast (Candida albicans) (A. L. Pates and G. C. Madsen 1955), and it
is unlikely tExtracts of some species of bryophytes contain some chemicals that
contain antimicrobial activity like phenolic and other compounds that stop
growth of bacteria and pathogenic fungi.

1.7.9 Medicines

The Doctrine of Signatures (where
medicinal employment of plants is suggested by their shape) has played a major
role in the use of bryophytes, especially liverworts, in herbal medicine.  For example, because Polytrichum commune has
long hairs on its calyptra, covering the capsule, the ladies in the time of
Dillenius used an oil extract from the calyptra to strengthen and beautify
their hair (J. J. Dillenius 1741; J. H. Bland 1971; H. A. Crum 1973).
Marchantia polymorpha to treat liver ailments; the surface suggests a cross
section of liver (H. Miller and N. G. Miller 1979); it reputedly will cool and cleanse the liver, remove yellow
jaundice, and remove inflammation (J. H. Bland 1971).

1.7.10 Pollution indicators

Bryophytes do not possess any layer for defense; they
are very sensitive to pollutants in the disturb environment. Taoda (1972) first
demonstrated that few bryophyte act as sign of pollution in Japan, Europe and
bryophytes have been used for controlling air pollution in Europe (Greven,
1992) and N America (Rao, 1982). Many species have been
used in various parts of the world as indicators and monitors of air pollution
because they satisfy the basic criteria of (i) readily accumulating airborne
pollutants, (ii) containing levels of pollutants in their tissues which vary as
a function of the distance from the source, (iii) having natural levels of
pollutant substances being fairly constant in the plants, and (iv) being
sensitive in their morphology to significant changes in pollution levels
(Laaksovirta and Olkaoknen, 1977).  Bryophytes are
used for monitoring atmospheric pollution indicator.Sphagnum and few species
are act as purifier of air.

Pottiaceae

The name pottiaceae was
first time used by Bruch  et al, (1834) in the book “Bryologia
Europaea” (1836-1850).It is also known as ‘mosses of the harsh environment’ Pottiaceae
is a very large family widely distributed in temperate regions of the world,
with a small number of species and genera occurring in tropical and arctic
regions. Most species of the Pottiaceae occur on calcareous habitats,
especially on rocks and disturbed soil. The family includes 7 subfamilies, 6
tribes, 76 genera, and some 2000 taxa worldwide (Zander 1993). Plants range in
size from small to medium or even large matt like or grow in clusters and
patches they cover large surface area green dorsally while brown ventrally. Stem
0.2-4 (10)cm, erect, short to elongate ,simple to compound branching, it has
well developed central strand sometimes may be absent. Stem leaves usually
pressed and often twisted when dry, unfurl when wet,they vary in shape from
oval to lanceolate or ligulate, elliptic .Leaf apices may be acute to obtuse, margins
entire to toothed. Costa sometimes present or absent if present then it may be
percurrent, excurrent or decurrent. Leaf cells may be unistratoe or bistratose.
Perichaetial leaves mostly present at base. Seta generally erect elongate
sometimes twisted mostly reddish to brown in colour. Capsules commonly erect
ovoid to cylindrical, neck usually absent,operculum may be short apiculate or
rostrate and calyptra present usually cucullate rarely mitarte. Peristome
usually single consisting of 16 teeth, they may be erect, oblique or often
spirally twisted teeth,sometimes absent or rudimentary .Spores usually 10-15?m or much larger.Plants do reproduce both sexually
and asexually. Specialized asexual reproduction is common by multicellular
gemmae which may borne on stalk or more seldom on leaves ,or by brood bodies
borne on rhizoids in the soil sometimes by fragile leaves or stems.Sexual
reproduction may be diocious or monocious ,rarely rhizautoicous; perigonial and
perichaetial leaves present may be terminal or lateral. Perigoniate plants usually
smaller than pericheatiate,Periheatal leaves mostly present on stem base
sheathing base.leaves may be linear,lancealate to long oval.