BRYOPHYTESFEATURES, CLASSIFICATION & ECONOMIC IMPORTANCE

Course: B.SC. BotanySemester: II

Paper Code: BOT CC-204Paper Name: Archegoniate

Topic: BRYOPHYTES(General Account)Faculty Name: Dr.Anjana Verma

Department : BotanyEmail Id: anjana.nath.verma@gmail.com

• The division Bryophyta include over 2500 species

• Bryon= moss and phyton= plant

• Non-vascular embryophytes

• Small plants (2 to 60 cm)

• Terrestrial but require external water to complete their life-cycle

• They are called “Amphibians of the plant kingdom”

• Fossil record indicates they evolved on earth about 395-430million years ago

• Study of bryophytes – Bryology

• Father of bryology – Hedwig

• Father of Indian bryology – Shiv Ram Kashyap

FEATURES OF A TYPICAL BRYOPHYTE

• They grow in damp and shady places

• They have sharply defined heteromorphic alternation of generation

• Dominant plant body is gametophyte on which sporophyte is semiparasitic for nutrition

• The thallus( gametophyte) is differentiated in rhizoids, axis(stem) and leaves

• The thalli is multicellular but not differentiated, consists of parenchymatous cells

• They bear prominent chloroplasts with pyrenoids like Algae

• Moss have conducting tissues but not spacialized as xylem or phloem

• Usually multiply by means of vegetative mode of reproduction

• The gametophyte bears multi-cellular and jacketed sex organs

• Male gametophyte develops Antheridium which has antherozoids

• Female gametophyte develops Archegonium which has egg

• Sexual reproduction is oogamus type

• Multicellular embryo develops inside the archegonium

• Sporphyte is differentiated into foot, seta and capsule

• Capsule produces haploid meiospores/ spores of similar types (homosporous)

• Spore germinates into juvenile gametophyte called protonema

CLASSIFICATION

RESEMBLENCE OF BRYOPHYTES WITH ALGAE

ALGAE

• Mostly aquatic and green

• Filamentous , evolved group bears slight differentiation having multicellular thallus with distinct holdfast and sex organs.

• Plant body is thallus-like, green, autotrophic containing chlorophyll and reserve food as pyrenoids

• Cell wall is made up of cellulose

• Gametophyte is dominant

• Spermatozoids are biflagllate , both are whiplash type and motile

• Water is required for fertilization

BRYOPHYTES

• Mostly green, terrestrial but prefer damp and shady places and water is essential to complete their life cycle

• The plant body is thallus well differntiated into rhizoids axis and leaf. Chlorophyll and pyrenoids present

• Cell wall is made up of cellulose

• Gametophyte is dominant

• Antherozoids are bicilliate and motile

• Water is required for fertilization

• The protonema resembles with filamentous green algae.

RESEMBLANCE OF BRYOPHYTES WITH PTERIDOPHYTES

BRYOPHYTES

• Terrestrial

• Thallus is well differentiated in root like rhizoids, axis/stem and leaf

• Development of embryo after fertilization

• Androcytes are enclosed within a single layered jacket

• Antherozoids are biflagellate

• Archegonium is flask shaped in structure bearing egg protected by sterile cells

• Water is essential for fertilization

• Heteromorphic alternation of generation where gametophyticthallus is dominant, sporophyte is partially or totally dependent

• Vascular tissues are not well developed

PTERIDOPHYTES

• Terrestrial

• Primitive (Psilotum) can be compared with sporophyte of bryophytes

• Development of embryo after fertilization

• Androcytes are enclosed within a single layered jacket

• Antherozoids are biflagellate

• Archegonium is similar bearing egg protected by sterile cells

• Water is essential for fertilization

• Heteromorphic alteration of generation where sporophytic thallusis dominant and independent

• Vascular tissues are well developed

This genus comprises of 65 species

They are cosmopolitan. Some common species are M.palmata, M.polymorpha, M.indica, M.nepalensis

-The thalli grows on moist soil (best in burnt soil)

Thallus is prostrate, dichotomously branched and dorsiventrally differentiated.

Dorsal surface is deeper, bearing rhomboidal or polygonal small areas having pores in its centre.

The apex of each branch bears notch for growth

Thallus bears conspicuous mid-rib (groves) on the dorsal surface and ridge on the ventral surface bearing multicellular scales and colorless and unicellular rhizoids (smooth walled and tuberculate)

The sexually mature thalli bear specialized gametophores

Antheridiophore & Archegoniophore

T.S. of the thallus consists of upper and lower epidermis

It is well differentiaited into photosynthetic and storage zones. Uppermost cells are compactly arranged and contains chloroplasts while the lower cells are thin walled parenchymatous containing starch and oil body.

Dorsal surface bears Gemma cups having gemmae for vegetative reproduction.

MARCHANTIA (HEPATICOPSIDA)

ANTHOCEROS (ANTHCEROTOPSIDA)

Hornwort due to characteristic horn-shaped sporophytesGlobally present. Some common species are A.erecrus, A.himalayensis, A.chambnsis, A.punctatus, A.laevisSmall green thallus, lobed along the marginThe spores are dark grey, dark brown or blackSporophytes are larger and much more complex differentiated into foot, a constriction zone and capsule.Anthoceros are host to species of Nostoc (a symbiotic association)so the ventral surface shows blue-green patches The dorsal surface is smooth or rough with spines.Ventral surface bears many unicellular smooth walled rhizoidsT.S. shows uniform distribution of parenchymatous cells Each cell contains a single large discoid or oval chloroplastEach chloroplast encloses a single large conspicuous pyrenoidThe ventral surface bears cavities filled with mucilageThese cavities open on the ventral surface through slitsVegetative mode of reproduction is more common

SPHAGNUM (BRYOPSIDA)

Commonly known as bog moss or peat moss

Sphagnum is the largest genus of the sub-class Sphagnidae (380species) of class Bryopsida

Some common species are S.aciphyllum, S.imperforatum, S.capilifolium, S.exil.

They have distinct structure adapted to the watery habitat as water acts to support the plant.

Main body consists of a stem/axis and branches. Rhizoids are only present in developing plant.

Stem and branches are covered with photosynthesizing leaves.

They have two distinct cell types- normal photosynthesizing cells with chlorophyll

Additionally barrel shaped aline or retort cells having pores and soak up water like a sponge.

They are the most useful plant due to their water retaining and absorbing capacity.

Decayed dried sphagnum moss forms peat which is used as soil conditioner (increases water holding capacity). Dried moss is used as an insulating material.

FUNARIA (BRYOPSIDA)

Funaria is the common moss present in almost every part of the World

It is a genus of approximately 310 species

Common species are F.hygrometrica, F.apophysata, F.acutifolia, F.acidota

Moss plant grows in dense patches/cushions in moist shady and cool places

It has a height of 3-5 cm, a radial symmetry with differentiation of an axis/stem, leaves and multicellular, colorless branched rhizoids with oblique septa.

The plant body is green, soft and upright, main axis bears a set of spirally arranged sessile leaves having a clearly distinguishable mid-rib.

At the apex of the main axis the antheridium is borne in male plant.

A lateral branch from the main plant axis bears the female shoot archegonium.

In a mature plant the lower leaves are small, membranous called as

Scaly leaves, middle larger, green leaves called foliage leaves and

Uppermost compactly arranged perichaetial leaves.

ALTERNATION OF GENERATION

• Also known as metagenesis

• Haplodiplontic, Diplobiontic or Dibiontic

• They have distinct haploid (sexual) and diploid (asexual) phases

• Multicellular haploid gametophyte with n-chromosomes alternates with a multicellular diploid sporophytes with 2n chromosomes.

• The haploid spores germinate and grow into a haploid gametophyte.

• At maturity, the gametophyte produces gametes by mitosis.

• Two gametes (antherozoids and egg) fuse to produce a diploid zygote (2n).

• The zygote develops into diploid sporophyte.

• A mature sporophyte produces haploid spores by meiosis, a process which reduces the number of chromosomes to half (n).

• In Bryophytes the sporophyte is less well developed and is dependent on gametophyte for nutrition and shelter.

• Within Bryophytes the sporophyte gradually becomes complex, developed and partially independent as they start bearing green parenchymatous cells.

ECOLOGICAL IMPORTANCE

• Pioneer of land plants

• Bryophytes are pioneer of land plants because they are the first plant to grow and colonize the barren rocks and lands.

• Bryophytes are among the oldest land plants, Grosse-Brauckmann (1979) reported that there were indication of stone age uses of moss Neckera crispa(feather moss) by prehistorian men in a lakeshore settlement in West Germany.

• Soil erosion

• They prevent soil erosion because they usually grow densely and act as soil binders. Mosses grow in dense stands forming mat or carpet like structure thus bears the impact of falling rain drops. It also holds much of water and reduces run-off water.

• Formation of soil

• The acid secreted by the lichens and progressive death and decay of mosses help in the formation of soil.

• Bog succession

• Peat mosses change the banks of lakes or shallow water bodies into solid soil which supports vegetation (Sphagnum).

ECONOMIC USE

• Formation of Peat• Peat is brown or dark colored substance formed by the

gradual compression and carbonization of the partiallydecomposed pieces of dead vegetative matter in the bogs.Sphagnum is an aquatic moss. While growing in water it secretescertain acids in the water body. This acid makes conditionunfavorable for the growth of decomposing organisms like bacteriaand fungi. Absence of oxygen and decomposing microorganismslows down the decaying process of dead material and a largeamount of dead matters added year by year. It is called peat (dueto this Sphagnum is called as peat moss) which has various uses :

• Used as fuel in Ireland, Scotland and Northern Europe.• In production of various products like ethyl alcohol, ammonium

sulphate, tar, ammonia, paraffin, tannin materials, etc.• In horticulture to improve the soil texture.• In surgical dressings.

OTHER USES

• As packaging material• Dried mosses and bryophytes have great ability to hold water. Due to

this ability they are used as packing material for shipment of cut flowers, vegetables, perishable fruits, bulbs, tubers etc.

• As budding stocks• Because of great ability of holding and absorbing water, in nurseries

beds are covered with thalli of bryophytes.• In Experimental Botany• The liverworts and mosses play an important role as research tools

in various fields of Botany such as genetics. • As Food• Bryophytes are not directly used as human food. Landley (1956)

mentioned Sphagnum as a wretched food in barbarous countries.• Bryum and polytrichum constitute the chief diet of the Norwegian

grouse chicks.• Some bryophytes such as mosses are used as food by chicks, birds,

reindeer, etc.

MEDICINAL USES

• Some bryophytes are used medicinally in various diseases

• Pulmonary tuberculosis and affliction of liver—Marchantia app.

• Antiseptic properties and healing of wounds – Sphagnum leaves and extracts of some bryophytes shows anticeptic properties for ex—Concephalum, Dumortiera, S.protoricense, S.strictum.

• Hart well (1971) reported that extracts of Marchentia polymorpha, M.stellata and M. commune posses antitumour properties.

• The dried Sphagnum is boiled in water, the decoction is used in the treatment of acute Haemorhage and disease of Eye

• Tea made of Polytrichum commune helps to dissolve stones of kidney and gall bladder.