Kareena lohia: BRYOPHYTES AND PTERDOPHYTES FULL INFORMATIVE NOTES

BRYOPHYTES

Bryophytes include the various mosses and liverwort that are found commonly growing in moist shaded areas in the hills.

Bryophytes are also called amphibians of the plant kingdom because these plants can live in soil but are dependent on water for sexual reproduction.
They usually occur in damp, humid and shaded localities.
They play an important role in plant succession on bare rock /soil.
The plant body of bryophytes is more differentiated than that of algae. It is thallus-like and prostrate or erect, and attached to the substratum by unicellular or multicellular rhizoid.
They lack true roots, stems or leaves.

They may possess root-like, leaf-like or stem-like structures.
The main plant body of the bryophyte is haploid. It produces gametes, hence is called a gametophyte.

The sex organs in bryophytes are multicellular. The male sex organ is called antheridium. They produce biflagellate antherozoids.The female sex organ is called archegonium is flask -shaped and produces a single egg.
Theantherozoid are released into water where water where they come in contact with archegonium.
An authrozoids fuses with the egg to produce the zygote. Zygotes do not undergo reduction division immediately. They produce a multicellular body called a sporophyte.
The sporophyte is not free living but attached to the photosynthetic gametophyte and drives nourishment from it.
Some cells of the sporophytes undergo reduction division (meiosis) to produce haploid spores. These spores germinate to produce gametophyte

Economic importance of Bryophytes

Soil conservation :- Mosses grow in dense mates over the soil surface. They bind the soil particles and prevent soil erosion by running water.
Formation of soil :- Mosses along with lichen play a very important role in the formation of soil over the bare rocky surface. They grow on rock and add organic matter to the substratum after their death . It makes the rock surface suitable for the growth of higher plants.
Peat :-species of sphagnum, a moss, provide peat that have long been used as fuel, and as packing material for trans - shipment of living material because of their capacity to hold water.

LIVERWORTS

They do not have true roots, stems or leaves.
They have an above ground leaf like structure, know as thallus, and an underground structure,known as a rhizoid
Liverwort grow usually in moist, shady habitats such as banks of streams, marshy ground, damp soil, bark of trees and deep in the woods.
The plant body of liverwort is thalloid as in marchantia. The leafy members like porella have tiny leaf-like appendages in two rows on the stem-like structure.
Asexual reproduction occurs by means of fragmentation or by the formation of specialized structures called gemmae.

Gemmae formation is an important form of sexual reproduction in many species of liverwort and mosses.

During sexual reproduction the sex organs antheridia (male) and archegonuia (female) are produced either on the same (Riccia) Or on different thallus (marchantia).
In marchantia sex organ are Present on stalked recetcles. The male sex organ are present on antheridiophore and female sex organ are borne on the archegoniophore.
Fusion of gamete result in the formation of zygote which develops into an embryo.
The embryo in turn develops into sporophytes (diploid) .
The sporophytes are differentiated into foot, seta and capsule. Within the capsule, the spore mother cells undergo meiosis to produce the haploid spores. Spores on liberation germinate into the haploid free -living gametophyte.

Mosses

The predominant stage of the life cycle of a moss is the gametophyte which consists of protonema and leafy stage.
The plant body is a leafy gametophyte which has multicellular and branched rhizoids.

They consist of upright, slender axis bearing spirally arranged leaves.This stage bears the sex organs.
In sexual reproduction, the sex organs are present on the same plant but on different branches.
Each antheridium produces a number of flagellate antherozoids.
Each archegonium produces a fertile egg. Fusion Of gamete with the help of water leads to the formation of zygote.
The zygote develops into a sporophyte which is differentiated into foot, seta and capsule.

The capsule encloses two spore sacs, where spores are formed by meiosis.
The mosses have an elaborate mechanism of spore dispersal.
Thespore on liberation germinates into a creeping,green, branched and frequently filamentous in mosses is by fragmentation and budding in the secondary protonema.
The leafy stage develops from the secondary protonema as a lateral bud.

Examples : Funaria, polytrichum and sphagnum .

PTE PTERIDOPHYTA

The pteridophyta include horsetail and ferns. Pteridophyta are used for medicinal purposes and as soil -binders.
They are also frequently grown as ornamentals.
Evolutionary, they are the first terrestrial plants to possess vascular tissue - Xylem and phloem.
The pteridophytes are found in cool, damp and shady places though some may flourish well in Sandy - soil conditions.
In pteridophytes, the main plant body is a sporophyte which is differentiated into true root,stem and leaves.

These organs possess well - differentiated vascular tissue.
The live In pteridophytes are small (microphylls) as in selaginella or large (Macrophylls) as in ferns.

The sporophytes bear sporangia that are suspended by leaf-like appendages called sporophylls.
In Some cases sporophyll may form distinct compact structures called strobili or cones (selaginella, equisetum)
The sporangia produce spores by meiosis in spore mother cells.
The spore germinates to give rise to inconspicuous, small but multicellular free living, mostly photosynthetic thalloid gametophytes called prothallus.
These gametophytes require cool, damp, shady places to grow. Because of this specific restriction to narrow geographical requirement and need for water for fertilisation, the spread of living pteridophyta is limited and restricted to narrow geographical regions.
The gametophytes bear male and female sex organs called antheridia and archegonia,respectively.
Water is required for transfer of antherozoids - the male gamete released from the antheridia,to the mouth of archegonium.
Fusion of male gamete with the egg present in the archegonium results in the formation of zygote.
Zygote thereafter produces a multicellular well- differentiated saprophyte which is the dominant phase of the pteridophytes.

Life cycle of homosporous pteridophytes Examples : eqistem ,psilotum and lycopodium.

In majority of the pteridophytes all the spores are of similar kinds :such plants are closed homosporous.

selaginella and salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous.
The megaspore and microspore germinate and give rise to female And male gametophytes, respectively.
The female gametophytes in these plants are retained on the parent sporophytes for variable periods.
The development of the zygote into young embryos takes place within the female gametophytes.

Life cycle of heterosporous pteridophytes Example : Selaginella, marselia and salvinia.

This event is a precursor to the seed habit considered an important step in evolution.

The pteridophyta are further classified into four classes :

Thank you everyone

Kareena lohia