Introduction to bryophytes - class-XI

Sexual reproduction involves the mixing of genes from two different parents to give offspring with a genetic make-up similar to, but different from, each parent. In Bryophytes the process requires the production of male gametes (sperm), female gametes (eggs) and some means of getting the sperm to the eggs. The gametes are produced on the gametophytes. Water is essential for sexual reproduction in Bryophytes, since it is water that carries the sperm to the egg.

Bryophytes include the various mosses commonly growing in moist shaded areas. Mosses from dense mats on the soil, thus reduce the impact of falling rain and prevent soil erosion.

Bryophytes are the cryptogamae, which do not bear flowers and seeds. They are non-vascular land plants of moist habitat, in which diploid sporophyte lives as a parasite on independent haploid gametophyte. 
Pteridophytes are vascular cryptogams due to the presence of vascular tissues in the plant body.
Gymnosperms and Angiosperms are Phanerogams, which possess flowers and seeds.

In Bryophyta, organs are referred to as "Leaf like' and 'Stem like' and not the true leaf and stem, because leaf and stem have the complex tissues, which perform the water and food conduction. Bryophytes being the lower plants do not have true leaf, stem and roots. They do not have vascular tissue system. 

Bryophytes are non vascular land plants. Fungi and algae belongs to the group Thallophyta, which is the lower plants than Bryophytes on land. Pteridophytes are the first vascular plants on land with all vascular tissues. Since, Bryophytes do not have true leaf, stem and roots, do not have vascular tissues for the water and food conduction, water is absorbed by diffusion process. 

Bryophyta includes the simplest and primitive land plants, which are characterised by the persence of independent gametophyte and parasitic sporophyte. They are non-vascular land plants with undifferentiated plant body. the plant body is not divided into true leaves, stem and roots. In all bryophytes the ecologically persistent, photosynthetic phase of the life cycle is the haploid, gametophyte generation rather than the diploid sporophyte; bryophyte sporophytes are very short-lived, are attached to and nutritionally dependent on their gametophytes and consist of only an unbranched stalk, or seta, and a single, terminal sporangium. 

Bryophytes are also called as the amphibians of the plant world due to their preference for moist habitat and dependence on water for fertilization, despite being land plants.

Bryophytes are the non-vascular terrestrial plants of moist habitats in which a multicellular diploid sporophyte lives as a parasite on an independent multicellular haploid gametophyte. Bryophytes include the mosses and liverworts that are found commonly growing in moist shaded areas in the hills. The plant body of bryophytes is more differentiated than that of algae. It is thallus-like and maybe prostrate or erect. They lack true roots. The plant body is attached to the substratum by root-like structures called rhizoids. The rhizoids may be unicellular or multicellular.

Xylem and phloem are vascular tissues which are a complex conducting tissue formed of more than one type of cell. Xylem transports water and minerals while phloem conducts organic food. Bryophytes do not have to conduct tissues. They are non-vascular terrestrial plants of moist habitats in which a multicellular diploid sporophyte lives as a parasite on an independent multicellular haploid gametophyte. Pteridophytes are the first terrestrial plants to possess conducting tissues.

Bryophyta is known as amphibians of the plant kingdom as they can survive both on land and water. They lack fully developed vascular tissue. They do not have true roots rather they have a root-like structure known as rhizoid. They originate from lower epidermal cells of bryophytes. They are similar in function to root as it helps in the absorption of water.

Bryophyta acts as the connecting link between algae (Thallophyta) and Pteridophyta. Their body is differentiated more than algae but lacks true root, stem, and leaves. They do not have vascular tissue like algae but have multicellular sex organ and requires water for fertilization like Pteridophyta.

The first land inhabiting plants are bryophytes.
The evolution of plants has resulted in widely varying levels of complexity, from the earliest algal mats, through bryophytes, lycopods, ferns to the complex gymnosperms and angiosperms of today.  bryophytes (liverworts, mosses and hornworts) have developed the gametophyte, with the sporophyte becoming almost entirely dependent on it; vascular plants have developed the sporophyte, with the gametophyte being particularly reduced in the seed plants.

Amphibians are those organisms which live on both land and in water. Bryophytes are called amphibians of the plant kingdom because these plants, though they live in soil, they need water for sexual reproduction. The sperm of bryophyte (antherozoids) are flagellate and need water to swim to the eggs. In other words, as these plants need water for reproduction unlike other plants, they are called as amphibians. 

Funaria is a genus of approximately 200 species of moss. These are primitive multicellular, autotrophic, shade-loving, amphibious plants. They reproduce by spore formation. They have no vascular system. Conducting tissue present is parenchyma. Root like structures called rhizoids are present. They show alternation of generation i.e., the gametophytic stage alternates with the sporophytic stage.

Bryophytes are considered the first group of land plants, having evolved from aquatic ancestors to colonize terrestrial environments.

Bryophytes are embryophytes that are non-vascular i.e., they have no xylem and phloem. Pteridophytes are vascular plants i.e., plants with xylem and phloem, that reproduce and disperse via spores.
The dominant phase in bryophyte is gametophyte while the dominant phase in pteridophyte is sporophyte. Bryophytes have no true roots while pteridophyte have true roots. Bryophytes have no vascular tissues while pteridophytes have vascular tissues.

Bryophytes are small non-vascular plants. They are called amphibians of the plant kingdom because these plants are found near freshwater. But their sperms also called antherozoids are flagellate and need water to swim and reach the eggs in order to fertilize it. Hence they need water for sexual reproduction. Thus the correct answer is option B.

In mosses, the capsule is the terminal part of the sporophyte generation, which is responsible for producing spores.

Funaria and Marchantia are crytogamae, they have thin, soft leaves and roots. These are the characteristic of division Bryophyta.
Thallophyta and Pteridophyta are also cryptogamae but Thallophyta do not have root, stem and leaves and Pteriodophyta have root, stem and leaves. So, they are not the correct options as Funaria and Marchantia have false root, stem and leaves. 
Phanerogams is not the correct answer because phanerogams are flowering plants while Funaria and Marchantia are non-flowering plants.

The plant kingdom is divided into two sub-kingdoms: Cryptogamae and Phanerogamae.

Bryophytes are small, non-vascular plants, such as mosses, liverworts and hornworts. They play a vital role in regulating ecosystems because they provide an important buffer system for other plants, which live alongside and benefit from the water and nutrients that bryophytes collect. Some bryophyte species are amongst the first to colonise open ground. Bryophytes are also very good indicators of habitat quality as many plant species in this group are sensitive to levels of moisture in the atmosphere, which are lower in disturbed habitats because there is less shade. Mushrooms, ferns or cycas are not bryophytes. 

Bryophytes are small, non-vascular plants, such as mosses, liverworts and hornworts. They play a vital role in regulating ecosystems because they provide an important buffer system for other plants, which live alongside and benefit from the water and nutrients that bryophytes collect. Some bryophyte species are amongst the first to colonise open ground. Bryophytes are also very good indicators of habitat quality as many plant species in this group are sensitive to levels of moisture in the atmosphere, which are lower in disturbed habitats because there is less shade. 

Bryophytes and pteridophytes are characterized by having well-developed archegonia with a neck consisting of multiple rows of cells, a feature that distinguishes them from seed plants.

Marchantia is well known for its elaters, which are hygroscopic cells that help in the dispersal of spores from the capsule.

Marchantia is a bryophyte; its sporophyte is dependent on the gametophyte for nutrition and is not independent, unlike the sporophyte of pteridophytes.

In Marchantia, the archegonia are protected by a specialized structure called the perichaetium (or involucre).

The antherozoids of Marchantia are biflagellate, short, and curved, designed for swimming to the archegonia in a water film.

Gemmae also occur on the protonemal branches of some Funaria species.

In Marchantia, both the elater mother cells and spore mother cells are derived from the same sporogenous tissue within the capsule, thus belonging to the same generation.

Marchantia reproduces vegetatively through gemmae, which are produced in specialized structures called gemma cups on the dorsal surface of the thallus.

The answer is option C i.e. "Porella/ Madotheca"

Plant body is thalloid in Marchantia. An organism or structure resembling a thallus is called Thalloid.

The archegoniophore is a specialized stalked structure that bears the archegonia in Marchantia.

Marchantia polymorpha is dioecious (separate male and female plants) and produces antheridiophores and archegoniophores. It is homosporous, not heterosporous, and its sporophyte does possess a foot and seta.

All the listed pairs are standard descriptions of sporophyte characteristics in various bryophytes: Marchantia (irregular), Scapania (two halves), Anthoceros (bulbous foot), and Sphagnum (no seta).

Reindeer moss and Iceland moss are not true mosses despite their common names. They are actually composite organisms formed by a symbiotic association between fungi and algae, which classifies them as lichens.

Funaria is a genus of moss. In Funaria, rhizoids are present. They are primitive multicellular plants. They are autotrophic plants. They show alteration of generation. They reproduce by spore formation.

The main, independent, and photosynthetic plant body of Funaria and other mosses is the haploid gametophyte. The sporophyte is physically attached to and nutritionally dependent on the gametophyte, making the plant body predominantly gametophytic.

The leaf of Funaria belongs to the haploid gametophytic generation, meaning the leaf cells are haploid (n = 5). The primary protonema develops directly from the germination of a haploid spore, so its cells are also haploid and will contain the same number of chromosomes, which is 5.

Hepaticites is a fossil genus of liverworts (Hepaticae) and is widely recognized as one of the most complete fossil bryophytes discovered.

Funaria has a radial symmetry with a once branched axis or stem, a number of spirally arranged leaves and branched colourless multicellular rhizoids. The axis is aerial, erect, slender and monopodial branched.

Fertilisation of Funaria occurs in water. The antherozoids are released into the water where they swim and reach archegonium, An antherozoid fuses with the egg to produce the zygote. thus, an external layer of water is essential for the swimming of male gametes to the archegonia.

Bryophytes shows two morphologically distinct heteromorphic generations, i.e. gametophytic and sporophytic generations. Gametophytic generation is the dominant phase of life cycle and in general the term 'plant body' is used to represent this phase.

The life cycle of higher plants is dominated by the sporophyte stage, with the gametophyte borne on the sporophyte. In ferns, the gametophyte is free-living and very distinct in structure from the diploid sporophyte. Pteridophytes also have their multicellular sex organs covered in the multicellular jacket later.

Certain features in bryophytes are not completely supporting the life of bryophytes on land like:

Bryophytes require water to reproduce. The male gametes (sperm) require water to reach the female gamete. The fact that they are non-vascular plant only accounts for their small size and not why they are dependent on water.

Pteridophytes have a well-differentiated plant body with vascular tissues. Therefore, option B is incorrect. 
Gymnosperms have a well-differentiated plant body with vascular tissues. They produce naked seeds. Therefore, option C is incorrect. 
Angiosperms have a well-differentiated plant body with vascular tissues. They produce seeds enveloped in fruits. Therefore, option D is incorrect. 
Bryophytes have a well-differentiated plant body with stem and leaf-like structures. They do not have conducting or vascular tissues, i.e, xylem, and phloem. Thus, they are called non-vascular cryptogamic plants. They are very small in length usually 2 cm to 15 cm. So they do not need mechanical tissues.  Therefore, option A is correct.

The differences between thallophyta and bryophyta are :
(i) Thallophyta: Body is thallus like, not differentiated into root, stem and leaves. Sex organs single celled. Example: Spirogyra.
(ii) Bryophyta: Plant body is differentiated into leaf and rhizoids. Sex organs multicellular. Example : Moss

Archegonium is the the female reproductive organ in ferns and mosses. An archegonium also occurs in some gymnosperms, e.g., cycads and conifers. It is a flask-shaped structure, consists of a neck, with one or more layers of cells, and a swollen base and the centre, which contains the egg. Neck-canal cells, located above the egg, disappear as the archegonium matures, thus producing a passage for entry of the sperm. The sperm are produced in the corresponding male reproductive organ, the antheridium.

Marchantia is a liverwort. While it contains oil cells and starch grains in its thallus, and may show various cellular structures, it does not contain Nostoc, which is a cyanobacterium often found in the thallus of Anthoceros (hornworts) as a symbiont.

Sphaerocarpos is a well-known genus of liverworts, which are classified under the division Bryophyta.

Marchantia polymorpha is dioecious (statement 1 is correct) and produces specialized structures called antheridiophores and archegoniophores (statement 2 is correct). The sporophyte does possess a foot and seta (making statement 3 incorrect), and it is homosporous, not heterosporous (making statement 4 incorrect).

• Alternation of generations is a term primarily used to describe the life cycle of plants (taken here to mean the Archaeplastida). A multicellular gametophyte, which is haploid with n chromosomes, alternates with a multicellular sporophyte, which is diploid with 2n chromosomes, made up of n pairs. 
• A mature sporophyte produces spores by meiosis, a process that reduces the number of chromosomes to half, from 2n to n. Because meiosis is a key step in the alternation of generations, it is likely that meiosis has a fundamental adaptive function. 
• The nature of this function is still unresolved, but the two main ideas are that meiosis is adaptive because it facilitates repair of DNA damages and/or that it generates genetic variation. In liverworts, mosses, and hornworts, the sporophyte is less well developed than the gametophyte and is largely dependent on it. 
• Although moss and hornwort sporophytes can photosynthesize, they require additional photosynthate from the gametophyte to sustain growth and spore development and depend on it for the supply of water, mineral nutrients and nitrogen.
• In ferns, the gametophyte is a small flattened autotrophic prothallus on which the young sporophyte is briefly dependent for its nutrition.

Anthoceros has a sporophyte with a foot and intercalary meristem. Marchantia has gemma cups. Pteris (a fern) has sori covered by a false indusium. Ginkgo is a gymnosperm (embryophytic, tracheophytic, archegoniate).

Slime pores are found in :

In mosses like Funaria, the dominant, free-living, and photosynthetic phase is the gametophyte, while the sporophyte is a smaller structure dependent on it. Thus, the plant body is predominantly gametophyte with a dependent sporophyte.

The haploid phase in the life cycle of plants is called Gametophyte. It is a haploid phase. It is well developed in bryophytes and highly reduced in angiosperms.

The thallus is dorsiventral and closely appressed to the substrate. 

Funaria features include a protonema stage (a), leafy gametophores (c), a haplodiplontic life cycle (f), and propagation via fragmentation (h). Features like prothallus (b) belong to pteridophytes, and true plant organs (g) belong to vascular sporophytes, making option C and others incorrect.

In the bryophyte life cycle, the fusion of gametes forms a diploid zygote, which then undergoes mitotic divisions to develop into the multicellular sporophyte.

Marchantia is a large liverwort and is also called as umbrella liverwort. Marcantia is dioicous and hence has seperate male and female plants.

The statement that antherozoids are non-motile is incorrect because bryophyte male gametes (antherozoids) are biflagellate and motile, requiring water to swim toward the archegonium for fertilization. All other listed statements about bryophytes are true.

Peat, also known as turf, is an accumulation of partially decayed vegetaation or organic matter.Sphagnum "moss", also called peat moss, is one of the most common components in peat, although many other plants can contribute.

Sphagnum is one of the most important plant genera in the world. Sphagnum is one of the few bryophyte genera able to dominate an ecosystem. A healing ointment prepared by Sphagnum leaves mixed with grease is used in the treatment of cuts and wounds. The decoction prepared by boiling dried Sphagnum in water, is used in the treatment of acute haemorrhage. This decoction is used to cure diseases of eyes. The lakes where sphagnum grows are called as Sphagnum bogs. These are well known to produce peat in acidic water. The bog water is antiseptic and has astringent properties. Sphagnum exhibit strong antibacterial properties against Gaffkeya tetragena and Staphylococcus aureus. Sphagnum peat is suitable for production of low and intermediate BTU gas as well as hydrogen , ethylene , natural gas , methanol and gasoline. Sphagnum is used as an effective filtering and absorption agent for the treatment of waste water and effluent of factories with acid and toxic discharge consisting of heavy metals particularly Ag, Pb, Cu , Hg, Fe , Sb and organic substances like detergents, dyes, microorganisms and soils.

Peat is a dead form of Sphagnum moss. The lakes where sphagnum grows are called as Sphagnum bogs. These are well known to produce peat in acidic water.

Sphagnum is one of the most important plant genera in the world. 
Sphagnum tends to acidify its surroundings. The acidity inhibits bacterial and fungal growth.
Living Sphagnum plants have an impressive water holding potential, with a number of species able to hold 20 or more times their own weight in water. Given the ability to absorb large amounts of water Sphagnum plays a significant role in water regulation. Sphagnum absorbs a vast quantity of water during any heavy downpour or after snow melt and then releases much of that water in a more gradual flow over a much longer period.
Peat is a valuable fuel like coal, consists of Sphagnum plants, which got compacted and fossilized over the past thousands of years.

Sphagnum that generally grows in bogs are slightly antiseptic and can absorb large amount of water i.e., upto 18 times its weight. On account of these properties they may be used for filling absorbent bandage in place of cotton, in the hospitals. The plants absorb and hold water in them. For these properties they are used in seed beds and green houses to root cuttings. They are also used to maintain high soil acidity required by certain plants.

Bryophytes can colonize any rock, soil or any barren land. They have the ability to absorb water from rain and mist and to trap nutrients dissolved in rain and mist drops. They Dead and decaying bryophytes release nutrients and make a path for soil formation. Hence, they are the first organism in primary succession. Thus, the correct answer is option B.

Sphagnum (peat moss) is of significant economic importance because it is used as fuel, as packing material for shipping plants, and for its high water-holding capacity.

Peat consists of deposits of vegetable matter which have accumulated in bogs and swamps and slowly decomposed, becoming somewhat carbonised and compacted. It is dark brown in colour. Peat is built by Sphagnum moss, for this reason, Sphagnum is called peat moss. Peat is used as fuel and manure.

Sphagnum efficiently absorbs moisture because of its close overlapping leaves and sponge-like matting of the branches around the stem, and also the microscopic structure of the leaves. The elongated living cells form a network running throughout the leaf but it is a second set of cells, dead and empty, that provide the plant’s capacity for absorption. Their porous cell walls allow water to flow in and inflate them. Each cell can absorb up to 25 times its own weight of liquid. Sphagnum has found use since ancient times in home-made sanitary towels and as a form of nappy. Sphagnum has been used to staunch wounds for over 1,000 years. Scottish soldiers used it at the battle of Flodden in 1513. Its use for wounds waned until the 1914–18 war, when it soon became obvious to surgeons that the need for dressings would be immense due to the unexpected numbers of military wounded.

Bryophytes are known as 'amphibians of plant kingdom' because they are adapted to land as well as water habitats. In their vegetative structure, bryophytes have become adapted to land. But they depend on water for sexual reproduction because the swimming habit is retained by their sperms.