Bryophytes

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The term Bryophyta came up from the word ‘Bryon’  which means mosses and phyton meaning plants. Bryophyta includes embryophytes like mosses, hornworts and liverworts. These are the plants that grow in shady and damp areas and are small in size. They lack vascular tissues. They reproduce through spores instead of producing flowers and seeds.The study of bryophytes is called Bryology.


Why are Bryophytes Called Amphibians of Plants?

Bryophytes are called “amphibians of the plant kingdom” because they’re the terrestrial plants but require water to finish their life cycle at the time of sexual reproduction.


General Characteristics of Bryophytes:

  • Plants occur in damp and shaded areas.

  • The plant body is thallus like, i.e. prostrate or erect.

  • It is attached to the substratum by rhizoids, which are unicellular or multicellular.

  • They have a root-like, stem-like and leaf-like structure and lack true vegetative structure.

  • Plants lack the vascular system (xylem, phloem).

  • The dominant, a part of the plant body is gametophyte which is haploid.

  • The thalloid gametophyte is divided into rhizoids, axis and leaves.

  • The gametophyte bears multicellular sex organs and photosynthetic.

  • The antheridium produces antherozoids, which are flagellated.

  • The shape of an archegonium is a sort of a flask and produces one egg.

  • The antherozoids fuse with egg to make a zygote.

  • The zygote develops into a multicellular sporophyte.

  • The sporophyte is semi-parasitic and dependent on the gametophyte for its nutrition.

  • Cells of sporophyte undergo meiosis to form haploid gametes which form a gametophyte.

  • The juvenile gametophyte is known as protonema.

  • The sporophyte is differentiated into foot seta and capsule.


Classification of Bryophytes

According to the newest classification, Bryophyta is split into three classes:

  1. Hepaticopsida (Liverworts)

  2. Anthocerotopsida (Hornworts)

  3. Bryopsida (Mosses)

A. Hepaticopsida (Liverworts): The name hepaticopsida comes from the word “hepatic” which means liver. Liverworts come under this class.


Hepaticopsida is Further Divided into 4 Orders:

  1. Marchantiales (e.g. Riccia, Marchantia)

  2. Sphaerocarpales (e.g. Sphaerocarpos)

  3. Calobryales (e.g. Calobryum)

  4. Jungermanniales (e.g. Pellia)


The Main Characteristics of the Class Hepaticopsida are:

  • Gametophyte plant is either thalloid or foliose.

  • Thalloid forms are dorsiventral, lobed and dichotomously branched.

  • Rhizoids are unicellular, branched and septate.

  • Sex organs are borne dorsally embedded in gametophytic tissues.

  • The sporophyte is a compilation of only capsule (in Riccia) or foot, seta and capsule (in Marchantia).

  • The columella is absent in the capsule.

  • Sporogenous tissues develop from endothecium.


Reproduction:

  1. Asexual Reproduction: It takes placer by the formation of gemmae or by the process of fragmentation. Gemmae are produced inside gemma cups. Gemmae are green and multicellular and are also are asexual in nature. The gemma cup develops into a newly born plant after detaching from the parent plant.

  2. Sexual Reproduction: Sexual reproduction: Antheridium (male organ) and archegonium (female organ) could also be present on an equivalent thalli or different thalli. They produce sperm and egg respectively. After fertilisation zygote is formed. The zygote develops into a diploid sporophyte, a couple of cells of the sporophyte undergo meiosis to make haploid spores. These spores become haploid gametophytes, which are free-living and photosynthetic.


B. Anthocerotopsida (Hornworts): There are around 300 species present during this class. They are commonly known as hornworts. It has only one order i.e. Anthocerotales. Examples: Anthoceros, Megaceros, Notothylas.


The Main Features are:

  • The gametophytic body is flat, dorsiventral, simple thalloid and has no internal differentiation.

  • Rhizoids are smooth-walled.

  • Each cell has one chloroplast with a pyrenoid.

  • Sex organs are present dorsally embedded in the thallus.

  • Sporogenous tissues develop from amphithecium.

  • Pseudoelaters are present in the capsule.

  • The columella is present within the capsule, which originates from endothecium.


Reproduction:

  1. Asexual Reproduction: Vegetative propagation takes place by the process of fragmentation of thallus and by tubers, which are formed under unfavourable conditions.

  2. Sexual Reproduction: They reproduce sexually with the help of  waterborne sperm that travels from antheridium to archegonium. A fertilised egg develops into sporophyte. Sporophyte splits lengthwise to release spores which become a gametophyte.


C. Bryopsida (Mosses): It’s the important class of Bryophyta with around 1400 species. They are commonly called mosses. Examples: Funaria, Polytrichum, Sphagnum.


Bryopsida is Further Divided Into 5 Classes:

  1. Bryales

  2. Andriales

  3. Sphagnales

  4. Polytrichales

  5. Buxbaumiales

The Main Features are:

  • The gametophyte is divided into protonema and foliose gametophore.

  • Foliose is formed of stem as an axis and leaves without midrib.

  • Rhizoids are multicellular with oblique septa.

  • Sex organs are borne apically on stem.

  • Elaters are absent.

  • The sporophyte is differentiated into foot, seta and capsule.

  • Sporogenous tissues develop from endothecium.

  • Columella is present.

  • Seperation of the lid is the result of Dehiscence of the capsule.


Reproduction:

  1. Asexual Reproduction: Asexual reproduction takes place by budding and fragmentation of the secondary protonema.

  2. Sexual Reproduction: Antheridia and archegonia are present at the apical part of leafy shoots. After fertilization sporophyte is produced, which is more differentiated than liverworts. The gametophyte develops from the spores.


Examples of Bryophytes

Bryophytes consist of around 20,000 plant species. Bryophytes are divided into liverworts, mosses and hornworts. Some common examples are:

Liverworts:

  • Marchantia

  • Riccia

  • Pellia

  • Porella

  • Sphaerocarpos

  • Calobryum


Mosses:

  • Funaria

  • Polytrichum

  • Sphagnum


Hornworts:

  • Anthoceros

  • Notothylas

  • Megaceros


Ecological Importance of Bryophytes

Bryophytes have great ecological importance. Mosses and lichens are the first organisms to colonise rocks.

  • They decompose the rock making it suitable for the expansion of the higher plants. Soil formation takes place by the acidic secretion that causes due to the death and decay of mosses. 

  • Bryophytes grow densely so act as soil binders.

  • Mosses play an important role in bog succession. The thick mat formed of mosses forms suitable substratum for germination of hydrophilic seeds due in the presence of water and humus. In the meanwhile, the dead and decayed mosses and hydrophilic plants form a solid soil for mesophytic development.

  • They prevent erosion of soil by reducing the impact of the falling rain.

  • They reduce the quantity of run-off water because of their water holding capacity. 

  • They help in recycling of the nutrients. 

  • They act as a rock builder. These plants decompose bicarbonate ions resulting in the precipitation of insoluble calcium carbonate. The mineral deposit continues to increase and therefore extends over several hundred square feet.


Economic Importance of Bryophytes

  1. Medicinal Uses:

    • Sphagnum is employed in dressing as it has high absorptive power and a few antiseptic property for filling absorptive bandages in replacement of cotton for the treatment of boils and discharging wounds

    • Marchantia has been employed to cure pulmonary tuberculosis and affliction of liver

    • The decoction of dried sphagnum is used in the treatment of acute haemorrhage and eye infections

    • Peat-tar is antiseptic and used as a preservative. Polytrichum species has shown to dissolve stone in kidney and gallbladder

    • Antibiotic substances are often extracted from certain bryophytes having antibiotic properties

  2. In Research: Mosses and liverworts are used in research in the field of genetics. The mechanism of sex determination within the plant is discovered in liverworts

  3. Packing Material: Dried mosses make superb packing for fragile goods like glassware, bulbs. For trans-shipment of living material like cuttings and seedlings as they need water retention capacity

  4. Food: Some mosses provide food for herbaceous mammals, birds and other mammals

  5. As Indicator Plants: Some bryophytes grow during a specialised area and may be used as an indicator for acidity and basicity of the soil. E.g. Polytrichum indicated the acidity of the soil, Tortella species grow well within the soil rich in lime or other bases and occur as calcicoles

  6. In seedbeds: Because of its water retention capacity, it is used in seedbeds, greenhouses, nurseries to root cuttings. Sphagnum is additionally wont to maintain high soil acidity required by certain plants

  7. Peat Formation: Sphagnum is additionally referred to as sphagnum. Peat is formed by slowing down the decaying process. The gradual compression and carbonisation of partially decomposed vegetative matter in bogs produce a dark coloured substance called Peat.

  8. It is used as a fuel.

  9. Lower layers of peat form coal.

  10. Peat is also used in the production of ethyl alcohol, ammonium sulphate, ammonia, dye, paraffin, tannins etc.

  11. It improves soil texture in horticulture.

  12. Formation of Stone: The travertine rock deposits are extensively used as a building stone.

FAQ (Frequently Asked Questions)

Q1. What are Bryophytes?

Ans - The term Bryophyta came up from the word ‘Bryon’  which means mosses and phyton meaning plants. Bryophyta includes embryophytes like mosses, hornworts and liverworts. These are the plants that grow in shady and damp areas and are small in size. They lack vascular tissues. They reproduce through spores instead of producing flowers and seeds.The study of bryophytes is called Bryology.

Q2. Mention Some of the General Characteristics of Bryophytes.

Ans - Some of the characteristics are :

  • Plants occur in damp and shaded areas.

  • The plant body is thallus like, i.e. prostrate or erect.

  • It is attached to the substratum by rhizoids, which are unicellular or multicellular.

  • They have a root-like, stem-like and leaf-like structure and lack true vegetative structure.

  • Plants lack the vascular system (xylem, phloem).

  • The dominant, a part of the plant body is gametophyte which is haploid.

  • The thalloid gametophyte is divided into rhizoids, axis and leaves.

  • The gametophyte bears multicellular sex organs and photosynthetic.

  • The antheridium produces antherozoids, which are flagellated.

  • The shape of an archegonium is a sort of a flask and produces one egg.

  • The antherozoids fuse with egg to make a zygote.

  • The zygote develops into a multicellular sporophyte.