SlideShare a Scribd company logo
1 of 23
Download to read offline
LICHENS
BY
Dr P B MALLIKHARJUNA
GFGC YB
25-4-2020
LICHENS
 Lichens are the most important symbiotic living organisms / plants on
the earth.
 Theophrastus (371-284 BC), the Father of Botany, to denote the
superficial growth on the tree bark, coined the term ‘LICHEN’.
 Lichenology is a branch of Botany that deals with the study of Lichens.
 Acharius (1798), a Swedish lichenologist, is the Father of Lichenology.
 Lichens are one of the largest group of plants consisting about 500
genera and 18000 species included in 9 orders.
 A lichen can be defined as “the dual organism with symbiotic
(mutualistic) association of a fungus with an alga”.
 Mycobiont: is the fungal partner. It is the exhabitant, dominant,
colourless, protective and reproductive partner.
 Phycobiont:is the algal partner. It is the inhabitant, recessive,
coloured autotrophic partner.
Although, lichens are the symbiotic associations, the
relationship between a fungus and an alga is like a Master
and Slave. It is known as “HELOTISM” (Crombie,1885).
Fungus is the Master and alga is the Slave
Occurrence: Lichens are one of the most widely distributed plants ranging from the polar to the
deserts, and aquatic bodies.
 Lichens are the dominant vegetation both in the Arctic and Antarctic regions.
 They will grow as lithophytes, xerophytes, epiphytes, mesophytes, and hydrophytes.
 Some of these are Clandonia rangiferina (Reindeer moss), Peltigera (Aquatic lichen),
Gyrophora (White lichen), Graphis, Parmelia, Haematomma, Cora, Dictyonema, etc.
 They show great variation in their size, shape, structure, morphology, growth rate and
ecology.
 In a typical lichen, the fungal partner (the Mycobiont) is the most abundant component, which
accounts for 90-95% of the total biomass, whereas the algal partner( Phycobiont) accounts for
5-10%.
 The fungal hyphae form a close network resembling a tissue like mass with the algal cells
often embedded in it.
 Lichens based on their habitat
(distribution), external morphology,
internal anatomy, and the partners
involved (fungal and algal) are classified
into several types.
1) Based on their Habitat: There are three
types of lichens,viz.,
a) Saxicoles (which grow on the rocks),
b) Corticoles (which grow on the Bark), and
c) Terricoles (which grow on the soil).
1) Based on the Habit / Morphology:
There are three types of lichens viz.,
a) Crustose lichens: These are the most common type
with thin mat like thalloid plants, firmly attached to
the substratum. Ex: Graphis, Haematomma (More
common on the barren rocks). The pioneers of the
xeorsere type of plant sucession
b) Foliose lichens: These are thalloid; flatten leaf like
plants attached to the substratum through rhizines.
Ex: Parmelia (More common in the tropical forests
as corticoles)
c) Fruiticose lichens: These are usually a small shrub
like vertically or pendulously growing plants. They
are common in the temperate and polar regions. Ex:
Cladonia
1) Based on the Internal Structure:
Lichens may be of a) Homoimerous
and b) Heteroimerous
In Homoimerous lichens, the fungal
hyphae are loosely arranged. Several
crustose lichens belongs to this
category.
In Heteroimerous lichens, the fungal
hyphae are thick and compact and
thereby surrounding the alga.
1) Based on the Fungal Partner:
Lichens can be classified into three types viz., a)
Ascolichens, b) Basidiolichens and c)
Deuterolichens
a) Ascolichens: The fungal partner belongs to the class
Ascomycetes. These are the abundant type. Over 98%
lichens are Ascolichens. Ex: Parmelia, Graphis.
Apothecia, perithecia and pseudothecia are the
common fruiting bodies. They may be
(Apothecia) or (Perithecia).
b) Basidiolichens: The fungal partner belongs to the class
Basidiomycetes. They are very less in number (<1%).
Some of these are Cora, Corella and DIctyoma. They
produce pycnidial cups.
1) Based on the algal partner:
Generally, either green alga or the blue-green
alga will be the algal partner of lichens. Hence,
lichens are a) Chlorophycophyllous lichens and
b) Cyanophycophyllous lichens.
a) In Chlorophycophyllous lichens, the algal partner is
green alga. 80% of lichens contain green alga as a
phycobiont. Trebouxia (unicellular) is the most
abundant partner followed by Chlorella.
b) In Cyanophycophyllous lichens, the algal partner
belongs to BGA or cayanobacteria which accounts
for ~8%. Some of these are Nostoc, Stigonema,
Rivularia, and Gleocapsa. However, Nostoc is the
most common partner.
HOMOIMEROUS THALLUS OF LICHEN
HETEROMEROUS THALLUS OF LICHEN
REPRODUCTION IN LICHENS:
 Both vegetative/asexual reproduction and sexual reproduction are present
in Lichens.
 The Vegetative Reproduction: takes place very frequently either by the
fragmentation process or by the formation of different types of diaspores
(having both alga and fungus) such as Soredia and Isidia.
 In the vegetative propagation, both the partners are involved and develop
into a new daughter Lichen.
 Fragmentation is the common mode of vegetation where the fragments are
arise either due to the progressive death and decay of older portion or due
to the involvement physical factor.
 Soredia: These are the asexual/vegetative
propagules of Lichens.
o These are small, rounded granules or bud-like
outgrowth, which develop, in the form of a greyish
white or greyish green powder in extensive patches
usually over the upper surface or edges of the thalli of
many species of Lichens.
o It consists of a small group of algal cells surrounded
by a few fungal hyphae.
o Several soredia are present into a cluster often
referred as Sorelia.
 Isidia: These are the asexual/vegetative
propagules of Lichens.
o These are small, conical warts developed on
the upper thallus of many Lichens.
o An isidium is usually surrounded by cortex and
diasporic in composition
o Their shape is highly variable among lichens
ranging from rod shape to coral-like structure.
Ex: Parmelia, Usnea.
Sexual Reproduction: Sexual reproduction occurs in many
Lichens and in this, only the fungal partner (the mycobiont ) is
involved. The role of algal partner is passive or very absent.
 The mode of sexual reproduction in lichens maybe spermatogamy.
 Ascolichens produce the sex organs namely Spermogonium (male)
and Carpogonium (female). After fertilization, they produce the
special fruiting bodies such as Apothecium, Perithecium and some
times Puesdothecia. Ex: Parmelia
 While, the Basidiolichens, produce basispores followed by the
formation of the Pycnidia, as the sexual apparatus. After
spermatogamy, the sexual fruiting body develops as Basidiocarp like
in Agaricus. Ex: Corella.
Sexual reproduction in Ascolichens:
 Since majority of the lichens are with Ascomycetous fungal partner, it will
reproduce sexually by the formation of two different types of sex organs.
 The male reproductive structure is Spermogonium and the female reproductive
sex organ is Carpogonium.
 The spergonium is a flask shaped structure that usually present present upper
surface of the thallus. It is with a pore called ostiole, and several muticelluar
spmertiophores which produce the uni-nucleate spheroidal sermatia.
 The carpogonium is a special cellular filament. It consists of two portions, the
lower coiled portion usually called Ascogonium and it is multi-cellular and
monokaryotic. It lies deep in the medullary region of the thallus.
 The straight upper portion of the carpogonium is called trichogyne and it is
multicellular. The component cells are elongated one with the porous cross
septa.
 The trichogyne receives the spermatia (the male gametes) which in turn
penetrates and finally reaches the corpogonium and subject to fertilization
resulting a diploid cell called ascus mother cell. This cell proliferates into
several asci and whereby the diploid nucleus undergo meiosis and produce
haploid ascospores
 Likewise, so many filaments arise and protrude above the surface of the thallus
and produces the characteristic fruiting bodies viz., 1) Apothecium 2)
Perithecium and 3) Pseudothecia with or without stalk.
Lichen Apothecia
1) Apothecium: is a major type of sexual fruiting body of Ascolichens.
 It is generally round and cup-shaped structure.
 Their colour is highly variable ranging from reddish to black colour.
 In some lichens, the apothecia contain only the mycobiont but the phycobiont is absent. Ex:
Cladonia.
 However, in majority of the lichens, the apothecia possess both the partners. Ex: Parmelia.
Apothecium structure: Apothecium is lined with palisade-like layer cells called
Hymenium.
 The Hymenium consists of a series of elongated cells – the asci, intermixed with sterile
hyphae – the paraphyses.
 Each ascus usually contains eight ascospores (bi-celled).
The liberated ascospores liberated, if come in contact with suitable alga, produce the
new daughter thallus. Otherwise they perish.
1) Perithecium: This is another sexual fruiting body of the
Ascolichens.
 It is much smaller than the apothecium and flask shaped
structure and appears as a small dot on the surface of the
thallus.
 The dark coloured wall bound it.
 The cavity is lined with asci.
 The paraphyses are few in number or totally absent.
 It is embedded in the elevations of the thallus on the
upper side.
 It opens through a small pore called an Ostiole.
ECOLOGICAL ROLE OF LICHENS
1) Lichens are serving as the indicators of Air pollution. Especially they are very sensitive to
the NO2 and SO2 gases.
2) They involve in the soil formation on the rocks called biological weathering.
3) They are the first/pioneer colonizers on a barren rock in the establishment of ecological
plant succession.
4) Some lichens may be used as tools in order to determine the age of the rocks and the past
events occurred called Lichenometry.
ECONOMIC IMPORTANCE OF LICHENS
 Since lichens are rich with secondary metabolites like alkaloids, oils and other substances,
lichens are extensively used in medicine, besides serving as food and fodder to man and
animals. Further, several acids, dyes (orecin, litmus) are extracted. Also using in perfume
and dhoop industries

More Related Content

What's hot (20)

Ascomycotina converted
Ascomycotina convertedAscomycotina converted
Ascomycotina converted
 
Xanthophyceae
XanthophyceaeXanthophyceae
Xanthophyceae
 
Charophyta
CharophytaCharophyta
Charophyta
 
Algae bsc 1
Algae bsc 1Algae bsc 1
Algae bsc 1
 
General characteristics of pteridophytes
General characteristics of pteridophytesGeneral characteristics of pteridophytes
General characteristics of pteridophytes
 
Marchantia
MarchantiaMarchantia
Marchantia
 
basics of Lichens
basics of Lichens basics of Lichens
basics of Lichens
 
Coleochaete
ColeochaeteColeochaete
Coleochaete
 
Algae seminar
Algae seminarAlgae seminar
Algae seminar
 
Algae thallus structure
Algae thallus structureAlgae thallus structure
Algae thallus structure
 
Nostoc
NostocNostoc
Nostoc
 
Riccia ppt
Riccia ppt Riccia ppt
Riccia ppt
 
Marchantia ppt
Marchantia pptMarchantia ppt
Marchantia ppt
 
Algae thallus
Algae thallusAlgae thallus
Algae thallus
 
Habitat and habit of algae
Habitat and habit of algaeHabitat and habit of algae
Habitat and habit of algae
 
General Account of Chlorophyta & Charophyta
General Account of Chlorophyta & CharophytaGeneral Account of Chlorophyta & Charophyta
General Account of Chlorophyta & Charophyta
 
Alteration of generations in bryophytes
Alteration of generations in bryophytesAlteration of generations in bryophytes
Alteration of generations in bryophytes
 
Pentoxylales
Pentoxylales Pentoxylales
Pentoxylales
 
Pteridophyte ppt
Pteridophyte pptPteridophyte ppt
Pteridophyte ppt
 
ALGAE - THALLUS ORGANIZATION.pptx
ALGAE - THALLUS ORGANIZATION.pptxALGAE - THALLUS ORGANIZATION.pptx
ALGAE - THALLUS ORGANIZATION.pptx
 

Similar to Lichens - A general Account

lichens-a-general-account.ppt
lichens-a-general-account.pptlichens-a-general-account.ppt
lichens-a-general-account.pptjaya1992
 
Lichen General Characters by Dr D.Nagaraju
Lichen General Characters by Dr D.NagarajuLichen General Characters by Dr D.Nagaraju
Lichen General Characters by Dr D.NagarajuNagaraj Deshaboina
 
Lichens by Fauzia Razzaq
Lichens by Fauzia RazzaqLichens by Fauzia Razzaq
Lichens by Fauzia RazzaqFauziaRazzaq
 
Botany Bryophytes notes for 1st semester.pptx
Botany Bryophytes notes for 1st semester.pptxBotany Bryophytes notes for 1st semester.pptx
Botany Bryophytes notes for 1st semester.pptxSPChaithanya
 
Diversity in living organisms
Diversity in living organismsDiversity in living organisms
Diversity in living organismsoptims Prime
 
Diversity in Living Organism
Diversity in Living OrganismDiversity in Living Organism
Diversity in Living OrganismEneutron
 
Phycology algae ... presentation
Phycology  algae ... presentationPhycology  algae ... presentation
Phycology algae ... presentationAnzaDar3
 
Diversityinlivingorganisms 130829215931-phpapp02
Diversityinlivingorganisms 130829215931-phpapp02Diversityinlivingorganisms 130829215931-phpapp02
Diversityinlivingorganisms 130829215931-phpapp02Sakala Suresh
 
Order hemiptera True bugs
Order hemiptera True bugs Order hemiptera True bugs
Order hemiptera True bugs NizadSultana
 

Similar to Lichens - A general Account (20)

lichens-a-general-account.ppt
lichens-a-general-account.pptlichens-a-general-account.ppt
lichens-a-general-account.ppt
 
Physcia
PhysciaPhyscia
Physcia
 
Lichens
LichensLichens
Lichens
 
Lichenology
LichenologyLichenology
Lichenology
 
G.C of Lichens.pptx
G.C of Lichens.pptxG.C of Lichens.pptx
G.C of Lichens.pptx
 
Lichens
LichensLichens
Lichens
 
Lichen General Characters by Dr D.Nagaraju
Lichen General Characters by Dr D.NagarajuLichen General Characters by Dr D.Nagaraju
Lichen General Characters by Dr D.Nagaraju
 
Lichens by Fauzia Razzaq
Lichens by Fauzia RazzaqLichens by Fauzia Razzaq
Lichens by Fauzia Razzaq
 
Algae introduction
Algae introductionAlgae introduction
Algae introduction
 
Lichens
LichensLichens
Lichens
 
Anthoceros
Anthoceros Anthoceros
Anthoceros
 
Intro to fungi
Intro to fungiIntro to fungi
Intro to fungi
 
Gymno vs angio
Gymno vs angioGymno vs angio
Gymno vs angio
 
Fungi
FungiFungi
Fungi
 
Botany Bryophytes notes for 1st semester.pptx
Botany Bryophytes notes for 1st semester.pptxBotany Bryophytes notes for 1st semester.pptx
Botany Bryophytes notes for 1st semester.pptx
 
Diversity in living organisms
Diversity in living organismsDiversity in living organisms
Diversity in living organisms
 
Diversity in Living Organism
Diversity in Living OrganismDiversity in Living Organism
Diversity in Living Organism
 
Phycology algae ... presentation
Phycology  algae ... presentationPhycology  algae ... presentation
Phycology algae ... presentation
 
Diversityinlivingorganisms 130829215931-phpapp02
Diversityinlivingorganisms 130829215931-phpapp02Diversityinlivingorganisms 130829215931-phpapp02
Diversityinlivingorganisms 130829215931-phpapp02
 
Order hemiptera True bugs
Order hemiptera True bugs Order hemiptera True bugs
Order hemiptera True bugs
 

More from Mallikharjuna Palle B (15)

ICBN.pdf
ICBN.pdfICBN.pdf
ICBN.pdf
 
CYCAS-1.pdf
CYCAS-1.pdfCYCAS-1.pdf
CYCAS-1.pdf
 
An Introduction to Fungi.pdf
An Introduction to Fungi.pdfAn Introduction to Fungi.pdf
An Introduction to Fungi.pdf
 
Albugo
AlbugoAlbugo
Albugo
 
Puccinia
Puccinia Puccinia
Puccinia
 
Meiosis - The Special Cell Division
Meiosis - The Special Cell DivisionMeiosis - The Special Cell Division
Meiosis - The Special Cell Division
 
Apoptosis - An Introduction
Apoptosis - An IntroductionApoptosis - An Introduction
Apoptosis - An Introduction
 
PLANT NOMENCLATURE
PLANT NOMENCLATUREPLANT NOMENCLATURE
PLANT NOMENCLATURE
 
Systems of Plant Classification
Systems of Plant ClassificationSystems of Plant Classification
Systems of Plant Classification
 
Methods of Vegetative Propagation
Methods of Vegetative PropagationMethods of Vegetative Propagation
Methods of Vegetative Propagation
 
The Embryo sac Structure of Angiosperms
The Embryo sac Structure of AngiospermsThe Embryo sac Structure of Angiosperms
The Embryo sac Structure of Angiosperms
 
PHOTORESPIRATION
PHOTORESPIRATIONPHOTORESPIRATION
PHOTORESPIRATION
 
Endosperm in Angiosperms
Endosperm in AngiospermsEndosperm in Angiosperms
Endosperm in Angiosperms
 
Plant introduction
Plant introductionPlant introduction
Plant introduction
 
DOUBLE FERTILIZATION IN ANGIOSPERMS
DOUBLE FERTILIZATION IN ANGIOSPERMSDOUBLE FERTILIZATION IN ANGIOSPERMS
DOUBLE FERTILIZATION IN ANGIOSPERMS
 

Recently uploaded

Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M⊙ Compa...
Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M⊙ Compa...Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M⊙ Compa...
Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M⊙ Compa...Sérgio Sacani
 
Combining Asynchronous Task Parallelism and Intel SGX for Secure Deep Learning
Combining Asynchronous Task Parallelism and Intel SGX for Secure Deep LearningCombining Asynchronous Task Parallelism and Intel SGX for Secure Deep Learning
Combining Asynchronous Task Parallelism and Intel SGX for Secure Deep Learningvschiavoni
 
Charateristics of the Angara-A5 spacecraft launched from the Vostochny Cosmod...
Charateristics of the Angara-A5 spacecraft launched from the Vostochny Cosmod...Charateristics of the Angara-A5 spacecraft launched from the Vostochny Cosmod...
Charateristics of the Angara-A5 spacecraft launched from the Vostochny Cosmod...Christina Parmionova
 
Loudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxLoudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxpriyankatabhane
 
Unit-V-Introduction to Data Mining.pptx
Unit-V-Introduction to  Data Mining.pptxUnit-V-Introduction to  Data Mining.pptx
Unit-V-Introduction to Data Mining.pptxHarsha Patel
 
Total Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of CannabinoidsTotal Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of CannabinoidsMarkus Roggen
 
Role of Gibberellins, mode of action and external applications.pptx
Role of Gibberellins, mode of action and external applications.pptxRole of Gibberellins, mode of action and external applications.pptx
Role of Gibberellins, mode of action and external applications.pptxjana861314
 
DETECTION OF MUTATION BY CLB METHOD.pptx
DETECTION OF MUTATION BY CLB METHOD.pptxDETECTION OF MUTATION BY CLB METHOD.pptx
DETECTION OF MUTATION BY CLB METHOD.pptx201bo007
 
EGYPTIAN IMPRINT IN SPAIN Lecture by Dr Abeer Zahana
EGYPTIAN IMPRINT IN SPAIN Lecture by Dr Abeer ZahanaEGYPTIAN IMPRINT IN SPAIN Lecture by Dr Abeer Zahana
EGYPTIAN IMPRINT IN SPAIN Lecture by Dr Abeer ZahanaDr.Mahmoud Abbas
 
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
6.2 Pests of Sesame_Identification_Binomics_Dr.UPRPirithiRaju
 
Science (Communication) and Wikipedia - Potentials and Pitfalls
Science (Communication) and Wikipedia - Potentials and PitfallsScience (Communication) and Wikipedia - Potentials and Pitfalls
Science (Communication) and Wikipedia - Potentials and PitfallsDobusch Leonhard
 
Timeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
Timeless Cosmology: Towards a Geometric Origin of Cosmological CorrelationsTimeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
Timeless Cosmology: Towards a Geometric Origin of Cosmological CorrelationsDanielBaumann11
 
Interpreting SDSS extragalactic data in the era of JWST
Interpreting SDSS extragalactic data in the era of JWSTInterpreting SDSS extragalactic data in the era of JWST
Interpreting SDSS extragalactic data in the era of JWSTAlexander F. Mayer
 
Abnormal LFTs rate of deco and NAFLD.pptx
Abnormal LFTs rate of deco and NAFLD.pptxAbnormal LFTs rate of deco and NAFLD.pptx
Abnormal LFTs rate of deco and NAFLD.pptxzeus70441
 
Environmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptxEnvironmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptxpriyankatabhane
 
Advances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of CancerAdvances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of CancerLuis Miguel Chong Chong
 
Production technology of Brinjal -Solanum melongena
Production technology of Brinjal -Solanum melongenaProduction technology of Brinjal -Solanum melongena
Production technology of Brinjal -Solanum melongenajana861314
 

Recently uploaded (20)

Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M⊙ Compa...
Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M⊙ Compa...Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M⊙ Compa...
Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M⊙ Compa...
 
Combining Asynchronous Task Parallelism and Intel SGX for Secure Deep Learning
Combining Asynchronous Task Parallelism and Intel SGX for Secure Deep LearningCombining Asynchronous Task Parallelism and Intel SGX for Secure Deep Learning
Combining Asynchronous Task Parallelism and Intel SGX for Secure Deep Learning
 
Bioenergetics and the role of ATP to drive the beats of life.
Bioenergetics and the role of ATP to drive the beats of life.Bioenergetics and the role of ATP to drive the beats of life.
Bioenergetics and the role of ATP to drive the beats of life.
 
Charateristics of the Angara-A5 spacecraft launched from the Vostochny Cosmod...
Charateristics of the Angara-A5 spacecraft launched from the Vostochny Cosmod...Charateristics of the Angara-A5 spacecraft launched from the Vostochny Cosmod...
Charateristics of the Angara-A5 spacecraft launched from the Vostochny Cosmod...
 
Loudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxLoudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptx
 
Unit-V-Introduction to Data Mining.pptx
Unit-V-Introduction to  Data Mining.pptxUnit-V-Introduction to  Data Mining.pptx
Unit-V-Introduction to Data Mining.pptx
 
Total Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of CannabinoidsTotal Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of Cannabinoids
 
Role of Gibberellins, mode of action and external applications.pptx
Role of Gibberellins, mode of action and external applications.pptxRole of Gibberellins, mode of action and external applications.pptx
Role of Gibberellins, mode of action and external applications.pptx
 
DETECTION OF MUTATION BY CLB METHOD.pptx
DETECTION OF MUTATION BY CLB METHOD.pptxDETECTION OF MUTATION BY CLB METHOD.pptx
DETECTION OF MUTATION BY CLB METHOD.pptx
 
EGYPTIAN IMPRINT IN SPAIN Lecture by Dr Abeer Zahana
EGYPTIAN IMPRINT IN SPAIN Lecture by Dr Abeer ZahanaEGYPTIAN IMPRINT IN SPAIN Lecture by Dr Abeer Zahana
EGYPTIAN IMPRINT IN SPAIN Lecture by Dr Abeer Zahana
 
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
 
Science (Communication) and Wikipedia - Potentials and Pitfalls
Science (Communication) and Wikipedia - Potentials and PitfallsScience (Communication) and Wikipedia - Potentials and Pitfalls
Science (Communication) and Wikipedia - Potentials and Pitfalls
 
Timeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
Timeless Cosmology: Towards a Geometric Origin of Cosmological CorrelationsTimeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
Timeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
 
Interpreting SDSS extragalactic data in the era of JWST
Interpreting SDSS extragalactic data in the era of JWSTInterpreting SDSS extragalactic data in the era of JWST
Interpreting SDSS extragalactic data in the era of JWST
 
Abnormal LFTs rate of deco and NAFLD.pptx
Abnormal LFTs rate of deco and NAFLD.pptxAbnormal LFTs rate of deco and NAFLD.pptx
Abnormal LFTs rate of deco and NAFLD.pptx
 
Introduction Classification Of Alkaloids
Introduction Classification Of AlkaloidsIntroduction Classification Of Alkaloids
Introduction Classification Of Alkaloids
 
Environmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptxEnvironmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptx
 
Advances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of CancerAdvances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of Cancer
 
PLASMODIUM. PPTX
PLASMODIUM. PPTXPLASMODIUM. PPTX
PLASMODIUM. PPTX
 
Production technology of Brinjal -Solanum melongena
Production technology of Brinjal -Solanum melongenaProduction technology of Brinjal -Solanum melongena
Production technology of Brinjal -Solanum melongena
 

Lichens - A general Account

  • 1. LICHENS BY Dr P B MALLIKHARJUNA GFGC YB 25-4-2020
  • 2. LICHENS  Lichens are the most important symbiotic living organisms / plants on the earth.  Theophrastus (371-284 BC), the Father of Botany, to denote the superficial growth on the tree bark, coined the term ‘LICHEN’.  Lichenology is a branch of Botany that deals with the study of Lichens.  Acharius (1798), a Swedish lichenologist, is the Father of Lichenology.  Lichens are one of the largest group of plants consisting about 500 genera and 18000 species included in 9 orders.  A lichen can be defined as “the dual organism with symbiotic (mutualistic) association of a fungus with an alga”.
  • 3.  Mycobiont: is the fungal partner. It is the exhabitant, dominant, colourless, protective and reproductive partner.  Phycobiont:is the algal partner. It is the inhabitant, recessive, coloured autotrophic partner. Although, lichens are the symbiotic associations, the relationship between a fungus and an alga is like a Master and Slave. It is known as “HELOTISM” (Crombie,1885). Fungus is the Master and alga is the Slave
  • 4. Occurrence: Lichens are one of the most widely distributed plants ranging from the polar to the deserts, and aquatic bodies.  Lichens are the dominant vegetation both in the Arctic and Antarctic regions.  They will grow as lithophytes, xerophytes, epiphytes, mesophytes, and hydrophytes.  Some of these are Clandonia rangiferina (Reindeer moss), Peltigera (Aquatic lichen), Gyrophora (White lichen), Graphis, Parmelia, Haematomma, Cora, Dictyonema, etc.  They show great variation in their size, shape, structure, morphology, growth rate and ecology.  In a typical lichen, the fungal partner (the Mycobiont) is the most abundant component, which accounts for 90-95% of the total biomass, whereas the algal partner( Phycobiont) accounts for 5-10%.  The fungal hyphae form a close network resembling a tissue like mass with the algal cells often embedded in it.
  • 5.  Lichens based on their habitat (distribution), external morphology, internal anatomy, and the partners involved (fungal and algal) are classified into several types. 1) Based on their Habitat: There are three types of lichens,viz., a) Saxicoles (which grow on the rocks), b) Corticoles (which grow on the Bark), and c) Terricoles (which grow on the soil).
  • 6. 1) Based on the Habit / Morphology: There are three types of lichens viz., a) Crustose lichens: These are the most common type with thin mat like thalloid plants, firmly attached to the substratum. Ex: Graphis, Haematomma (More common on the barren rocks). The pioneers of the xeorsere type of plant sucession b) Foliose lichens: These are thalloid; flatten leaf like plants attached to the substratum through rhizines. Ex: Parmelia (More common in the tropical forests as corticoles) c) Fruiticose lichens: These are usually a small shrub like vertically or pendulously growing plants. They are common in the temperate and polar regions. Ex: Cladonia
  • 7. 1) Based on the Internal Structure: Lichens may be of a) Homoimerous and b) Heteroimerous In Homoimerous lichens, the fungal hyphae are loosely arranged. Several crustose lichens belongs to this category. In Heteroimerous lichens, the fungal hyphae are thick and compact and thereby surrounding the alga.
  • 8. 1) Based on the Fungal Partner: Lichens can be classified into three types viz., a) Ascolichens, b) Basidiolichens and c) Deuterolichens a) Ascolichens: The fungal partner belongs to the class Ascomycetes. These are the abundant type. Over 98% lichens are Ascolichens. Ex: Parmelia, Graphis. Apothecia, perithecia and pseudothecia are the common fruiting bodies. They may be (Apothecia) or (Perithecia). b) Basidiolichens: The fungal partner belongs to the class Basidiomycetes. They are very less in number (<1%). Some of these are Cora, Corella and DIctyoma. They produce pycnidial cups.
  • 9. 1) Based on the algal partner: Generally, either green alga or the blue-green alga will be the algal partner of lichens. Hence, lichens are a) Chlorophycophyllous lichens and b) Cyanophycophyllous lichens. a) In Chlorophycophyllous lichens, the algal partner is green alga. 80% of lichens contain green alga as a phycobiont. Trebouxia (unicellular) is the most abundant partner followed by Chlorella. b) In Cyanophycophyllous lichens, the algal partner belongs to BGA or cayanobacteria which accounts for ~8%. Some of these are Nostoc, Stigonema, Rivularia, and Gleocapsa. However, Nostoc is the most common partner.
  • 12.
  • 13. REPRODUCTION IN LICHENS:  Both vegetative/asexual reproduction and sexual reproduction are present in Lichens.  The Vegetative Reproduction: takes place very frequently either by the fragmentation process or by the formation of different types of diaspores (having both alga and fungus) such as Soredia and Isidia.  In the vegetative propagation, both the partners are involved and develop into a new daughter Lichen.  Fragmentation is the common mode of vegetation where the fragments are arise either due to the progressive death and decay of older portion or due to the involvement physical factor.
  • 14.  Soredia: These are the asexual/vegetative propagules of Lichens. o These are small, rounded granules or bud-like outgrowth, which develop, in the form of a greyish white or greyish green powder in extensive patches usually over the upper surface or edges of the thalli of many species of Lichens. o It consists of a small group of algal cells surrounded by a few fungal hyphae. o Several soredia are present into a cluster often referred as Sorelia.
  • 15.  Isidia: These are the asexual/vegetative propagules of Lichens. o These are small, conical warts developed on the upper thallus of many Lichens. o An isidium is usually surrounded by cortex and diasporic in composition o Their shape is highly variable among lichens ranging from rod shape to coral-like structure. Ex: Parmelia, Usnea.
  • 16. Sexual Reproduction: Sexual reproduction occurs in many Lichens and in this, only the fungal partner (the mycobiont ) is involved. The role of algal partner is passive or very absent.  The mode of sexual reproduction in lichens maybe spermatogamy.  Ascolichens produce the sex organs namely Spermogonium (male) and Carpogonium (female). After fertilization, they produce the special fruiting bodies such as Apothecium, Perithecium and some times Puesdothecia. Ex: Parmelia  While, the Basidiolichens, produce basispores followed by the formation of the Pycnidia, as the sexual apparatus. After spermatogamy, the sexual fruiting body develops as Basidiocarp like in Agaricus. Ex: Corella.
  • 17. Sexual reproduction in Ascolichens:  Since majority of the lichens are with Ascomycetous fungal partner, it will reproduce sexually by the formation of two different types of sex organs.  The male reproductive structure is Spermogonium and the female reproductive sex organ is Carpogonium.  The spergonium is a flask shaped structure that usually present present upper surface of the thallus. It is with a pore called ostiole, and several muticelluar spmertiophores which produce the uni-nucleate spheroidal sermatia.  The carpogonium is a special cellular filament. It consists of two portions, the lower coiled portion usually called Ascogonium and it is multi-cellular and monokaryotic. It lies deep in the medullary region of the thallus.
  • 18.
  • 19.  The straight upper portion of the carpogonium is called trichogyne and it is multicellular. The component cells are elongated one with the porous cross septa.  The trichogyne receives the spermatia (the male gametes) which in turn penetrates and finally reaches the corpogonium and subject to fertilization resulting a diploid cell called ascus mother cell. This cell proliferates into several asci and whereby the diploid nucleus undergo meiosis and produce haploid ascospores  Likewise, so many filaments arise and protrude above the surface of the thallus and produces the characteristic fruiting bodies viz., 1) Apothecium 2) Perithecium and 3) Pseudothecia with or without stalk.
  • 21. 1) Apothecium: is a major type of sexual fruiting body of Ascolichens.  It is generally round and cup-shaped structure.  Their colour is highly variable ranging from reddish to black colour.  In some lichens, the apothecia contain only the mycobiont but the phycobiont is absent. Ex: Cladonia.  However, in majority of the lichens, the apothecia possess both the partners. Ex: Parmelia. Apothecium structure: Apothecium is lined with palisade-like layer cells called Hymenium.  The Hymenium consists of a series of elongated cells – the asci, intermixed with sterile hyphae – the paraphyses.  Each ascus usually contains eight ascospores (bi-celled). The liberated ascospores liberated, if come in contact with suitable alga, produce the new daughter thallus. Otherwise they perish.
  • 22. 1) Perithecium: This is another sexual fruiting body of the Ascolichens.  It is much smaller than the apothecium and flask shaped structure and appears as a small dot on the surface of the thallus.  The dark coloured wall bound it.  The cavity is lined with asci.  The paraphyses are few in number or totally absent.  It is embedded in the elevations of the thallus on the upper side.  It opens through a small pore called an Ostiole.
  • 23. ECOLOGICAL ROLE OF LICHENS 1) Lichens are serving as the indicators of Air pollution. Especially they are very sensitive to the NO2 and SO2 gases. 2) They involve in the soil formation on the rocks called biological weathering. 3) They are the first/pioneer colonizers on a barren rock in the establishment of ecological plant succession. 4) Some lichens may be used as tools in order to determine the age of the rocks and the past events occurred called Lichenometry. ECONOMIC IMPORTANCE OF LICHENS  Since lichens are rich with secondary metabolites like alkaloids, oils and other substances, lichens are extensively used in medicine, besides serving as food and fodder to man and animals. Further, several acids, dyes (orecin, litmus) are extracted. Also using in perfume and dhoop industries