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PRESENTED BY : AQIL QURESHI
UNIVERSITY OF EDUCATION TOWNSHIP
CAMPUS

? Introduction
? Structure of Lichens
? Forms of Lichens
? Classification of Lichens
? Species and Common Naming of Lichens
? Vegetative Reproduction
? Asexual and Sexual Reproduction
? Economic Importance of Lichens

? Order : Lechano Rales
? Kingdom : Fungi
? Genus : Lichens
? The intimate symbiotic association of fungi and algae is
called lichens.
? The algae of lichens mostly belong to chlorophyta and
cynobacteria.
? Lichens are abundant growing on bark, leaves and
mosses.
? The fungus is called mycobiont. The
photosynthesizing organism is called a photobiont.

? The part of lichen that is not involved in reproduction is
called Thallus.
? Thallus is composed of following parts:
? Upper Cortex
? Algal Zone
? Medulla
? Lower Cortex
? Upper Cortex: Cortex is a protective skin of densely
packed fungal filaments. Upper cortex present on the
top side.

? Algal Zone: These are often enclosing algae within
complex fungal tissues.

? Medulla: It is the central part of the thallus. It forms
the main part of thallus. These are the conductiong
cells.

? Medulla: It is the central part of the thallus. It forms
the main part of thallus. These are the conductiong
cells.
? Lower Cortex: It is present below the medulla. It is a
narrow layer of compactly arranged hyphae.

? The lichens are divided into three groups on the basis
of thallus.
? Crustose Lichens:The thallus from crust like structure.
It is closely adhere to the substrate.
? Example: Graphics
? Foliose Lichens: In this case, thallus has leaf like
lobes. They are free from the substrate.
? Example: Physcia, Permellia.
? Fructicose Lichens: The thallus are cylindrical ribbon
like and branched.
? Example: Cladonia, Usnea

? There are two groups of lichens:
? Ascolichens: In this case, lichens belong to
Ascomycota. Majority of the lichens belongs to this
group.
? Basidiolichens: In this case, lichens belong to
Basidomycota.

? There are about 20,000 known species of lichens.
? Some lichens have lost the ability to reproduce
sexually. But they are still taken as specie.
? Common names for lichens may contain the word moss
like Reindeer moss and Iceland moss.

? Vegetative reproduction occurs by different methods:
? Fragmentation: It is most effective way of
reproduction.
? It is found in foliose and fruticose lichens.
? Mechanical stress or death of some cells breaks the
thallus into fragments.
? Each fragment has growing areas.
? There growing areas grow to form new thallus.
? Isidia:These are small papilla like outgrowths.
? These are present on the upper surface of thallus.

? Each isidium is composed of algal cells and fungal
hyphae.
? Isidia detach from the body. Isidia are found in
Permellia etc.
? Soredia: Soredia are small bud like outgrowths formed
on the surface of thallus.
? Soredia are composed of many algal cells with few
fungal hyphae.

? Cephalodia: They are external or internal gall like
outgrowths.
? They are dark in colour.
? They consist of fungal hyphae enclosed in algal cells.

? Asexual reproduction takes place by pycnidiospores,
conidia oidia formation.
? In some cases, hyphae break down into small pieces
known as oidia.
? While pycniospores are produced within the flask
shaped structures known as pycnidia.
? Sexual reproduction is oogamous, Ascogonium and
spermatia are formed.
? Oogamous characterized by fusion of a small actively
motile male gamete and a large immobile female
gamete.

? Ascogonium
? The female sex organ in ascomycetous fungi.
? The hyphae, in fungi of the Ascomycota, that grow
from the ascogonium after it has fused with the
antheridium.
? Spermatia
? A nonmotile male gamete, as in red algae and certain
fungi.
? Colorless cell of certain fungi and lichens, developed
within spermagonia.

? Role in nitrogen fixation
? Food
? Biodegradation
? As dyes
? Antibiotic metabolites
? Traditional medicine

? Role in Nitogen Fixation: Cynobacteria are involved
in nitrogen fixation.This nitrogen increases the fertility
of soil.
? Food: some used as a staple food.It was cooked as a
bread, pudding, soup, or salad.
? Biodegradation:Lichens can degrade polyester resins.
? As dyes: Many lichens produce secondary compounds
and pigments.

? Antibiotic Metabolites: Lichens produce metabolites.
These are useful in the medical community.
? A few are associated to antiseptic.
? Traditional Medicine: Lichens are also used in
nonscientific traditional medicine practices of many
cultures.

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Lichens

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