About lichen, its definition, basic growth form with figure, on the basis of substrate growth form, importance

1. General account of Lichens
Dr. Shobha Rawat
(MSc Botany, Ph. D.)
Botany Department
Assistant Professor (T. P.)
Department of Botany
Soban Singh Jeena University, Almora

2. What are Lichens?
Lichens are fungi that live in intimate
symbiotic association with green algae or cyanobacteria.
x10

3. Lichen is a composite organism that is
formed by a symbiotic relationship
between algae or cyanobacteria and some
fungi species.
or
Any complex organism of the group
Lichens, composed of a fungus in
symbiotic union with an alga and having a
greenish, gray, yellow, brown, or blackish
thallus that grows in leaflike, crustlike, or
branching forms on rocks, trees.
Example: Lecanora, Parmelia,
Flavoparmelia
•Lichen Definition

4.  The peculiar structure and unique physiology of lichens
enable them to colonize on a number of substrates in
varied climatic condition.
 Lichens have an ability that they can grow on a substrate
which is not colonized by other group of plant, such as
glass, bone, man made artifacts and barren rocks.
 Lichen grow in extreme condition like the Arctic, Tundra,
hot spot, hot dry desert, rocky coasts toxic heaps roof,
roof bare rocks, walls, exposed soil surface.
 Lichen occur from high alpine elevation to sea level the
ability to grow any surface.
 More than 50% of the lichen substances have antibiotic
activity.
INTRODUCTION

5. India has a rich diversity of lichens
represented by more than 2000 species,
(Awasthi; 2000). Which is about 10% of
the total 20000 species known from the
world. The lichens are common to
abundant in temperate and alpine regions
of the Himalayas and hilly region of
peninsular India.
•DISTRIBUTION

6. About Lichens
Symbiotic
Association
Algae
Fungi
Photobiont
Mycobiont
800
Total Known
Secondary
metabolites
50
Common
with other
Group of
Plants
700
Unique not
known in
any other
Group of
Plants
Lichen produce about 800 unique type of chemicals of which
only few are common with other group of plants and mostly
more than 700 are unique only known from lichens.

7. More than 700 lichen metabolites are
known from the lichens out of which only
50 are common with other group of plants,
650 are unique to lichens and not
produced by any other plant group.
Lichen metabolites exert a wide variety of
biological action including antibiotic,
antimicrobial, antibacterial, antiviral, anti-
inflammatory, analgesic, antipyretic,
atiprolifertic and cytotoxic effect
•Secondary Metabolites

8. GROWTH FORMS
Fruticose
Crustose Foliose

9. •1. Crustose - Thallus having crust like, growing tight
against the substrate.
•Example : Acarospora, Lecanora
•2. Foliose - Thallus having leaf and lobe like, loosely
attached with substrate through rhizoids, with flat sheets
of tissue not tightly bound.
•Example : Parmelia, Flavoparmelia
•3. Fruticose - Thallus having ribbon, thread like,
free-standing branching tubes, sometime perpendiculate
attached with substratum.
•Example :Usnea, Cladonia
•Lichens occur in three basic growth forms

10. TYPES OF LICHENS
ON THE BASIS OF
SUBSTRATUM
• Corticolous
• Ramicolous
• Saxicolous
• Terricolous
• Foliicolous
• Muscicolous

11. On the basis of substratum lichens may be grouped into
 Corticolous lichens: If growing over bark of tree, cortex or
wood. Example : Heterodermia
 Saxicolous lichens: Growing on rock boulder. Example :
Acarospora
 Terricolous lichens: When growing on soil. Example :
Heterodermia
 Foliicolous lichens: Grow on perrenial leaves. Example :
Strigula
 Muscicolous lichens: If growing lichen on mosses.
Example : Peltigera
 Ramicolous lichens: Some lichens only grow on the twigs
of the tree, is called ramicolous lichens. Example :
Ramalina
TYPES OF LICHENS ON THE BASIS OF SUBSTRATUM

12. ◊ Food for man
◊ Food for animals
◊ Medicines
◊ Dyes
◊ In perfumery
◊ Pioneer of
colonization
◊ Indicators of air
pollution
ECONOMIC IMPORTANCE OF LICHENS

13. Forest area with dominant lichens

14. Forest area with dominant lichens