Lichens are slow-growing, long-living organisms formed from the symbiotic association of algae (phycobiont) and fungi (mycobiont). They are classified by their fungal component and external form, with three main types: crustose, foliose, and fruticose. Lichens have various economic uses, including food and fodder for animals, and contain compounds like usnic acid that have medicinal properties.

1. LICHENS
Deparment Of Botany
Preapared by
Dr. P. B.Cholke
(Assistant Professor in Botany)
Pune District Education Association’s
Anantrao Pawar College ,Pirangut,
Tal-Mulshi, Dist-Pune- 412115

2. LICHENS
• The lichens are slow growing, long living organisms.
• Theophrastus was first to use the word lichen.
• Lichens are formed by close association of two
different partners,
• A) Phycobiont or photobiont: The algal component
of lichens is called phycobiont.
• It mostly belong to Chlorophyceae(green algae)
Or cyanobacteria ( blue green algae)
• B) Mycobiont: The fungal component of the lichens
is called mycobiont. It belongs to ascomycetes and
rearly Basidomycetes or Deuteromycetes.

3. • Habitat of lichens:
• They grow on tree trunks, decaying logs, and
on soil.
• They are found in extreme climatic conditions
such as on dry exposed rocks.
• They are sensitive to air pollution and do not
grow near cities.
• Body is thalloid with greenish or bluish green
in color.

4. • Classification of lichens:
• A) On the basis of Fungal componenta lichens
are divided in to three categories.
• I) Ascolichene: Fungal partner belongs to
Ascomyctes.
• II) Basidiolichens: Fungal partner belongs to
Basidiomycetes.
• III) Deuterolichens: Fungal partner belongs to
Deuteromycetes. These are sterile lichens
producing no spores.

5. • B) On the basis of external form ( Thallus
organization) lichens are of three types:
• a) Crustose lichens:
• These are thin and flat lichens occuring on
crust on the bark of rock.
• Examples: Graphis, Lecanora, Haematomma
etc.

6. • b) Foliose lichens:
• These are lobed and dorsiventrally flattened,
leafy lichens.
• They are attached to sumstratum by hairy
rhizoids called rhizines.
• Examples:
• Parmelia, Collema, Peltigera.

7. • C) Fruticose lichens:
• Commonly called as shruby lichens.
• They have cylindrical, branched and erect
thallus.
• They remain attached to the substratum by
basal mucilagenous disc.
• Examples: Cladonia, Usnea, Alectoria.

8. • Reproduction: Lichens generaly reproduce by
vegetative, asexual, and sexual methods.

9. Economic Importance of lichens
• 1. Lichens as a food:
• Permelia is used in curry powder as well as in
makingchocolates and pestries.
• 2. Lichens used as Fodder:
• Lichens form favorite food for reindeers and
cattles.
• Cladonia, citraria, Evernia Permelia used as
fodder.

10. • 3. Medicinal uses:
• Usnic acid obtained from Usnea and Cladinia.
Used as antibiotic against gram positive
bacteria.
• 4. Soil formation