Lichenology - Characteristics of Lichen

Definition: Lichens are slow growing, long living organism formed by the symbiotic association between algae and fungi that form a unique morphology distinct from both partner.
•The fungal partner is called mycobiont
•The algal partner is called phycobiont
Theophrastus coined the term ‘lichen’ for superficial growth on the bark of olive tree.
About 500 genera and over 15000 species are known
Lichen
General characters
  • Grows in areas where either fungi or algae could not survive alone: rocks, cement, rooftops, trees, and newly exposed soil.
  • world wide distribution and can grow in the extremes of temperature and heat
  • Grows very slowly, secreting acids that break down rocks.
  • Accumulate nutrients needed for plant growth.
  • Sensitive to air pollution especially sulphur dioxide therefore absent in and around large cities. Hence lichens are often considered as indicators of air purity
  • Thallophytic plant body, irregularly shaped and often deeply pigmented
  • Colouration is  due to the pigmentation of the alga partner
  • The algal partner belongs to either blue green algae like Nostoc, Stigonema, Rivualria or green algae like Trebouxia
  • The fungal partner mainly belongs to ascomycetes apart from basidiomyctes and rarely deuteromycetes

Classification of Lichen
Reproduction in Lichen
Reproduction in Lichen Learn more: Classification of Lichen, Nature of association of Lichen, Structure of Heteromerous thallus in Lichen
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