Write a short note on Lichens.

(N/A) $\rightarrow$ Lichens are symbiotic associations,i.e.,mutually useful associations between algae and fungi.
$\rightarrow$ The algal component is known as the phycobiont and the fungal component as the mycobiont; they are autotrophic and heterotrophic,respectively.
$\rightarrow$ Algae prepare food for fungi,and fungi provide shelter and absorb mineral nutrients and water for their partner.
$\rightarrow$ Their association is so close that if one saw a lichen in nature,one would never imagine that they had two different organisms within them.
$\rightarrow$ Lichens are very good pollution indicators; they do not grow in polluted areas.