Why are lichens called bio-indicators?
Lichens are called bio indicators as they indicate the environmental pollution through their gradual extinction in those regions where there is excessive pollution especially the air pollution.
How does lichens reproduce asexually?
Lichens reproduce asexually by:
1) Fragmentation
2)By soredia (small rounded bud like outgrowths developed in the form of greyish white or green powder on the upper surface of thallus.
3)By isidia (small papillate outgrowths developed on the thallus)