Question

A location with a luxuriant growth of lichens on the trees indicates that the:

• A. Trees are very healthy
• B. Trees are heavily infested
• C. Location is highly polluted
• D. Location is not polluted

Answer 1

The correct option is D Location is not polluted

Lichens are plants that grow in exposed places such as rocks or tree bark. Lichens are regarded as pollution indicators. They are sensitive to sulphur dioxide. If the air is very badly polluted with sulphur dioxide there may be no lichens present, just green algae may be found but if the air is clean, shrubby, hairy and leafy lichens become abundant, which indicates that the location is not polluted.