200 lichens are found locally |
However what surprised me more was the fact that none of them could tell me what lichen is.
This was surprising because lichens are common everywhere being able to grow in the most unusual places including bare rock and walls even in urban areas. About 200 lichens have been recorded in the Maltese islands but I am sure that with some effort more unrecorded species can be found.
Lichens are unusual because each species is
made up of two organisms, a fungus and an alga, living intimately together.
This gives lichens the ability to survive under harsh conditions where no other
organism can survive.
In some cases the fungus and alga which
make up a lichen can be found living separately in nature but in many cases the
two organisms have become so dependent on each other that one can not survive
without the other.
Lichens do not have leaves or roots and
absorb nutrients directly through their surface. This leaves them susceptible
to air pollutants which accumulate in their body without being eliminated.
Lichens can tolerate different concentrations of pollutants with some species dying at lower levels than others. This makes lichens excellent biomonitors and many species are used to indicate levels of environmental pollutants.
Many species of lichen are eaten especially in
times of famine despite of the fact that they can be difficult to digest. Many
species also contain mildly toxic compounds although few species are poisonous. Lichens can tolerate different concentrations of pollutants with some species dying at lower levels than others. This makes lichens excellent biomonitors and many species are used to indicate levels of environmental pollutants.
Some species are used to produce dyes including the pH indicator litmus.
This article was published in The Times on 07.03.2012
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