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Long-living lichen and other tongue twisters

Lichen on Stone


We all see a lot of lichens, but we pay them little attention. They are not endowed with classical beauty and yet their absence can make places distinctly less attractive. What we think of as a typical English country church and yard might look closer to an unsightly modern development than we cared for, if it were not for the long, slow, determined influence of the lichens. Village churchyards form very good habitats for lichens: the choice of stone, the fresh air and the general lack of decorating or other surface tinkering makes for a happy lichen home.

It is their fussiness that can help us deduce direction as one type of lichen is unlikely to favour two sides of anything equally, whether it is a rock, tree or mound of earth. Some find their heaven on the shaded north side of churches, others seek paradise on the west side of rocks as they soak in the moisture from the rain bearing winds.

A few facts are well-understood and known about lichens, that they are symbiotic for example and they abhor pollution (they are used as environment indicators and are rare in town centres). In a spirit of lichen celebration, I thought that I would list a few things that are less well known:

1) Lichens have a case as the oldest living things, some having been around 9000 years.
2) Although sensitive to pollution, especially sulphur dioxide, lichens have a high tolerance for ionising radiation, significantly higher than humans. This is not all good news however. The lichens can absorb radioactive material, the reindeer then consume the lichens, the Eskimos then eat the reindeer…
3) The litmus paper that we know and love from our school chemistry days is able to change colour thanks to the lichens that are used to make it.

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