Churchyard Nature Note with Andrew Tompsett
November 09
Lichens – a whole world of mini-plants
Cornwall is well known for its clean air
and this encourages the growth of lichens.
Some of the best places to see them are
in ancient churchyards such as ours at
St Illogan.
Unless you are on Bodmin Moor or in
West Penwith where the trailing webs
of lichens on the stunted trees are very obvious,we may overlook the smaller
but hugely variable family of primitive plants, which are to be seen everywhere
on undisturbed trees and stonework.
Lichens are a mutual ‘living together’ (or symbiosis) ofsimple plants (algae) and fungi. The fungus provides the anchorage and soaks upmoisture like a sponge whilst the alga has chlorophyll, powered by sunlight, to manufacture food for them
both. Most grow best on damper, shadier surfacessuch as the north side of gravestones or trees.Lichens do
not flower but produce spores which establish themselves on suitable
unpolluted surfaces or
through broken fragments resettling. They
are some of the earliest settlers on bare
hard surfaces. We also see them as a guide to thecleanliness of the air we breathe.
Growth of lichens is often exceedingly
slow. You may have noticed that there are round patches on a gravestone near the main gate which appear almost
unchanged for years. For this reason it
is important to see that these ancient growths are preserved since some of
them may be 50 or more years old.
In our churchyard, look closely and you
can easily see severaldifferent kinds of lichens on the gravestones. One develops small bushy tufts, another forms creeping, flat, folded-leafy patches, others appear
as thin crusts or even a dry powder. Colours range from white through grey-green to orangeyellow or black. A similar range can be found on
the older trees where they do no harm and somecoloured lichens can even be used to produce natural dyes.
Some churchyards, for ease maintenance and safety, have laid down gravestones
or movedthem to the boundaries. This has been criticised by lichenologists because the ancient lichens are then killed by being covered or exposed to too much sunshine which dries them out. Extensive
clearance may destroy many ancient or rare lichens.
For the same reason it is wrong to clean gravestones excessively and chemicals
should not be applied to them. Lichens are as old as the trees - they are just smaller! Do take a moment to look at them and see how many different kinds you can find.