"Neil Jones" wrote in message
m...
Andy Hall wrote in message
. ..

That's no real issue and can easily be removed. I quite like to see
a certain amount of lichens on roof tiles. It makes them look more
interesting.....


Apparently lichens only grow in places of low atmospheric pollution,
so it's a good indicator of air quality, as well as any aesthetic
benefit.

but is the same true about moss? In fact, are moss and lichen synonymous?
I know that lichens are rarer than they once were.

I'm sitting working looking at the roof of the house opposite, and this is
liberally covered in mosses. This is sunny Twickenham, not that far out of
London and close to the Heathrow flightpaths and one of London's arterial
road, so whereas this might not be an area particularly high in atmospheric
pollution it certainly isn't the cleanest environment.

I've taken the liberty of crossposting this to uk.rec.gardning, in the hope
that one of their knowledgeable netizens may be able to throw some light on
the question.



--
Richard Sampson

email me at
richard at olifant d-ot co do-t uk