The Trouble with Lichen

"Have you noticed that some houses are going green?" said the Long Suffering Husband.
"Well, that's the trouble with lichen," I said, "It loves the wet and so we now have the perfect conditions for it to multiply and take over the world. Before you know it it will be swapping itself for people's children and we won't even notice because they'll be so perfect."
"What are you talking about," he asked, whilst flipping through the telephone directory looking for 'men in white coats.'

The truth is, I wasn't really sure.  I had a vague recollection of reading a book called The Trouble with Lichen as a teenager and I thought it was about some kind of alien life form that then took over the world.  It was, in fact, a book by John Wyndham, which I have confused with another of his books, The Midwich Cuckoos. The main thing I remember about the book was the title and how smug I felt that I knew that Lichen wasn't pronounced phonetically but had a hard k sound in the middle.

There does seem to be an awful lot of lichen around at the moment though, so I started to wonder what it was all about if it wasn't an alien life form trying to take over our newly wet world.  I was stunned to find that there is a British Lichen Society and have spent a very interesting morning reading about this fascinating thing.

Lichen isn't just one organism but a combination of two or more, including a fungus.  They are a sensitive species and rather than taking over human life seem to indicate conditions in which we can thrive.  They need oxygen, just as we do and only grow in  clean air.  John Wyndham must have known all this because in his book, a female biochemist discovered a rare strain of lichen that stopped the ageing process, causing people to live to 200 - 300 years old.  Maybe it was when I read that book that I decided I didn't want to live forever. It is nice to know that I live in an area with clean air.