Cup lichen

I have started a major restoration of my greenhouse.  It is 25 years old and made of western red cedar but is in poor repair in some parts and is in danger of falling down.  It has become home to several sorts of moss and lichen, including this cup lichen, which I think is a Cladonia species.

I can just about remember from A-level biology almost 50 years ago that a lichen is a symbiosis between a fungus and a green alga.  I read on the website British Lichens that there are around 1800 species in the UK - slightly more than the number of species of vascular plants.

The goblet-like structures are podetia which are growing out of the main body of the lichen - the thallus.  The podetia support the spore-producing apothecia involved in sexual reproduction.  The spores contain only the fungus part of the organism and when they germinate they have to relichenise by acquiring the right green alga.  While taking the pictures above I remembered photos of a similar lichen I saw on top of Mam Tor in Derbyshire in spring, showing its red spore-producing apothecia.

By the time I have finished the greenhouse it will look like new and the lichens and mosses will have to find somewhere else to live.