Like a lichen

Xanthoria polycarpa

I find Lichens one of the most awe-inspiring aspects of nature. They actually consist of both a fungus and an alga (or sometimes a cyanobacterium) which live together, producing an amazing array of life forms.  The shape of most lichens is completely different from that of the components.

The relationship is usually described as symbiosis: the fungus provides protection, anchorage and some moisture collection, while the alga provides carbohydrates from photosynthesis. Living together they are able to extend their range and both benefit.

There are possibly around 2000 different lichens in the UK and a sunny day in autumn or winter is a great time to see them (especially those growing on trees as the leaves have fallen.)

Evernia prunastri

 Many lichens are sensitive to air pollutants such as nitrogen and sulphur dioxide, so generally, the better the air quality, the better the range of lichens.  I certainly think of the Caledonian Pine forests of the Cairngorms when I think of lichens hanging off trees but even here in the South east of England we have a fantastic range and there is no way that I could identify all those we have found today. 

I think it is the diversity that I love so much (apart from the unlikelihood of them existing in the first place, let alone reproducing!)  They can spread vegetatively but the fungal component can also produce spores which would then have to re-associate with the alga or cyanobacterium.

So have a look next time you are out and marvel at the variety of lichens in your area.