Lichen

Today's the day …………………. to google
 
This is the strange and wonderful world of lichens - growing on a bough of an old apple tree.
 
I'm afraid, rather like the strange and wonderful world of fungi, it is not an area of any sort of personal expertise.  So because I think I really should know a bit more, here are a few facts about lichen that Mr Google prepared earlier: 
 
A lichen is not a single organism, but the result of a partnership (mutualistic symbiosis) between a fungus and an alga or cyanobacteria.
 
Because lichens enable algae to live, they also provide a means to convert carbon dioxide in the atmosphere through photosynthesis into oxygen, which we all need to survive.
 
Lichens can be used as air pollution indicators, especially of the concentration of suphur dioxide in the atmosphere.
 
Lichen grows on all sides of a tree, but often prefers the side facing away from the sun.
 
For the most part, lichens growing on trees is a good thing, not harmful to the trees. However, they do occasionally indicate a lack of vigour in the affected plant.  Weak or dying trees may have a lot of lichens, since the trees' decline creates conditions of light and moisture that encourage lichens to grow
 
So now you know as much as I do ………………..