Leaf-like, grey/green colour on tree trunk by side of the road.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
When I did Neighbourhood Nature autumn 2009 there was a good explanation of scientific names on page 4 of the course book.
For the course if I remember you only needed to identify the growth as Crustose, Foliose or Fruticose but when trying to identify the species of lichen this is only the first step. You have several species in your photo, there are excellent sites to refer to mentioned on the Fungi and Lichens Group page of iSpot, I recommend http://www.lichens.lastdragon.org/ and http://www.irishlichens.ie/index.html
Good Luck with the course!
Certificate in Contemporary Science (Open)
Lat/Lng: 51.5, -2.6
OS grid ref: ST5978