Some more pictures of the lichen on a rock by a 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.
This lichen seems to be Xanthoria parientina.
These photographs seem to be from a different lichen to that in your other post titled 'Xanthoria calcicola' - these show abundant apothecia (fruiting discs) but no isidia....
Even when its fertile isidia should be present on the thallus of X. calcicola.
Thanks for the comments, can the 2 species grow together on the same rock?
Just found this on-line
This shows both for X. calcicola, perhaps X. parietina does not have any insidia and X. calicola can have both apothecia and insidia
Yes, they can be found together - X. parietina never has isidia and only has apothecia but sometimes X. calicola can have both.
The photo in your link shows this well with the apothecia at the top of the photo and isidia below, nearer the centre of the thallus.
They can be very, very puzzling as they can be very variable, many species are very similar and sometimes the only way to identify them is by means of chemical spot tests, microscopy (looking at the spores) or Thin layer chromatography (TLC).
It is often not possible (and unwise to try) to identify lichens from photographs alone.
An interesting topic, I've put a new photo on which shows both species, it seems they have merged into one another, this will help others with ID
Thanks again for your help
Lat/Lng: 52.2, -3.4
OS grid ref: SO0560