Xanthoria parietina and Physcia adscendens?

[diatom dave]

This is my first reasonably confident attempt at identification. I think its Xanthoria parietina and the little one in the middle with the dark cilia I think is Physcia adscendens. I've included a magnified portion just showing P. adscendens. Am I right? Probably not.

[AlanS]

Originally Posted by diatom dave

This is my first reasonably confident attempt at identification. I think its Xanthoria parietina and the little one in the middle with the dark cilia I think is Physcia adscendens. I've included a magnified portion just showing P. adscendens. Am I right? Probably not.

Hi Dave, you are wrong.

With your "Probably not" comment, that is - your identifications are correct! The Physcia amidst your Xanthoria does look like P. adscendens, with its hooded lobe tips.

Did you also notice that to the right of the Xanthoria you have Physcia tenella, with its "lip-shaped" lobe tips?

All three species commonly grow together of course - indicators of ammonium & nitrate deposition from traffic, agrochemicals etc. - now looking like a major threat to many of our species, even in those remote, rural areas that escaped sulphur dioxide pollution in past decades.

Alan

[diatom dave]

Thanks again Allan. Interestingly only yards from this tree was a hawthorn with, I think, a species of the genus Usnea growing on it. I haven't had the time to investigate further but once I 've got a photo and had the time to have a go at identification I'll post it. I suppose the Xanthoria etc. will happily grow where there is low nitrates etc. it's just that they can tolerate them much better than the Usnea spp.