ID help for lichen on twigs please

[jaybie]

I haven't really paid much attention to these before but decided to have a closer look - quite fascinating forms I discovered but I suppose you already know that

First one on Hawthorn ..



Second one on Elder ..



I think they must be quite common as they were in abundance so to speak.

Thanks, JohnB

[diatom dave]

Hi JohnB,
I'm pretty sure that your first photo is of Xanthoria parietina whilst the second one is probably Physcia adscendens. Both are common on twigs and are often found together. Please don't take this as definite cos I'm a newbie at identifying lichens but I'm fairly sure.. Cheers, Diatom Dave.

[jaybie]

Thanks Dave - I can look for a bit more information on those now.

[AlanS]

Originally Posted by diatom dave

Hi JohnB,
I'm pretty sure that your first photo is of Xanthoria parietina whilst the second one is probably Physcia adscendens. Both are common on twigs and are often found together. Please don't take this as definite cos I'm a newbie at identifying lichens but I'm fairly sure.. Cheers, Diatom Dave.

Agree photo 1 is Xanthoria parietina, and the pure grey lichen with marginal cilia in photo 2 is a Physcia and quite possibly P. adscendens, though immature and not very typical.
However, the yellow (and grey tinged with yellow) lichen in photo 2 looks like young Xanthoria polycarpa.

I am constantly warning people not to confuse X. polycarpa with young X. parietina and I have watched reasonably competent lichenologists make the mistake, but I think this is the real thing.

The sad thing is that this lichen community is now all that one can find on trees in many areas, because of the amount of nitrates/ammonia in the atmosphere from agrochemicals and car exhausts. It is like the widespread loss of lichens that occurred as a result of sulphur dioxide pollution, but more insidious and ultimately perhaps more devastating.

Elder does, of course, have nitrogen-rich bark in any case.

Alan