Lichen on old wooden fencepost

[Bruce Williams]

Stony Stratford, Bucks. Fencepost facing west.

Help with identification appreciated.



Bruce

[JennyS]

Hi Bruce,

With crustose ones it can help with identification if you spot test to see what the K and C reactions are:
The British Lichen Society - Chemicals for Lichen Identification

[AlanS]

I am puzzled.

If it was more greyish, I would say Lecanora conizaeoides - it has the characteristic, sorediate margins to the apothecia that are typical of the species, and the cracked, sorediate surface and somewhat sunken apothecia are all correct,
BUT
I think it is the wrong colour and L. conizaeoides, formerly an abundant urban lichen in areas of sulphur dioxide pollution, has now become scarce.

As Jenny has said, chemical tests are needed, in this case especially with paraphenylenediamine, which gives a red reaction with L. conizaeoides (but is carcenogenic!).

It reminds me that I have a green lichen that I think is this species awaiting testing - not sure when I shall do it, but it may give me the extra experience to come back to this thread. Sometime.

AlanS

[AlanS]

Actually, looking at the photograph again, I note that the green colour may be from free-living algae on the surface (escapees? like sheep that have got through the fence?).

Consequently, I am more certain (but not 100%) that this is Lecanora conizaeoides.

It still needs chemical tests I think.

Alan

[Bruce Williams]

Thanks for you help with this one Alan. I'll check close by and see if there are any other colonies - if there are I'll photograph them.

Bruce