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Rusty red crustose lichen. - (ID request).

Posted: Fri Jun 01, 2018 6:18 pm
by Lancashire Lad
Hi all,

Anyone got any ideas as to what this rusty red lichen might be?

34 Rhizocarpon geographicum etc. - Lichens.jpg

I'm pretty sure that the yellow one it's with is Rhizocarpon geographicum, but the red one has me stumped.

Several suspects in Frank Dobson's book, but I wouldn't be confident naming this as any one of them.

Found mid-May, on numerous loose boulders at an altitude of about 2900ft., near the summit of Scafell in the Lake District.


Re: Rusty red crustose lichen. - (ID request).

Posted: Mon Jun 11, 2018 5:54 am
by Chris Johnson
Hi Mike

I can only think of Xanthoria elegans, a foliose species of higher altitudes. A variable species both in form and colour.

Regards, Chris

Re: Rusty red crustose lichen. - (ID request).

Posted: Mon Jun 11, 2018 10:53 am
by Paul Cannon
The green lichen is certainly Rhizocarpon geographicum. The orange stuff is the alga Trentepohlia, species of which can be free-living as well as farmed by fungi in lichen associations. Colonies can be frequently encountered in damp or shady conditions, on rocks or trees - you often see it on willow trunks, for example. So, you have half a lichen, by some interpretations...

Re: Rusty red crustose lichen. - (ID request).

Posted: Mon Jun 11, 2018 3:44 pm
by Lancashire Lad
Thanks both.


Xanthoria elegans was one of several suspects that I'd looked at, but this, like the others I'd looked at seemed to be just too far away, and not showing any distinct characteristics to enable me to plump for a particular species.
With Paul's reply - now I know why! :shock:

Many thanks for solving this mystery for me. - I would never have thought to consider something like Trentepohlia!
I've encountered that many times. Always, (to my knowledge when I've recognised it), in shady woodland habitats.

This find though, was on large boulders on an otherwise bare mountainside - exposed to full sunlight for most of the day in a situation that would, as a result, be very dry. Only on rainy days or possibly at times when mountain mists are evident, would this type of "habitat" get any water.

I've seen the exact same stuff before, in very similar exposed, dry, bouldery habitat on Lake District fell-tops (Crinkle Crags and Sergeant Man come to mind). - but this time, curiosity got the better of me. - I hadn't previously tried to get an ID.