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Lichen with white fimbriate edge

Observed: 1st January 2013 By: pf339
S159 Neighbourhood Nature - course complete
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Lichen with white fimbriate edge

Grey-green, powdery, crustose lichen on siliceous sandstone gravestone. Thallus K+ yellow. Outer edge consists of a white fimbriate prothallus. Possibly Haematomma ochroleucum.


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Species interactions

No interactions present.


pf339's picture


Thanks for help with this identification. The structure of the fimbriate border was a real surprise for me.

AlanS's picture

var. porphyrium

I thought about this for a day or so before agreeing, as the soredia are rather green and I wasn't sure about that. But the 'Lichens of GB&I' allows var. porphyrium to be greenish, and the cited, 'approved' photograph in van Herk & Aptroot ('Veldgids Korstmossen') is a good match. Your photo shows the fimbriate margin very well.

Interestingly, this variety grows in great sheets on cliff-faces on the Isle of Muck, seen on the BLS meeting last summer, and to my eyes it had a distinctly yellow tint and I argued hard with two leading Scots lichenologists that it ought to be var. ochroleucum, but like your photo, it was just an effect of dampness. Looking at my photographs subsequently, I see they were right. First time I had seen it fertile - I shall put the photos on my site sometime in the next decade or so. The apothecia are more easily overlooked than I had expected, but attractive under a lens.