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Black foliose lichen

Observed: 2nd April 2013 By: pf339
S159 Neighbourhood Nature - course complete
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Black foliose lichen i
Black foliose lichen ii

Black foliose lichen patches, looks as if remaining from large rosettes, growing on vertical limestone face. Lobes thin and ragged in places. Some isidia on lobes - visible in right hand picture (close up of part of lower patches in left hand picture). Possibly Collema cristatum.


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Species interactions

No interactions present.


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Thanks for help with identification of this Collema sp.

synan's picture

Alternative ID

Collema spp. vary horrendously in their appearance and my understanding of them is still at an early stage, but I think this is C. fuscovirens. The lobes are more rounded than I have seen in C. cristatum (described as having "dentate or small-lobulate, sinuose margins) and I find the presence of isidia a bit offputting, despite accounts that C. cristatum sometimes has a few (putting aside var. marginale, which is described as often having isidia - not surprisingly, at the margins).

I think your photos are comparable to these from the British Lichens site:

Collema fuscovirens
Close up

Evidence of a pustulate lobe surface should confirm C. fuscovirens.

My encounters with what I am calling C. cristatum have mostly been in the same area (Malham, Clapham, Stainforth etc) and I have noticed a big difference between fertile and infertile forms. I suspect some of the latter are var. marginale, but this needs confirming.


pf339's picture

Collema spp.

Thanks for helpful information. "Evidence of a pustulate lobe surface.." has made me look through rest of images more carefully and there may be a more convincing possibility. Images are of a different thallus so I shall post the images separately as possibly Collema fuscovirens.
Many thanks