Observation 77641: Collema nigrescens (Huds.) DC.
When: 2011-09-25
Who: zaca
No herbarium specimen

Notes: This was the “icing on the cake”: a fertile Collema growing on the bark of a tree, site where up to now had not seen any. Occasionally, I had found Collema at the base of trees near the ground, but deeply “buried” through the cracks of the bark is the first time.

I think this is Collema nigrescens, which differs from Collema subnigrescens by being isidiate. On the other hand, it doesn’t seems to be Collema furfuraceum, because this has bigger lobes with ridges where isidia accumulate.

The results that follow for the dimensions of spores are are lower than real, since, as the spores are hyaline and of acicular form, with my equipment is very difficult to know where they begin or end:
Me = 41.3 × 3.4 µm ; Qe = 12.4 (N=13).

Sorry for the bad photos, but are what I got.

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Comments

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I think C. furfuraceum is only very rarely fertile
By: Jason Hollinger (jason)
2011-10-01 10:50:51 PDT (-0700)

I concur that this is not C. furfuraceum. C. nigrescens should be found throughout eastern North America, yet I’ve managed never to have seen it.

Created: 2011-09-30 13:54:20 PDT (-0700)
Last modified: 2011-09-30 13:54:22 PDT (-0700)
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