Observation 161310: Physcia (Schreb.) Michaux
When: 2014-03-03
Who: zaca
No herbarium specimen

Notes: The infertile thallus is very much that of a Physcia, namely P. aipolia, due to the conspicuous white flecks (macules). However both this species and the similar P. stellaris are unusual in rock (the observation refers to a fence) and both are usually fertile.
Another point of doubt concerns the rhizines (which are black as can be seen in the photo, mainly in the upper-right lobes protunding beyond the margins, whereas usually are not so dark).

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Yeh,
By: zaca
2014-04-06 12:28:31 CDT (-0500)

Sometimes is frustrating, but we like it and always try to “make a room” for wierd specimens.

Just when you think you know a species…
By: Jason Hollinger (jason)
2014-04-06 10:11:40 CDT (-0500)

Along comes something weird like this! I just spent a few hours last night studying a specimen which apparently is “just” Bacidia schweinitzii, something I’ve seen a hundred times, just never quite like this. Frustrating!

It is always very difficult to …
By: zaca
2014-04-05 15:20:08 CDT (-0500)

know the “boundaries” of some species. I bilieve this is P. aipolia, though it grows on rock. Thanks, Jason, for your comment.

I have seen Physcia aipolia with black, even squarrose, rhizines
By: Jason Hollinger (jason)
2014-04-05 13:25:22 CDT (-0500)

I believe Andrew has an observation showing this state from the Great Lakes region of North America (I’m too short on time to search for it now!) I know I had Ernie Brodo look at one such specimen (I, too, refused to believe such a state was admissable :), and he confirmed that he has seen P. aipolia do this, too. It was the most common state, in fact, in the specimens we collected last summer in eastern Washington.

I don’t know if P. stellaris can also do this.

As for growing on rock, I doubt this is out of the question. Look at the (somewhat) similar P. adscendens, which regularly grows on both substrates, for example. I just checked my notes, though, and I have only ever seen it on bark.

Created: 2014-03-13 18:28:13 CDT (-0500)
Last modified: 2014-03-13 18:28:18 CDT (-0500)
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