Observation 185335: Parmelia saxatilis (L.) Ach.

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Recognized by sight
57% (1)
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Used references: ID provided by Jim Bennett

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Jim explained to me that what I thought was soredia is actually isidia
By: Andrew Khitsun (Andrew)
2016-02-07 23:29:07 CST (-0500)

Under my microscope it looks like soredia, but under compound one Jim says it’s clearly isidia. That explains everything: “simple to furcate” rhizines per Thomson are my “simple to tufted” rhizines. Dah!

It’s best to see examples yourself
By: Jason Hollinger (jason)
2014-11-10 20:31:57 CST (-0500)

Of course. Hard to describe these things. Here’s a diagram… which of course will look nothing at all like the real thing(!)… but illustrates the ideals that I try to look for in the field. This should be visible with a 10x loupe. But there are definitely specimens (like yours apparently) which have no branching at all of any sort. Those we’ll just have to guess at based on type of soredia, etc. – gestalt, basically. And this specimen definitely looks just like P. sulcata should… except for the simple rhizines.

Rhizines of two types:
By: Andrew Khitsun (Andrew)
2014-11-10 18:33:51 CST (-0500)

simple ones on the lobe tips; tufted ones in the middle. I think there is a term for tufted rhizines, but I forgot it. But forked is something else if I understand correctly.

Thanks for looking at those rhizines!
By: Jason Hollinger (jason)
2014-11-10 15:57:37 CST (-0500)

So this is a tricky case. P. sulcata is supposed to have squarrose rhizines, P. barrenoae should have simple rhizines. So the literature says. But I don’t like that characterization. I think the thing to look for is forked rhizines. Simple rhizines are, as far as I’m concerned, inconclusive. But if you can find forked rhizines then you’ve got positive proof that it’s P. barrenoae, not just a form of P. sulcata with very few to no squarrose side-branches.

Does that make sense? Squarrose meaning lots of tiny short side-branches at 90° to the main rhizine; forked meaning rhizines splitting into two more or less equal branches or sometimes splitting dichotomously two or even more times. If you ever see P, saxatilis, that’s a good place to learn that particular branching pattern.

P. sulcata can be simple, but will never fork.

Attributes don’t match.
By: Andrew Khitsun (Andrew)
2014-10-23 22:18:58 CDT (-0400)

Rhizines of P.sulcata are supposed to be squarrose, except on young lobes. This lichen has all simple rhizines, both in the center and outer margins of the thallus. K+yellow changing to red on medula, K+yellowish on thallus, C-.

Created: 2014-10-23 22:10:09 CDT (-0400)
Last modified: 2016-02-07 23:31:35 CST (-0500)
Viewed: 47 times, last viewed: 2016-10-22 12:52:37 CDT (-0400)
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