Observation 87127: Physconia Poelt
When: 2012-01-28
Who: Byrain
No herbarium specimen

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Recognized by sight
56% (1)
Recognized by sight

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Eye3 = Observer’s choice
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Way to go!
By: Jason Hollinger (jason)
2012-01-29 12:51:21 CST (-0600)

I wish I had the patience to photograph the underside of all the foliose lichens I collect! Certainly removes all doubt that this is Physconia. Problem is there are several look-alikes in this group:

P. enteroxantha – medulla and soralia slightly yellowish
P. leucoleiptes – only soralia slightly yellowish
P. isidiigera – nothing slightly yellowish
P. detersa – also nothing yellowish, but restricted to Sierras and east, so we can rule this out

Problem is “slightly yellowish” can be impossible to detect with the naked eye, at least not reliably. Best to do a C or KC test. Both (but especially KC) will react yellow/orange if the pigment (secalonic acid A) is present in any significant concentration.

P. enteroxantha in my experience is most common in shaded locations, but all four can grow anywhere seemingly. P. enteroxantha is also the easiest to verify. If you scratch off the cortex, the medulla is often yellow enough that you don’t need to do the test. If not – for example, if the medulla is really thin or just sort of dirty-looking – then you’ve got to do the tests. And it’s very tricky applying reagents to just the soralia, especially since the soredia are so blasted hydrophobic that they refuse to accept it.

You get the idea!

Created: 2012-01-28 22:59:49 CST (-0600)
Last modified: 2012-01-29 12:40:53 CST (-0600)
Viewed: 38 times, last viewed: 2016-12-06 10:54:41 CST (-0600)
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