Observation 65555: Lichen P. Micheli

When: 2011-04-15

Collection location: Davis, California, USA [Click for map]

Who: Byrain

No specimen available

Growing on a wooden fence.


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I was confused…
By: Byrain
2011-04-16 19:25:34 PDT (-0700)

I don’t have any KOH, so I’ll get some.

And this fence is in close proximity to a duck pond, if that could account for the nitrogen.

3% should be okay
By: Jason Hollinger (jason)
2011-04-16 07:39:29 PDT (-0700)

I think the only difference it makes is the speed with which the reaction takes place, not the ultimate outcome. In the present case, parietin reacts instantaneously, so 0 seconds times 3 still equals 0 seconds! :)

Chemical reactions
By: Byrain
2011-04-15 21:35:13 PDT (-0700)

Thanks to your comments in Andrew’s and zaca’s observations, I have an idea about chemical reactions. I only have a 3% solution of KOH on hand, would this be enough to show a reaction? If not, I’ll get some 10% solution within the next few days.

Two species here
By: Jason Hollinger (jason)
2011-04-15 20:26:55 PDT (-0700)

I think the yellow is Candelaria pacifica (or maybe C. concolor, I just know that C. pacifica seems to be more common and would be more likely in California, I think).

The orange should be Xanthoria polycarpa, I think. (Although, Xanthomendoza hasseana is a possibility, I would just have expected to see rhizines in at least a few places if so.)

Incidentally, you can readily confirm the difference in genera because the yellow one should be K- (or K+ slowly pinkish), and the orange K+ immediate, vivid “wine red” (one of the most satisfying chemical reactions you’ll ever see! :)

In any case, both species should be common on exposed fence posts near farm or other source of excess nitrogen (fertilizer or manure).

Created: 2011-04-15 17:47:35 PDT (-0700)
Last modified: 2011-04-16 19:38:19 PDT (-0700)
Viewed: 67 times, last viewed: 2020-05-16 13:46:03 PDT (-0700)
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