Observation 130501: Xanthoparmelia (Vain.) Hale
When: 2013-03-20
Collection location: Braga, Portugal [Click for map]
No herbarium specimen

Notes: On a granite wall.

Proposed Names

-12% (2)
Recognized by sight
56% (1)
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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It looks …
By: zaca
2013-03-21 07:52:17 EDT (-0400)

very much like X. conspersa that is quite common among us (see, e.g. observation 121390 and observation 121315 for some examples).
This should be K- on thallus and C-, K+ yellow-orange, KC+ orange-red on medulla. Another close species is X. tinctina, which has more globose isidia raher than cylindrical and reacts K+ red on medulla.

TY Jason ;)
By: Elsa (pinknailsgirl)
2013-03-20 20:32:46 EDT (-0400)
For Xanthoparmelia you really only need “K” (KOH or NaOH)
By: Jason Hollinger (jason)
2013-03-20 20:14:08 EDT (-0400)

This is just common household lye. Make up as strong a solution as possible… in my opinion. Others recommend 10% solution. Just affects how long they take and how strong the desired reactions are.

The other common reagent is “C”, or common household bleach. I use it straight out of the bottle, not diluted at all.

In any case, you are interested in determining which lichen acids (if any) are present in the white medulla within the thallus. So scratch off the gray cortex to expose the medulla, then apply first K then C with a toothpick or needle or capillary tube or (last resort) eye-dropper. (The finer the applicator the more control you have and the easier it is to read the results, in my opinion.) It is best to do this under a dissecting microscope, at 30x or 40x magnification. But you’ll be able to see it with just a hand lens, easily enough, too.

Many Xanthoparmelia have salazinic acid (K+ yellow turning dark blood red almost immediately). Others have norstictic (K+ yellow turning bright orange or red), stictic (K+ yellow maybe turning a bit orangish in time), fumarprotocetraric (K- or K+ slowly dingy yellowish-reddish-brown)… and others. But salazinic and stictic are very common and useful to check for.

Another note, by the way: KC test is applying K first, then after a few seconds, applying C to the same spot. CK is the opposite order, C first then K. (CK+ orange indicates diffractaic acid, for example, a unique chemical signature which can be very helpful for Usnea and one or two other groups.)

The color I can see
By: Elsa (pinknailsgirl)
2013-03-20 19:52:37 EDT (-0400)

tomorrow, the rest no. What chemicals would be needed?

Need chemistry to determine species
By: Jason Hollinger (jason)
2013-03-20 19:40:43 EDT (-0400)

At least in most places. There are a bewildering number of species. Yours is one of the isidiate ones. The other character that is usually required is whether it is black or pale brownish underneath.

Created: 2013-03-20 14:09:31 EDT (-0400)
Last modified: 2013-03-20 19:40:59 EDT (-0400)
Viewed: 34 times, last viewed: 2016-10-22 08:34:54 EDT (-0400)
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