Observation 90633: Chrysothrix candelaris (L.) J.R. Laundon
When: 2012-03-10
Who: zaca
No herbarium specimen

Proposed Names

28% (1)
Recognized by sight: thallus entirely powdery leprose, bright yellow, on bark
Used references: British Flora (2009)
Based on chemical features: K-

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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Thanks, Jason.
By: zaca
2012-03-22 18:23:44 EDT (-0400)
It might not be so simple
By: Jason Hollinger (jason)
2012-03-22 18:17:27 EDT (-0400)

The K+ reddish reaction is calycin. True, some Chrysothrix have this substance, but so do many (most?) Candelariella. Also, there are multiple species of both to consider.

Candelariella xanthostigma has rather coarse soredia or isidioid corticate granules (50-100µm in diameter, easily visible to the naked eye); C. efflorescens may be a better match for your observation, since it has fine powdery soredia (20-40µm diameter, appearing as powder to the naked eye). Note that both of these species contain calycin. Also note that both species start out areolate, and break down into soredia in age, so some intact thallus should still be present in all but the very oldest specimens. (The British Flora doesn’t include C. efflorescens, though, so it may not occur in your area.)

According to the British Flora, you have three options in Chrysothrix:

C. flavovirens – greenish, mostly on bark, rhizocarpic acid, K- UV+o
C. chlorina – bright yellow, mostly on siliceous rock, calycin and vulpinic acid, K+r UV+o
C. candelaris – bright yellow, mostly on bark, calycin OR pinastric acid, K+/-r UV-

I eliminate Chrysothrix on the basis …
By: zaca
2012-03-22 17:57:29 EDT (-0400)

of the K reaction, but maybe I shouldn’t.

Could this be Chrysothrix, too?
By: Jason Hollinger (jason)
2012-03-22 01:20:48 EDT (-0400)

I can’t find any parts of the thallus still intact, so maybe it is truly leprose.

Created: 2012-03-21 20:56:28 EDT (-0400)
Last modified: 2012-03-22 18:19:56 EDT (-0400)
Viewed: 234 times, last viewed: 2017-06-10 13:37:00 EDT (-0400)
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