Observation 87042: Caloplaca citrina (Hoffm.) Th. Fr.
When: 2012-01-27
Who: Byrain
No herbarium specimen

Notes: Growing on a stone sidewalk curb. I applied chemicals to q-tips and then wiped the thallus to quickly realize that the rxn color appeared on the q-tips, any suggestions on how get KC/CK rxns with this method? I tried applying K and then C onto the same q-tip before applying it to the thallus, but only got more red and yellow.

Proposed Names

28% (1)
Recognized by sight
84% (1)
Recognized by sight: leprose bright yellow crust on sidewalk
Used references: Wetmore, C.M. 2001. The Caloplaca citrina group in north and central America. The Bryologist, 104(1): 1-11.
Based on chemical features: K+ strong wine-red

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Brilliant technique!
By: Jason Hollinger (jason)
2012-01-27 20:46:50 PST (-0800)

I wonder if it works well with other more subtle reactions like the C+ pink of gyrophoric acid.

In any case, the strong K+r clearly indicates Caloplaca citrina. Turns out there’s a whole group of the blasted things, but C. citrina is by far the most common and widespread. C. chrysodeta is the most frequently confused, according to Wetmore: “C. chrysodeta is strictly on calcareous rocks in shady moist places and has a brownish orange color, frequently with a white cottony medulla.” C. citrina is in exposed locations on any kind of rock and occasionally wood, with a bright yellow color. C. tominii is on soil in deserts. “C. xanthostigmoidea has coarse soredia and granules approacing isidia and occurs on rock, bark, wood, and bryophyes”, mostly in the east, especially New England coast. These are the only species reported for North America so far.

Created: 2012-01-27 19:14:38 PST (-0800)
Last modified: 2012-01-27 20:41:00 PST (-0800)
Viewed: 49 times, last viewed: 2017-06-10 06:28:09 PDT (-0700)
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