Observation 209204: Caloplaca impolita Arup (Site ID) (Polycauliona impolita)

Occurs on a sandstone outcrop on a small hilltop with scattered Quercus douglasii, but otherwise in a semi-arid grassland setting.

Thallus light orange, sometimes more orange in center, lobes short elongate, 1-2mm, flat, with yellowish-orange pruina and most have very slightly raised tips (not appressed), although this doesn’t seem to be a good character. Apothecia common, <1mm, concentrated in center of thallus, with thick raised thalline margin concolorous with thallus, pruinose when young, disc same color with slight pruina, isidia and soredia absent, K+R.

Of course, ID is technically based on spore isthmus size and crystals/granules in the medulla, neither of which was examined here. Other options include C. saxicola and C. appressa, but general description and keys suggest C. impolita.

Occurs with Caloplaca ignea, Lecanora muralis, Umbilicaria phaea, and many yet to be named.


C. ignea at right, darker red
Lobe tips showing pruina
Apothecia, largest almost 1mm

Proposed Names

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Used references: Nash Sonoran Flora

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Add Comment
Oh yeah!
By: J-Dar
2015-07-08 23:55:34 CDT (-0400)
Because they’re so beautiful!
By: Jason Hollinger (jason)
2015-07-08 11:23:46 CDT (-0400)

C. trachyphylla has a distinctly roughened texture, unmistakable. At least in the Great Basin. I’ve wondered whether it converges with the coastal species and becomes more smooth near the coast. Wouldn’t that be perverse?

I’ve been looking at these for a while
By: J-Dar
2015-07-08 01:18:46 CDT (-0400)

And finally brought some material home to take a closer look. I think there is also C. trachyphylla in this area. Why do I torture myself with Caloplaca??

Add one more reason for me to come visit!
By: Jason Hollinger (jason)
2015-07-08 00:40:59 CDT (-0400)

This group – C. ignea, C. impolita etc. – really baffles me. Fortunately for me, it becomes very simple across the Sierras!