When: 2008-12-05

Collection location: Sewanee, Franklin Co., Tennessee, USA [Click for map]

Who: Chris Parrish (kitparrish)

No specimen available

Location: 35°13’2.20"N 85°55’18.04"W, el. 544 m. Running Knob Hollow.

These white patches 15-20 cm across are quite common on the sides of sandstone boulders and rock faces along the western rim of the Cumberland Plateau in this area. Their sharp borders suggest an aggressive patch of whitewash dissolving its way through the neighbors.

This image was transferred from its previous home in Observation 15455 because Gary Perlmutter pointed out that the two photos there represented two different species. Thank you, Gary!

CNALH interactive locality map.

Common name: whitewash lichen

Species Lists


Proposed Names

16% (2)
Used references: Identification suggested by Gary Perlmutter. See comment on Observation 15455.
70% (1)
Recognized by sight: White sterile thallus on rock faces, with occasional red spots (you can see this in the lower right)
Used references: Lendemer, J. C. & J. A. Macklin. 2006. Contributions to the lichen flora of Pennsylvania: a preliminary checklist of the lichens of Nescopeck State Park. Opuscula Philolichenum 3:41-48.
Hodkinson, B. P., R. C. Harris, and M. A. Case. 2009. A Checklist of Virginia Lichens. Evansia 26(2): 64-88.
Hodkinson, B. P., R. C. Harris, and M. A. Case. 2010. A Checklist of Virginia Lichens. http://www.duke.edu/~bph8/VirginiaLichens/checklist.html [updated: 14 July, 2010].
Reported in various sources from GA, NC, NY (as ‘Phlyctis sp. – saxicolous’), PA, and VA. A type has recently been designated, but a formal description is pending. Both the morphology and preliminary molecular data apparently support its placement in Phlyctis.
Based on chemical features: The red spots apparently represent extremely abundant norstictic acid (this is one of the very few species for which you can sometimes ‘see’ the secondary compounds).

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= Observer’s choice
= Current consensus


Add Comment
Keys to Sterile Crustose Lichens
By: Brendan Hodkinson (brendanhod)
2010-07-24 15:25:29 CDT (-0500)

We finally have a scientific resource that gives some information on this species (key + photos)! Now people can start identifying it, even though it has still not been formally described. See Lendemer’s recently released ‘Preliminary Keys to the Typically Sterile Crustose Lichens in North America,’ available here:

How can you tell?
By: Jason Hollinger (jason)
2009-03-09 18:42:09 CDT (-0500)

Or how can Gary Perlmutter? :) However you/he did it, I’m ecstatic to finally put a name to this obscure crust you see all over the place in the Smokies!

Be careful, incidentally, of one that looks a lot like this but on closer inspection has radially-fibrous prothallus around the border. According to Brodo this one is Lecanora thysanophora (hope I spelled that right) — also somewhat common in the area.