Siliceous rock, rock walls and overhangs, preferring coastal regions
Widely distributed across North America and Europe
This species is
to the Truckee Meadows.
White rim is a type of common lichen. Lichens are complex organisms that arise from symbiotic relationships between fungi and a photosynthesizer, like algae. This crustose lichen will strongly adhere to a surface, like rock or bark, and form a crust-like (crustose) layer that is very difficult to separate from the surface without destroying the lichen itself. White Rim generally appears as chalky and looks as though it began smooth, and has since cracked extensively. This lichen is characterized by a whitish gray or pale greenish white upper surface and blueish gray discs. This species may look thick and opaque, tending to grow on exposed siliceous rock, rock walls and overhangs.
A parasitised version of the white rim can appear to be heavily spotted with little black dots. These black spots are where the parasites have compromised the apothecia (fruiting body of the fungi) and altered the color in the process. The healthier the white rim, the more white it will likely be!
The white rim lichen is frequently confused for the whitewash lichen (Phylctis argena), which are also found all over North America, including areas near the Truckee Meadows. Take your camera and compare photos!
Some lichens are believed to contain medicinal qualities -- the Japanese view certain lichens as possible cancer-fighting agents.
Los Angeles Times, Wild About Lichens, May 2021, https://www.latimes.com/archives/la-xpm-2002-jan-14-sci-lichen14-story.html#:~:text=People%20don't%20generally%20eat,they%20are%20difficult%20to%20digest.&text=Lichens%20also%20play%20a%20crucial,increase%20the%20fertility%20of%20soil.
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