Photo of lichen community on Lyons Sandstone, by S.L. White, 1999.

Identifications are best guess. Let me know if you have corrections.

M=Moss, not lichen! (Possibly Grimmia??)

Pt=Psora tuckermannii, a squamulose brown lichen with dark brown apothecia. This species turns bright green when wet.

P?=This appears to be another, more reddish species of Psora growing on top of the main clump. Perhaps Psora nipponica.

Ph=A species of Physcia, a light gray to white foliose lichen on rocks, perhaps P. caesia or P. dubia. Other species of this abundant genus are found on tree bark.

Pha=Most likely a species of Phaeophyscia, a darky, dusky grayish-brown group of foliose lichens.

Dm=Dermatocarpon miniatum. This is an “umbilicate” lichen; each small thallus is attached at a central point.

Xe=A small thallus of Xanthoria elegans, a very common orange lichen on rocks, often found in abundance where nitrogen is high, as on rocks near where birds and small mammals perch.

Cr=Candelariella rosulans, a bright yellow crustose lichen found on rocks. The patch of this color above and to the left may also be this, or a similarly colored foliose species, Candelaria concolor.

?=Several clumps of dark brown lichens, unidentified.

Not bad for an area little more than 4 inches square!

Extra Credit: The Lyons Sandstone is almost white in color at this location.