According to Snu Voogelbreinder's Garden of Eden that species, Parmelia conspersa (possibly along with other unidentified lichens), was considered "potently magical and sacred by the Pima and Papago of southern Arizona and northwestern New Mexico." It "makes young men go crazy" when mixed with tobacco and smoked, and its effect has been compared to cannabis.

http://www.jstor.org/pss/2482390

some interesting info on p. conspersa from 1955! if anyone has an account, to get the full paper...

So House, whats the word on the rest of the experience?

Any after effects?
How long did the stoned feeling last?
Make you sleepy?

This is good stuff, I may have a bunch growing around my area as well but I'll wait till I hear back on the full spectrum of the experience before I go smoking fat bowls of the stuff
Thanks for the bioassay!

Xanthoparmelia conspersa [“Peppered rock shield”; syn. Parmelia conspersa]

USES: Medicine (Africa), Dye (Europe)

Xanthoparmelia conspersa has been used in southeastern and eastern Africa to treat snake bite and venereal disease (Brodo et al. 2001). And Xanthoparmelia conspersa was used in England to dye woolens red-brown (Uphof 1959).
Xanthoparmelia conspersa contains usnic, norstictic, and stictic acid (Brodo et al. 2001). This lichen was also found to have some antibiotic properties (Burkholder et al. 1944). A crude extract of Xanthoparmelia conspersa inhibits Bacillus subtilis.

The chemistry of Xanthoparmelia conspersa is not especially unique. In fact, given the state of Xanthoparmelia taxonomy when these ethobotanical reports were made, the actual species could be any of several: I think all isidiate broad-lobed species were lumped back then. So it could well be X. mexicana, X. amableana, X. plittii, etc. (I see 20 species matching this basic description in the Sonoran Flora.)

All contain usnic acid (a common “sunblock” used by a very broad selection of lichen genera and species) in the cortex. Most contain some stictic acid and related substances and/or salazinic acid – also very common substances in a wide range of lichens – in the medulla. But for the most part, lichenologists only know about substances that show up in TLC, so there could well be additional things.

The report that it grows on both rock and (more rarely) dead wood is very typical of Xanthoparmelia, but I’ve observed that most saxicolous lichens will grow on very weathered old dead wood if given a chance.

I’ve never noticed a strong odor with any desert saxicolous crusts, but then again, I don’t make a habit of grinding up lichens and smoking them! (The only lichens whose odor I’ve noticed are a group of cyanolichens, particularly some Sticta, which smell like fish in excessively damp locations — when decomposing?)

I’m not sure what the description “reddish and white and different colors” might mean. Many lichens will discolor when they die, particularly Parmelia s. str., for example, which will often turn reddish and whitish. I personally suspect the reddish color comes from salazinic acid, which turns very dark red in KOH, so I figure as it breaks down and the salazinic acid is exposed to the environment it might change color if bird droppings or other products of decomposition induce the same color change. Unfortunately, in Arizona (i.e., the desert), Xanthoparmelia just sort of desiccates and turns brown or bleaches out in my experience.

does anyone know the growth range of this lichen?..is it found in the PNW?

"On the sunny side of rocks and rarely on wood, sometimes on tiles; throughout northern US, southward in the mountains (Fink 1935)."

"On rocks and rarely on wood, throughout northern United States, and southward in the mountains."

Just a heads up everyone, usnic acid is known to be toxic to animals, and liver toxicity has been reported in humans following oral use over long time. Usnic acid has been used as a weight-control-medication.

Do we know if Usnic acid is psychoactive or just a toxin?
If it's just in there causing a ruckus maybe it could be removed during the hash making process?