A Lafferty Blog
Martian lichen has popped up in a lot of science fiction stories in the '60s. Look at P. K. Dick's "We Can Remember It For Your Wholesale."
Thanks for the tip, Kevin. I've never read "Wholesale," but I've got the 5th SubPress Dick volume on its way to me right now and "Wholesale" is the title story. You've given me a reason to read it sooner rather than later. Martian lichen!