Lichens are pioneer plants that grow on rocks, trees, or on the ground where the leaf litter or grass has been disturbed. A symbiotic life form, they consist of an alliance between a fungus body and colonies of one-celled algae. The algae do the photosynthesizing and manufacture food. The fungus provides the structure and decomposes the rock underneath, thus aiding in soil formation.
There are three kinds and each finds its niche in the landscape. 
Crustose lichens attach to rock surfaces. They form crusts in broad round patches. The foliose varieties grow as green leaf-like lobes or plates attached to tree bark or rock. The hanging fruticose lichens are the most advanced types with stalked branches that sometimes resemble weird coral growths.
Lichens are tough and long-lived. They are highly resistant to cold, intense heat and to drought. Their growth is extremely slow. Lichens reproduce by means of spores from the fungi which combine with the algae, or by breaking off and reattaching in new locations.
Small flat rocks and fieldstones in open glades and the exposed surface of boulders, ledges and outcrops on hillsides show off the elaborate artwork of the lichens. The naked shields and rock faces are indescribably crusted, etched and overlayed with detailed figures and designs and interweaved areas of color, wandering watercourse lines, overlapping circles and curiously shaped discs. They are pitted, scarred and covered over with jagged-margined lobes, rosettes and amoeba shapes.
These designs sometimes seem like fanciful maps to unimaginable continents and shorelines, or perhaps aerial photos of cratered deserts on alien and far remote worlds. They remind one of oriental mandalas, abstract paintings, things of the inhuman intuitive imagination of the Earth. This is how it 
might look when the Earth dreams – alternately benign, then nightmarish. And it is depicted here in time’s hard handiwork, in these pictographs of an ultimate and undiscoverable ancient mystery.
We take them for granted and hardly give them a second look ordinarily, but maybe these surfaces, properly viewed, are the very “commonplace book” of reality.
The designs are unaffected and plain, but nevertheless represent a kind of remarkable, even haunting, particularity. What need have we of such baubles and trinkets as the autumn leaves and the spring wildflowers, the clouds and the vast starcapes of night, when even the most modest stones underfoot in this place are so wonderfully decorated by time, wind, water and the long-lived lichens. Nature is whimsical with her immense talent. It’s as if Michaelangelo had painted the sidewalks and doorsteps of the Roman slums rather than the vaulted and incensed ceilings of the Vatican palaces.
These stones are durable artifacts of the Earth and exist almost beyond the treacheries of time. These decorations are worth a long look and a deep contemplation. There is hope and a kind of renewal for us in their fundamental vigor and integrity. Isn’t this the way the world is made, of these randomly spontaneous and subtly beautiful designs and figures and wandering wavering lines? Nature apparently loves this kind of thing. It is her style, her way, her folk art. Never a straight line or a neat square or an even triangle when a curve and then a recurve along another curve, or a wiggle, or a squiggly childish circle, or a branching line, or a meander will do. Never just an easy whitewash when an infinitely-hued palette is available to splash, splatter and fingerpaint with.
It’s the poetry of the real incarnate on stone, in cellular matter. There are unknown and unexplored areas deep within us that resonate to these kindred idiomatic expressions in the landscape around us, these riddles. We are deeply touched by the grace of the commonplace.
