They’re common as grass up here, and far more populous than trees. Lichens are everywhere, although I mostly notice them on rocks. Their ubiquity works against them, I suppose, makes it easy to skim past them with quick categorizing glances: the frilly pale green lichen, that orange one, the fluorescent lime variety. They’re also small and low to the ground—so much so that in some cases they are the ground.

Since it’s hard to march purposefully over rocks, I tend to steer around the places where lichen are most prominent, particularly if I’m going out to catch a horse or trying to get blood circulating after too much sitting. As a result, there are plenty of areas, including spots near the house, where I don’t spent a lot of time. I began aiming for rocky patches a few weeks ago, however, seeking in them refreshment of novelty after months of seeing the same dormant grasses and winter-bound evergreens.

I’ve decided that lichenology is like astronomy. Both are studies of realms from which the observer is distanced by disunity of scale and improbable lifeways. As you might expect from organisms that function as symbiotic partnerships between fungus and algae, the biology gets a bit involved, so I hope you’ll allow me to stick to superficial elements. After all, that’s what lichens do.

When I say lichens are everywhere, I mean everywhere, not just all over the place here where I live, but all over the world. They grow on rocks and trees and walls and dirt, doing so in deserts, on the tundra, on coastal shores, on mountaintops, on waste sites. They can dissolve rocks (albeit slowly), creating soil out of stone. As pioneer species, they’re often the first to brave destruction zones. Of the thousands of known species, about a thousand occur in the Rocky Mountains. Most of these are so small they cannot be identified without a microscope, and are presumably often mistaken for the materials they colonize.

My 1998 Lone Pine field guide, Plants of the Rocky Mountains, forgoes Latinate terms such as “squamulose” or “filamentous” for a more poetic scheme to characterize growth forms: dust, crust, scale, leaf, club, shrub, and hair. Lichens incline us to the poetic, it seems, their oddness urging a symbiotic partnership of the literal and the metaphorical in talking about them. Far more so than with birds or plants, the common names for lichen veer toward whimsy: Sockeye scale, Blistered rocktripe, Freckle pelt, Pink-eyed rockbright, Powdered paw, Peppered vinyl, Brown-eyed sunshine, Weathered ruffle, Ragged snow, Colorado rockfrog, Pincushion orange, Rockworm, Peppered pixie-cup, Sugary beard, Wooly coral.

Pretty sure this one is Pink-eyed rockbright (Rhizoplaca chrysoleuca)

The shape of their parts and their growth habits are foliar, flowing, and fleshy rather than crystalline, chiseled, or mathematically angular. Beyond those generalities, however, characterizing lichen requires uncanny mashups and an utter disregard for scale. I have a hard time coming up with images for them without violating boundaries of theme or intellectual discipline. A lichen that resembles lizard skin is nestled next to a spiral galaxy, while a free-form fleur-de-lis curls, unwilted, next to a sunburst. Like a world map arranged across the bulge of boulder, I can see continents, atolls, mountain ranges, plains, and seas: landscapes within the landscape. I find myself collecting picturesque phrases as I wander: akin to miniature coral, looks like crumpled paper, reminds me of tiny fronds of sea fan. Would I describe that as a fairy cup or an impact crater? This one sandpapery, that one pocked, another freckled, others warty. Revisiting the pages of my field guide, common names that sounded cutesy and fanciful a few weeks ago now seem penetratingly exact.

Whether the fungal/algal relationship is symbiotic or parasitic (most sources lean toward the former but concede to the possibility of the latter), it results in colors that all seem to be borrowed from other classes of life and matter: sage green, rust orange, leather brown, designer taupe, mustard yellow, smoky gray, olive, graphite. The hues aren’t showy, but they are assiduous. As long as lichens are alive, they hold their color—and they live a long time. Some people believe they’re among the oldest organisms on the planet. They’re good at tolerating desiccation and bad at tolerating of air pollution, qualities that invite further reflection on the nature of my home place. In that, at least, there’s nothing unusual about lichens. Whenever I start peering closely at an aspect of the world beyond the doorstep, I soon find myself in over my head.

I’ve now lived here long enough to find little colonies—most likely Colorado rockfrog—starting to grow on flagstones we set in place when we moved here twenty years ago. Something about this warps my brain a little, but after hanging around with lichens for a while, I’m starting to get used to that.