A walk prompts liking to lichen

Before last month, I had never given much thought to lichen. Now I see it everywhere.

“Lichen will be found on almost anything — even plastic,” said Ryan Towe, an AmeriCorps program specialist at Lone Pine State Park. However, one area where you’ll never see lichen, he said, is along busy roads because it’s pollution-averse.

Towe, who calls himself “pretty much self-taught” in the world of lichen, led this late June stroll through the forest, stopping often to point out splotches on rocks, colorful dustings on trees and crust on branches.

One of the first things we learned: Lichen is not a plant.

“Lichen is a symbiotic relationship between a fungus and algae,” Towe said. He paused at a trailside boulder wrapped in mottled earth tones; without close inspection, it would be hard to identify the natural color of the rock. This kind of lichen (crustose) is completely formed to the substrate. “It’s, like, glued on there,” Towe said as he rubbed it with his finger.

Towe said lichen generally grows at a rate of 1 millimeter per year, so this boulder took decades if not more than a century to become so naturally painted. Rust-gold to chartreuse green, lichens will brighten up further with more moisture in the fall. He said the oldest organism on Earth is lichen in the Arctic; carbon dating put it at 8,600 years old.

We walked on, and Towe identified powder-headed tube, sunburst, dog pelt, powderhorn, goldspeck, hammered shield and tile lichen. Most lichen are edible and have long been used in teas and for medicinal purposes.


“Lichen gives the forest an extra layer, a whole new ecosystem,” said Towe, noting that of the estimated 20,000 species of lichen worldwide, about 4,000 turn up in North America.

We learned to divide the types we saw into the three categories that Towe specified for us on our handout: fruticose, crustose or foliose. In laymen’s terms these can be classified structurally as shrubby, crusty or leafy, respectively.

Our group was as varied as what we studied, including a couple of retirees from New Hampshire who live untethered to a home and instead have been RVing around the country for four years; a couple visiting their daughter from out of state; and a 4-year-old traipsing along with her adult, who mostly spoke Spanish together.

At one point everyone stopped to marvel at a few fresh blooms of the Montana state flower, the bitterroot. Poking up out of dry dirt, they added pops of pink to the landscape. Their delicate-looking petals and rarer presence provided the counterpoint to lichen.

It was after Towe enthused about lichens’ ability to weather just about every stress and environment, implying it will be the last thing standing, er, creeping on Earth, that we made our last lichen stop: at a natural mosaic decorating a vertical rock face. We felt the various textures, noticed the interplay between species, and absorbed the strength and diversity of the low-lying wonder.

“I have a question,” the 4-year-old said. “Can you put it on toast?”

Audience development director Margaret E. Davis can be reached at 406-758-4436 or mdavis@dailyinterlake.com