“What’s that?” yelled my seven-year-old daughter, Lark. She, Balen, my eleven-year-old son, and I were smooshed together, vying to see the pale insect scuttling under the magnifying glass. It was one of many treasures brought home in a bucket from a hike along a wooded Sierra Nevada trail.

“What about this beautiful turquoise wood?” I asked, grabbing the next treasure from the bucket. “Maybe this is a fungus?” 

“What’s a fungus?” Lark asked.

“You’re a fungus,” Balen said. I should have seen that coming.

“Stop,” I said. “A fungus is like a plant, but it’s not a plant.” 

“An animal?” Lark asked.

“No, not an animal either. It’s a whole other type of life . . .” 

“This is spray paint,” Balen said.

“No . . .” 

But he was right. We flicked off a few paint chips. 

“OK, how about this orange thing?” I hovered over a blob attached to the wood. “Maybe this is a . . . lichen?”

“What’s a lichen?” Lark asked. I immediately regretted saying it, because I didn’t actually know what a lichen was.

“I think it is two things living together. One is a fungus.” 

“It looks like a butt,” Balen said. 

“That’s not helpful, buddy.”

“It does!” Lark yelled. “Look, there is a line right there down the middle!”

“Butt fungus! Butt fungus!” Balen chanted. Lark joined in.

“OK, we’re done.”

Despite my failed foray into home science, I couldn’t stop thinking about lichen. An internet search presented the information I recalled vaguely from high school: a lichen is a combination of two species living together in a mutually beneficial relationship. One partner is a fungus, one of the six kingdoms of life on Earth and the one that includes mushrooms. The other partner is a species of algae or cyanobacteria, both of which are photosynthesizing, primitive, plantlike beings.

Often the first living organisms to colonize a barren area, lichens live in nearly every habitat on Earth, including the hottest deserts, the coldest valleys of Antarctica, submerged in lakes, at the ocean’s edge, and even blowing untethered in the wind. Seemingly lifeless lichens can be resurrected after being placed in an archive box without light or water for more than a decade. They can survive a deep freeze in liquid nitrogen and gamma irradiation at tens of thousands of times the lethal dose for humans. They can survive five hundred times the pressure of the deepest ocean trench—pressure that would pulverize us. Lichens are the only life-form to have survived eighteen months in space, attached to the outside of the International Space Station. 

Still scrolling, I found the world of lichenology (yes, that’s a thing) to be in a state of discovery and confusion. In 2016, Dr. Toby Spribille of the University of Alberta made global headlines when he proved that there was a third partner in the lichen relationship—a type of yeast. Because this news overturned 150 years of science, major news outlets like the New York Times and The Atlantic covered the story. Lichen’s media heyday ended quickly, but strangely, many outlets, including the New York Times just a few years later, went back to promoting the previous model of only two organisms—a fungus and an alga—living together. Were we just not ready for the groundbreaking discovery? It would not be the first time lichen had presented a truth that human culture was not quite ready to grasp. 

Lichens were often used by early human cultures in dyes, spices, perfumes, teas, brandies, and medicine—they produce thousands of chemicals not found elsewhere in nature. However, it wasn’t until the mid-eighteenth century that Western science first acknowledged lichen, when the Swedish botanist Carl Linnaeus identified and named them, simultaneously insulting them as “the poor little peasants of nature.” 

Linnaeus invented the classification system of binomial nomenclature, still used today to name all life-forms by genus and species, the latter defined as a grouping of life-forms able to reproduce and create fertile offspring. Many of us are familiar with our own classification as Homo sapiens. Linnaeus classified lichens as algae. Over the next hundred years, lichenologists fought over their classification: briefly, lichens were mosses; then they were fungi. But lichens continued breaking the classification rules, resisting labels, and thwarting those who wanted to contain them neatly in one box. 

In 1869, the Swiss botanist Simon Schwendener proposed that a lichen was actually two organisms—a dominant fungus keeping an alga prisoner in order to photosynthesize and make its food. Other scientists, unprepared for this truth, dismissed Schwendener’s theory of two species living together as ridiculous and unnatural. Almost a decade later, two German botanists coined the word symbiosis, and ever since, we have “known” that lichen emerge from the mutually beneficial relationship between one alga and one fungus. But, like many things we have “known,” we were wrong. Again.

Since 2016, when the traditional lichen duo became a trio with yeast, Toby Spribille and his lichenologist colleagues have discovered that lichens also can have a bacterial partner that may play an integral role in lichen reproduction and in the original lichenization process (when independently living beings come together to form a symbiosis). Scientists have already identified more than eight hundred species of bacteria involved in these intricate lichen relationships around the globe. 

The party doesn’t stop there. Sometimes there are two species of fungi. Sometimes there are three. Sometimes there are two algae. Sometimes there are algae and cyanobacteria. In fact, using modern metagenomic technologies, Spribille has yet to uncover a lichen that only has one fungus and one alga. Protists and viruses whose exact roles are a mystery can also join in, and they seem to play a critical part in the lichen as a kind of supraorganism. And these supraorganisms are not static: individuals can come and go in lichen relationships in what Spribille recently described as a “lichen marketplace.” 

All this might feel like the final nail in the coffin of the domineering, binary relationship model, but our tendency to dismiss, even villainize, what we don’t understand has remained a powerful driver throughout our species’ brief stint on this planet.

The colorful structure we see when looking at lichen is called a thallus, created by the unique combination of partners. Thalli are unique to the trio, quartet, or symphony of organisms who come together. Simply changing one partner—even the bacteria—can change the appearance of a thallus. And the lichenization process is still a mystery to scientists, as no one has yet been able to grow a fully natural lichen thallus in a laboratory setting. 

Thalli can be crust-thin, distinguishable from the rock or bark they reside on only by color—pale like the color of fog or brilliant like a field of marigolds. Some thalli are foliose, rising in sage-green leaflets, cups, or rosettes. Some thalli are fruticose, like tubes of red lipstick or swinging tufts of green hair. Thalli provide protection, especially from desiccation, allowing the lichen “team” to live together in extreme environments where they could not live alone. 

Scientists have named more than nineteen thousand different lichen species, but there’s a conundrum with such labeling. What do we mean by species when a lichen is a collection of many species that can be traded and exchanged? In both plural and singular, noun and verb, lichen(s) challenge(s) our language and our understanding of an individual being. 

Honestly, I can’t blame Linneaus or others for misidentifying or misclassifying lichens. During my first weeks looking for lichen behind my house in the Sierra Nevada mountains, I misidentified fungus, moss, gum, sap, and rocks. And we can’t forget about the spray paint.

Lark became adept at identification, classifying lichens under her own nomenclature, with names like “ice booger,” “cracky cracker,” and “orange candy teeth.” Although initially offended at her dismissal of our lichen guidebook, I discovered I was the one being narrow-minded. Lichen names are wild. Some California species with names like warty camouflage, wooly foam, and rock licorice barely stand out as eccentric in Lichen Land. 

Over the course of several months, I went from barely knowing lichen existed to seeing them everywhere. Trees. Rocks. The sidewalk. Fences. Abandoned cars. It’s interesting how the unnoticeable become noticeable once we learn more about them. But the learning process wasn’t without difficulty. More than once, I came up from kneeling on the ground, having had my eye inches from the sidewalk, to see people staring skeptically. Telling them, “I was just looking at a lichen!” didn’t help either. 

As I improved in identifying this miniature world, this scape of crusting colors and small tufty towers rising from the bark of ponderosa pine, I lost track of my own world. Scanning branches overhead, I tripped over roots. Perched on coastal boulders with a magnifying glass, I didn’t notice the incoming tide until it salted my ankles. It was as if my brain could operate on only one scale of awareness, one scale of living. In being like a lichen, I couldn’t function as a human. 

Lichens choose to be lichens. They can lichenize and de-lichenize. The individual parts of the lichen can reproduce sexually with members of their own kingdoms, or the whole lichen can reproduce asexually, releasing little lichen “packets” on the wind to settle elsewhere. The oldest lichen fossils date back three hundred million to four hundred million years, meaning they survived or reevolved after several of Earth’s mass global extinctions. 

The oldest living lichen, and one of the oldest living things on Earth, is a species in the Rhizocarpon genus, its pale, yellow crust dotting the Brooks Range in Arctic Alaska for the past ten thousand years. The other record holders also push tens of thousands of years and include colonial species of plants like a two-hundred-thousand-year-old seagrass meadow in the Mediterranean, an eighty-thousand-year-old grove of all-male aspen trees in Utah, or a thirteen-thousand-year-old Jurupa oak grove in California. Clearly, there is something to this strategy of coexistence and cooperation that works.

Living in our fast-paced, disposable, single-use society, where life expectancy continues to drop in many countries, including the United States, I’m humbled by the lichen. While lichens live for thousands of years, in all extremes on Earth, succeeding at interspecies and even interkingdom cooperation, humans still struggle to coexist with all other life on this planet—we even struggle at peace within our own species. Ten thousand years ago, when that pale yellow lichen began growing in Alaska, we were well on our way into propelling what many scientists now call Earth’s sixth great extinction event.

While lichens are nurturing their partnerships, allowing them to elude death and travel in space, we are still shooting at everything that moves, including other humans. But sometimes, I hope we are evolving too. I hope we are evolving to see the disadvantages of “eradicating any creature that may annoy or inconvenience us,” as Rachel Carson said in her landmark book Silent Spring. Instead of focusing on competition, extraction, and exploitation, perhaps we can consider that some of the greatest advances of life on this planet have occurred when two molecules—two beings, many beings, different cultures—were willing to cooperate and be greater than the sum of their parts. 

But if we can’t stop taking land from each other, opening fire on each other, or treating some lives like they don’t matter, and if we can’t stop placing ourselves above all other living things, and if we can’t find our humble place within the greater whole, among the many entities that have been here for millennia before us, then perhaps we deserve to be outsmarted, outlived, and outevolved by a lichenized “butt fungus.”

Notes
Image Credits: All images by author, Charlotte Stevenson.

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