Discovering Pin Lichens

Emily Stone

Existing right under our noses, but mostly beneath our notice, pin lichens form a black stubble on the exposed wood of bark-less trees. When viewed up close, they reveal a whole new world. Photo by Emily Stone.
Existing right under our noses, but mostly beneath our notice, pin lichens form a black stubble on the exposed wood of bark-less trees. When viewed up close, they reveal a whole new world. Photos by Emily Stone.

I was standing at the information desk, in the foyer of Lakewoods Resort, when the lichenologist returned from the field. Matt Nelsen is a postdoctoral researcher at the Field Museum in Chicago, and he gave a talk on lichen biology during the recent Northwoods Foray of the North American Mycological Association. 

I’d missed his talk due to my coordinator duties, so I eavesdropped eagerly as he chatted with a colleague about a chunk of dead wood he was holding. He’d been out exploring the Rainbow Lake Wilderness Area northwest of Drummond, where in 1990 the U.S. Forest Service had found 190 species of lichens during a survey.

According to Matt, he’d just happened to notice a decorticated snag that looked like it would be prime habitat for pin lichens. He said this with a lopsided smile and self-depreciating chuckle. Yes, scientists are aware that many of the words they use could be replaced with plainer language. Decorticated simply means the bark, rind, or husk has been removed. In the dictionary, “decorticated peanuts” is given as the example. In Matt’s defense, texts on lichens use the word decorticated frequently and, in my opinion, big words can often add poetry, precision, and entertainment value to a sentence. 

Anyway, Matt was right. The decorticated snag was covered in pin lichens. When he held out the specimen of fibrous wood he’d sliced off so that we could get a better look, all I could see was a little black stubble on the surface. 
That was enough to pique my curiosity, though, and I followed Matt downstairs to the voucher room, where scientists worked with microscopes, technical keys, and each other to identify the more than 600 types of fungi collected at the foray. Although lichens are a symbiotic relationship between a fungus and an alga, they are classified by their fungus, and so their study traditionally falls under the jurisdiction of mycologists. 

One of those mycologists had brought with them the most amazing dissecting microscope I’ve ever seen. This type of microscope is meant for viewing objects through relatively low magnification, as opposed to a compound microscope that uses higher power magnification to look at things like bacteria and cells. The paired eyepieces provide for three-dimensional viewing, and lights all around the microscope’s stage illuminate the subject perfectly. 

On the way downstairs, Matt had rattled off a bunch of the pin lichen’s unique characteristics. Some species of pin lichens are used as “old-growth indicators,” because they are picky about their habitat being undisturbed. The thallus, or body of the lichen, is inconspicuously buried in the wood. Each of the pin lichen’s “pins” is a stalked apothecium—a type of reproductive structure. At the tip of each stalk is a capitulum—a round cluster of dark brown spores enclosed in a thin membrane. Unlike many fungi who actively expel their spores, the outer coating of a pin lichen’s capitulum simply dissolves, and the spores might cling to the fur or feathers of passing animals, or be dispersed by wind or rain. Underneath the capitulum is a ring of yellow-green crystals containing vulpinic acid, and whose purpose is unknown. 

After Matt placed the drab chunk of wood on the microscope’s stage, it took me a few minutes to adjust the eyepieces and focus. As a naturalist, most of my training has been in looking at the world from the “thousand foot view,” with the naked eye, or with a hand lens. This was a whole new world. Linear ravines and ridges ran the length of the pale, fibrous substrate. On those ridges grew a savanna-like spread of Dr. Seuss-like, stalked, apothecia “trees.” And decorating the lower canopy of each “tree” was a ring of luminous green crystals. I felt like I’d just discovered a forest with its foliage made of gemstones.

Up and down I focused, immersing myself in this fairyland. My eyes galloped over the ridges, alighted in the canopies, and shimmied up and down the slender-stalked apothecia. How does something as beautiful as this exist in our world with so little notice taken of it? Any lichenologists reading this are probably chuckling at my naivety since they learned about it long ago. A portion of the rest of you probably think I’m crazy, and maybe a few others are grabbing their boots, hand lens, and knife to go investigate the nearest decorticated tree. Looking for lichens in Wisconsin should be pretty easy—there are over 662 species recorded from across the state, and 255 of those are found right here in Bayfield County. 

So, filled with wonder and my new knowledge, I wanted to see if I could discover pin lichens again, this time on my own, in their natural habitat. Remembering Matt’s words, I headed down the street in search of a decorticated tree. At the edge of the forest in the Museum’s natural play area stood an old, bare white pine that I’d never paid much heed. Nosing in, I found them right away. Tiny black pins covered at least three square feet of the snag’s sunny side.  Each new natural neighbor I discover becomes a friend whom I can meet up with during a day in the woods.

“I think there isn’t anything in this world I don’t admire. If there is, I don’t know what it is. I haven’t met it yet. Nor expect to.” – Mary Oliver, Hum.


Special Note: Emily’s book, Natural Connections: Exploring Northwoods Nature through Science and Your Senses is here! Order your copy at Listen to the podcast at!


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