This tree before me is not the oldest tree in Wisconsin. Not even close.

It’s a scrubby little birch growing almost horizontally out of the side of a cliff of Cambrian sandstone, its trunk barely larger than the barrel of a baseball bat. This tree is not notable. It’s barely even noticeable.

But this tree, unimpressive as it is, is no younger than 80 years old and might be more like 150. It was sampled by Doug Larson, a Canadian scientist who included it in a study he published in 2000. Larson made it his life’s work to study old trees of a particular sort.

In 1997, Larson came to Wisconsin on a research trip from his home in Ontario to look for old trees and take core samples. On that trip, he took a sample from a red cedar, in a part of Brown County called Greenleaf, that his lab estimated to be 1,290 years old.

That is a notable tree.

I found out about Larson’s work when I thought it might be fun to write a story about Wisconsin’s oldest tree. My plan was to track down this tree, check in on it, bask in the shade of its branches and interview its owner (the tree is on private property) about the honor and awesome responsibility of being a steward to such an organism.

I tried hard, truly I did, but I never did find that tree.

All I found was this puny tree, a lousy 150 years old, and on a March afternoon I stood in snow up to my ankles, staring up at it, wishing it were older. But what I was looking at when I craned my neck at that tree was not just a scrubby, unremarkable, not-that-old tree. It was the site of an ancient forest.

It turns out there are ancient forests all around us.

The Niagara Escarpment is home to some of the world's oldest trees

When Wisconsin’s oldest known tree was a seedling, in the early eighth century, Woodland Indians populated the area. Archaeologists know these early residents from their burial mounds. They lived mostly in the southern part of the state.

Across an ocean, not long after Wisconsin’s oldest tree sprouted, Charlemagne was crowned the first Holy Roman emperor. When the Icelandic explorer Leif Erikson in the year 1000 became the first European to set foot on North America, it was a few hundred years old and still not much more than a twig.

Go back further still. Understanding the secret to this tree's long life requires stepping outside of human history altogether, into the mind-bending attenuations of geological time. Go back to the Silurian period, 443 million years ago, when a vast inland sea encompassed parts of northern Wisconsin, Michigan, New York and southern Ontario.

The sea life died and made a layer of limestone, which hardened into a hard rock called dolomite. The seas receded, and for millions of years erosion reshaped the landscape. But that Silurian dolomite was steadfast, hard to erode. Those deposits, in the shape of the shoreline where that ancient sea used to be, formed a snaking line of cliffs hundreds of miles long.

Those cliffs are the Niagara Escarpment. They’re what make Niagara Falls so high. In Wisconsin, the Niagara Escarpment cuts through Door County and down below Green Bay, through the unincorporated area known as Greenleaf.

The secret strategy that has given the oldest known tree in Wisconsin the ability to live so long is the fact that it, like the scrubby 150-year-old tree I beheld with my own eyes in March, is growing out of the side of the cliff.

A millennium of years, and not a single good one

Doug Larson didn’t always study trees. He started his career at the University of Guelph doing lichen biology — “rock scum,” he called it in our recent phone conversation. He looked at lots and lots of rock scum, became a world authority on the subject. He applied for a grant from the Canadian government and was told: No one cares about rock scum.

He looked around, and looked to the Niagara Escarpment, which cuts through Ontario near Guelph. In the same places where lichens are abundant, he noticed, there are trees. They’re twisted, they’re small, they’re scraggly. But they are trees. Maybe, he thought, we could ask questions about how trees grow on rocks?

Larson would spend the next 30 years of his career meticulously proving the case that cliffs are the site of old-growth forests, and that cliff-dwelling trees are among the world’s oldest organisms.

A tree that grows from a cliff doesn’t get struck by lightning. It doesn’t burn in a forest fire. It isn’t cut down by humans who want to grow crops on the land, or build houses with its lumber — not that it has much lumber to give. These trees don't grow much, they don't look like much. But nobody bothers them. And so they live and live.

The Greenleaf tree, the oldest known tree in Wisconsin, was 9 feet tall and 10 inches in diameter when Larson sampled it. It’s inverted, meaning it’s growing upside-down, reaching out and down from the cliff face. Its boughs aren't outspread. It doesn't even reach for the sun.

The side of a cliff face, Larson explained, is a terrible place to grow. The trees struggle for nutrition. Their root systems can’t spread out and take hold. The water they do get comes from drips, not the great rainwater gulps an oak tree takes from the soil.

These cliff-dwelling trees “never do have a good year,” Larson said. “All the years are equally bad.” To measure their age, he used a ¼-inch drilling device, a biopsy needle for trees, to take a core sample small enough that it wouldn’t hurt the tree. He aimed the drill through plastic straws he took from McDonald’s.

He did all this in full rock-climbing harness, hanging from the side of cliffs of 20 feet or more.

In the lab, Larson and his assistants sanded the samples down using ultra-fine sandpaper and scrutinized them with high-powered microscopes. They counted the rings. Some rings, he said, were literally two cells wide. Some years the trees didn’t produce any rings.

“We spent a fortune on radiocarbon dating,” he said, to confirm findings from their counts. It all showed that the counts were accurate. His research was published in peer-reviewed journals. His book, “Cliff Ecology,” advanced scientific understanding of a type of ecosystem no one had thought to study much before. And the results held up. In Canada, Wisconsin, France, Germany, Australia — on cliffs everywhere he looked, he found ancient trees.

Larson took a sample from a tree in France that had been growing there before the Romans left. The oldest tree he ever measured lived for 1,891 years. That one was dead by the time he found it.

Two decades after its discovery, Wisconsin's oldest known tree is back in hiding

In September, I drove through Greenleaf and along the Niagara Escarpment. I had Larson’s 2000 study, which listed latitude and longitude for the tree, and I had a GPS tracking app installed on my phone. It was overcast and muggy. The mosquitoes were thick, having had a weird late-season resurgence.

The tree wasn’t where the GPS tracker said it would be. I drove up and down the roads that ran parallel to the cliffs. I took pictures. I wrote down house numbers and names on mailboxes so I could try to call homeowners.

At one point I got out of my car to look along the cliff for any signs of a juniperus virginiana, which is this tree's species. When I got back in, there were five mosquitoes in the car.

Larson didn't have the name or address of the landowner. When he retired from the University of Guelph, his lab shut down, too. “No one wanted either the materials or the data,” he said, and they were tossed.

But Greenleaf is a small town. People would remember the attention this old tree got in the 1990s, I figured, and someone would know someone who could help me.

Here’s what I tried:

Calling the Wrightstown Town Hall, where the town clerk said she’d heard of the tree but didn’t know where it was.

Leaving my number with Greenleaf Landscaping and Gardens, plus a handful of other nearby businesses.

Consulting Brown County plat maps to find names of the owners of parcels I’d driven by that looked like they were above or below part of the escarpment, then calling people who owned those properties.

Talking to the Brown County horticultural agent, then the former Brown County horticultural agent.

Contacting Larson plus Jeff Nekola, a former University of Wisconsin-Green Bay professor who had been Larson's research partner on their trip, plus Susan Campbell, an ex-Green Bay Press Gazette reporter who accompanied Larson and Nekola and wrote a front-page feature story about their discovery.

Everybody was friendly to me. Many knew of the tree. Nobody remembered exactly where it was.

“This tree is the perfect Wisconsinite,” said Chris Foran, a Milwaukee Journal Sentinel editor, in one of the many meetings where I steered the conversation to this subject. “It’s stubborn as hell, it won’t move, and it’s not going to do a damn thing to make your job any easier.”

'You can hug a tree'

By the time Wisconsin was settled by Europeans, something like 60% of its land was what we now call old-growth forest, according to John Bates, author of “Our Living Ancestors: The History and Ecology of Old-Growth Forests in Wisconsin (and Where to Find Them).” The rest of the land had been burned or altered by weather, or cut down for Native American agriculture. And of this, the state’s famous pinery was a minor component. Only about 9% of the state was white pine, the great trees stalked by Wisconsin’s lumberjacks. And the great, towering white pines themselves were a few hundred years old — some scientists have speculated that they arose here following a season of fires in the late 1400s.

There are trees that survive in Wisconsin from around that time, Bates said in a September book event in Wausau. In the Cathedral Pines Natural Area there’s a tree that is 376 years old. At Peninsula State Park in Door County there’s one that is 507 years old. In Fish Creek, 616 years old. These trees are majestic, massive. They look like organisms that have been alive for hundreds of years should look, according to us.

When Larson studied lichens, he regularly found organisms that were more than 1,000 years old. But that was just rock scum. A tree is different. A tree is an individual. “You can hug a tree,” Larson said.

“What I remember about the tree is, like you, I was expecting something special,” said Campbell, the Green Bay Press-Gazette reporter who rode along with Larson and Nekola back in 1998, who saw the oldest known tree in Wisconsin herself. “It was really unremarkable. That was the only remarkable thing about it. It was just a scraggly-looking cedar. It’s amazing that they found it.”

In Campbell’s story, she quotes Larson saying something he also said to me about these old trees: “They’re hiding in plain view.” And this: “These are the slowest-growing things that have ever been noted in the scientific literature.”

One of the studies Larson later published, in 2000 in the Journal of Biogeography, includes in one of its tables a tree growing from the side of Ship Rock, a striking sandstone formation that seems to rise of out of nothing in the plains of central Wisconsin.

The tree on Ship Rock is not one of the older samples Larson studied. But Ship Rock is a public place. It’s on Google Maps. That’s where I went in March, where I, too, got to feel underwhelmed at the sight of a boring tree, barely noticeable and impossible to get to. Which is just the way, if it is to survive for a thousand more years, a tree would want it.

There are other oldest trees in Wisconsin

One more thing. The now-1,312-year-old tree on the Niagara Escarpment in Greenleaf? It might not be the oldest tree in Wisconsin.

Larson and Nekola took all the samples they could, but they make no claims — not in their scientific work, not in conversation — to have done anything like a comprehensive survey of the state's cliff-dwelling trees. They showed that cliff faces support old-growth forests, and supported the finding in hundreds of samples. And occasionally, everywhere he looked, Larson found trees that had been there for hundreds of years, even a thousand-plus years.

It made for a fascinating scientific finding and a sturdy career for Larson. But it leaves open the possibility that other, unsampled cliff-dwelling trees in Wisconsin might be even older. They may be out there still.

The oldest tree in Wisconsin is growing, barely. Maybe it's the one in Greenleaf, maybe on the escarpment in Door County, maybe somewhere else. Not far away, humans drive cars and build houses, grow corn, expand the number of lanes on the highway. The oldest tree in Wisconsin grows a ring that is one cell wide, two. Some years it doesn’t grow at all. But it is alive, somewhere no one will notice it, persisting. If no one ever finds it again, it will outlive us all.