A legendary Ozark chestnut tree, thought extinct, is rediscovered

Steve Bost will show you some Ozark chinquapin trees. “But I’d have to blindfold you before you get in the car,” he jokes.

Deep in the rolling southeast Missouri Ozarks, Bost gets out of his car at the end of a remote dirt road. Somewhere nearby, carefully hidden from the public, is the Ozark chinquapin tree, once a keystone Ozark forest species. Decimated by chestnut blight in the mid-1900s, any viable trees were thought to be long gone—that is, until Bost found a few healthy hangers-on in the 2000s. Now he’s trying to bring the tree back from the edge of blight in a non-traditional way. And he’s succeeding.

Bost wipes his face with spicebush leaves, a natural repellent for a cloud of gnats. A short hike through the woods takes us to a rocky, sunbaked slope ringed by drought-killed trees. On this ridgetop is a test plot that Bost began nine years ago, home to 117 baby and adolescent Ozark chinquapins, some up to 30 feet tall, half the height of a full-grown tree. It’s Bost’s greatest secret and triumph: the genetic future of the Ozark chinquapin.

Not long after taxonomists granted the tree independence from the lookalike Allegheny chinkapin in the 1930s and ‘40s and christened it Castanea ozarkensis, the infamous chestnut blight crossed the Mississippi and the Ozark chinquapin went from being a vital Southern tree to nearly vanishing from cultural memory. The only apparent remnants were Sisyphean stump sprouts, functionally useless shoots that would grow for a few years, become infected with blight, die back to the roots before they could produce nuts, and start over again.

Bost, a 61-year-old Missouri State Parks naturalist, had never even heard of the Ozark chinquapin until about two decades ago. Quickly growing obsessed, he set out on a quest to find surviving chinquapins all around the Ozarks and beyond. Acting on tips, he would sometimes drive to Mississippi and Alabama on time off, hiking around the woods for days looking for one. He says tree field guide authors claimed the tree was gone.

It wasn’t. With the help of other Ozarkers, Bost has located 45 large trees that have resisted chestnut blight, mostly in Missouri and Arkansas. With the support of private and state agencies, he’s leading the effort to bring them back. The Ozark Chinquapin Foundation, which Bost founded, has 15 more test plots in addition to the one we visited—adding about 1,000 test seedlings and saplings to the 45 healthy wild trees. Still, the Ozark chinquapin's continued existence is so fragile that the foundation treats their locations as classified information, protecting the few remaining seed-producing trees from foragers.

“If you start asking people in conservation around here where these trees are, they’ll start getting real quiet,” he says. Until the species’ survival is certain, conservationists won’t tell anyone where they are.

Babying a tree back to life

Bost is going to great pains to keep the Ozark chinquapin line pure. The American chestnut, the chinquapin’s more famous cousin that was also decimated by chestnut blight, is undergoing a genetic concession that Bost refuses to make. In hopes of muscling that tree through to survival, researchers create DNA hybrids that are 15/16 American chestnut and 1/16 blight-resistant Chinese chestnut.

That’s cheating, according to Bost. A tree’s role in an ecosystem is so complex and nuanced, he says, that if you reengineer a species even a little bit, it can have unintended consequences. He prefers the laborious process of collecting pollen from a healthy tree, drying it, jarring it, and driving it 20 hours to another healthy chinquapin to hand-pollinate it.

“The minute you hybridize, you invoke a lot of other influences, and maybe then you don’t have that original species forevermore,” says Meg Lowman, a forest canopy ecologist and director of TREE Foundation who is also a National Geographic grantee.

The hope is to develop a genetic line that can resist the blight enough to once again play a significant role in the Ozark ecosystem. Even with only 45 healthy adult trees, that might be realistic.

“I think they have every chance in the world,” Lowman says. “More threatening situations are when we get down to two Galapagos tortoises or six of a certain species of endangered cat. That’s where people start to have doubts.”

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What’s more, Castanea ozarkensis has managed to cling to more genetic diversity than the devastated Castanea dentata, the American chestnut. A 1999 DNA study in the Journal of the American Society for Horticulture Science suggested that the Ozark chinquapin actually might be the American chestnut’s evolutionary parent.

Still, the order is tall. Off the cuff, leaders at St. Louis’ Missouri Botanical Gardens and Chicago’s Morton Arboretum were unable to name a tree that had been bred back from near-extinction to once again play a vital role in its ecosystem. The Ozark Chinquapin Foundation is in uncharted territory.

A brief history

Among other names, the Ozark chinquapin was known to Cherokee Indians as the bread tree, and they ground the nuts into flour. Settlers in the 1800s used its rot-resistant wood to make fence posts and its bark to produce a purple dye. During Prohibition, moonshiners lit its clear-burning wood to avoid detection from revenuers. Daniel Moerman’s 1998 book Native American Ethnobotany cites the chestnut, part of the same genus, as a treatment for whooping cough.

But the sweet-tasting nut, released from a small golden hedgehog of a burr, was the real prize. A protein jackpot, it attracted more wildlife any other Ozark forage. The Ozark Chinquapin Foundation’s game cameras have captured turkeys, deer, bobcats, coyotes, and hogs foraging for the nuts.

“People would go out and get a whole sack, a half a bushel of them,” says Hearold Adams, 99, of Deer, Arkansas. “That’s how good they were. Then all of a sudden, they were gone. Most people don’t even remember they ever existed.”

In the late 1990s, Adams was the one who first taught Bost about the lost tree. Near Adams’ home is a ridgeline once known as Bear Pen Ridge. Black bears were so attracted to the heavy concentration of ridgetop chinquapins that locals used the area for trapping.

Bost breaks down why his work with the Ozark chinquapin is significant beyond the species. He brings up the ash tree, which is facing near-complete die-off at the hands of the invasive emerald ash borer. "There's almost 100 percent fatality, and they're not waiting for the emerald ash borer to kill them,” he says. “They're just cutting them down. If somebody cut down every single chinquapin to remove hosts for the chestnut blight, we wouldn't be able to do what we're doing today."

Citizen science at work

Saving the chinquapin isn’t all field work. In a Missouri Botanical Garden laboratory in St. Louis, Leslie Bost, Steve’s daughter, embraces citizen science using a technique to test for blight resistance that she learned from researchers at the SUNY College of Environmental Science and Forestry. Traditionally, it takes 10 years to grow a tree, inject it with blight, and monitor it to see if that tree’s genes are resistant.

Now, by injecting a single leaf with cultured blight, she can find out in five days if a tree is fit to survive. In what’s known as a detached leaf assay, she removes a single leaf from a tree, infects it with blight in the lab, and observes the blight’s rate of spread to determine that plant’s resistance level. The more slowly the disease spreads, the stronger the genes.

Since May, the results of 70 leaf assays have come in: some of the Ozark Chinquapin Foundation’s test plot trees are even more genetically resistant than Chinese chestnut, which does not succumb to chestnut blight. The strongest chinquapins will be chosen for propagation. In other words, what has been theory for a decade is now empirical: Bost’s attempts are working.

Back on the test plot, Bost examines the saplings as if they are his children. The details of the Ozark chinquapin are still coming into focus. Its historic range shifts from map to map; dates of its sudden disappearance in the Ozarks vary from account to account. Its unsettled history lends the tree an air of a mystery not yet solved. Bost is still following its echo back through time.

“What we’re seeing is just a skeleton of what was once there,” he says. “It makes you kind of sad. It’s like seeing dinosaur bones. What did we have that we lost?”