In California's Nevada County, an unusual explorer with an unusual name — Amigo Bob Cantisano — hunts for remnants of the Gold Rush, just not the kind you might expect.

The treasures Cantisano seeks are trees: the fruits and nuts planted at homesteads and stagecoach stops in the late 1800s. Despite decades of neglect, many are still highly productive and could prove valuable at a time when California faces drought and the effects of climate change.

Cantisano and two partners run a nonprofit organization, the Felix Gillet Institute. They find, identify and propagate heirloom fruits and nuts.

At his home outside Nevada City, in the northeastern part of California, Cantisano (the "Amigo" was a high school nickname that stuck) walks around his garden and nursery, pointing to a plant he calls the Kate Wolf lilac. The folk singer/songwriter spent summers nearby at an old mining camp and, decades ago, she told Cantisano the backstory of her song "The Lilac and the Apple."

"Kate wrote the song about walking into an old homestead, with the house no longer there, and finding this apple and lilac growing on a hill," planted by miners and mill workers, he says.

"After she passed away, I started wondering about where that was," he says.

After years of searching, Cantisano acted on a lead, walking for hours in a forest when, bingo: The lilac and the apple were still growing. He took cuttings, and he's been nurturing them in his nursery ever since.

Driving through Gold Rush country, Cantisano points out a 120-year-old pear tree standing tall between a community hall and a gas station.

"It's thrown huge crops every year in the drought. It doesn't get diseases, it doesn't get insects. Nobody prunes it, nobody waters it, nobody fertilizes it, and it is just prolific as heck. I've picked over 500 pounds of pears off of it," he says.

He says these resilient heirloom trees have lessons for today's California growers, where highly tended crops face drought, pests and disease.

"If we can figure out how to take those characteristics and meld them into modern agriculture, we're going to have a more sustainable agriculture," he says.

With a name like Amigo, dreadlocks down to his waist, and a year-round outfit of shorts and tie-dye, Cantisano has had plenty of people write him off over the years.

"I'm a hippie, OK!" he says with a laugh.

He's also an influential founding figure in California's organic agriculture movement. He was practically born into this work, crawling around his grandmother's organic garden before anyone used the term. Living in San Francisco communes as a teenager, Cantisano provided food by gardening. At the first Earth Day in 1970, he heard about pesticide hazards.

"A light bulb went on, as they say," he recalls. Eventually he moved to Nevada County, where he ran an organic garden supply store. That's when he learned about Felix Gillet, the Frenchman who opened a nursery in Nevada City in the late 1800s.

"Gillet had plants from almost 35 countries. He was a plant maniac," says Cantisano. He believes many of the trees still growing in the Sierra originated in Gillet's nursery.

Tom Gradziel, of the Department of Plant Sciences at the University of California, Davis, says a lot of California agriculture was built on the expertise of nurserymen like Gillet.

"Now we can just go to the grocery store, and there are only one or two varieties of any given fruit or nut," he says. "Nurserymen like Gillet would be appalled."

Lack of diversity in varieties isn't only dull for our taste buds, he says — it makes crops vulnerable to being wiped out. "The more diverse material we have in both commercial fields and in the backyard, the more resilience there'll be to better contain disease and pests," he says. While one variety might perish, another might survive.

As a breeder, Gradziel says maintaining diverse varieties is crucial: "The more we find with proven adaptability — and the stuff Bob's finding has proven itself in adaptability — the better."

When Cantisano drives up to a property filled with mature trees, he sees Gillet's living legacy. "This homestead clearly has Gillet vibe all through it," he says. He and homeowner Sidonie Christian, a longtime friend, rake the porcupine-like pods of chestnuts that have fallen to the ground, then peel and toss them in a basket. Of the 100 chestnuts he and his partners have tested, Cantisano says these are the best.

"We believe it's called the Marron de Lyon, which means it's from Lyon, France," Cantisano says. "Judging from the leaf shape, the size of the nut and the structure of the plant, it looks like it's a European chestnut." The University of Pennsylvania is testing this chestnut's DNA to find out for certain.

As they harvest, Christian tells Cantisano about county workers who were doing maintenance nearby and almost ran a beloved apple tree through a chipper.

So, what's the impact of losing a century-old heritage tree?

"If we lose a tree like this chestnut, we lose the genetics of a particularly hearty, productive, high-quality plant. You can't find those everywhere," Cantisano says.

But these trees are important for people and neighborhoods, too, says Christian, as she points around.

"Generations of kids have eaten apples off that tree. Lots of people put chestnuts off this tree into their Thanksgiving stuffing and have done for years," Christian says.

For Cantisano, this work connects human and botanical history. He says he'll often stand in front of an old tree "and just stop and try and feel the vibe of the person who planted it."

He realizes it sounds a little odd, but "I've had trees talk to me, like, 'Thank you. You're taking care of me again. I've been alone,' " not picked for decades.

"There is a spirit in those plants," he says. A spirit he's trying to keep alive.

SeparatorCopyright 2016 NPR. To see more, visit