This story is published in collaboration with the Guardian as part of its two-year series, This Land Is Your Land, with support from the Society of Environmental Journalists.

When most people drive through the Cactus Forest in Saguaro National Park, their gazes are fixed skyward. Towering saguaros fill the view on either side of the road, rising 40, even 60 feet high, their human-like arms outstretched.

But on a recent December afternoon, Ray O'Neil was focused on the ground. He was looking for holes. As the park's chief ranger, O'Neil is on constant alert for an unusual menace: cactus poachers. Saguaros aren't just beautiful to look at; they also fetch a hefty price, up to $100 a foot, on the black market, where they are enormously popular with landscapers.

As the sideways winter light illuminated the saguaros with a golden effervescence, O'Neil scanned the scene. "People try to steal all kinds of things from the park, even rattlesnakes," said O’Neil, staring out the open window of his SUV. "But cactus has always been the biggest target."

The national park is not alone. Across the Southwest, cacti are being stolen from public lands in increasing numbers. From soaring saguaros to tiny, rare species favored as indoor house plants, the booming global demand for cacti is driving a shadowy, underground trade that's difficult to police. Moreover, experts say, such trends risk destroying sensitive species forever.

In Saguaro National Park, the situation became so grave it prompted a bold solution. In a scheme that made headlines, park workers began inserting microchips the size of pencil tips into cactus trunks, which could be scanned with an electronic reader. While the effort has so far proven effective in thwarting thieves, it has been a rare bright spot in a problem that remains pervasive yet intractable. More than a dozen cactus experts interviewed for this story–government botanists, presidents of regional cactus clubs, and respected Southwest nursery operators—shared tales of crimes that go largely unprosecuted, fueled by unregulated international trade on the Internet.

The Scale of the Problem

In the last decade, cacti have exploded in popularity, becoming a mainstay of hipster decor around the world—from the homes of China's growing middle class and the meticulous cactus gardens in Japan to the fashionable cafes of Europe.

In the United States alone, sales of cacti and succulents surged 64 percent between 2012 and 2017; a market that is now estimated to be worth tens of millions. But rising demand has met a thorny problem: cacti are extremely slow-growing, with some species taking decades to grow from seed to full maturity. Hence, many opt for the shortcut: pulling them right out of the ground.

For land managers and scientists who work with cacti, the problem appears to be on the rise. While the precise scale is difficult to measure, and catching thieves redhanded in remote deserts is nearly impossible, major busts offer clues. In 2014, more than 2,600 stolen cacti were seized at U.S. borders—up from 411 just a year before. But law enforcement officials and field scientists say that data represents only a tiny fraction of cactus actually being stolen.

"When I first started we rarely investigated cactus theft," said one U.S. Fish and Wildlife Service detective, who asked not to be named due to the undercover nature of his work. He has covered the Southwest region for more than a decade and says the problem is increasing. "Now we are prosecuting cases involving thousands of plants at a time. The demand is so high that I fear we can't stop the illegal trade going on."

Luke Hetherington, biological engineer for Saguaro National Park, plants saguaros that were rescued from an old mineshaft that was backfilled. (Photo: Eirini Pajak)

While many plants fall victim to underground cactus cartels, a seemingly more benign form of theft has become part of the problem too. International visitors who come to the Southwest specifically to view rare cactus in the wild sometimes take a souvenir home, and social media is exacerbating the problem.

"We've had Austrian, German, and Italian collectors express strong interest on social media for these plants and they share GPS coordinates," said Wendell "Woody" Minnich, the former president of the Cactus and Succulent Society of America. "Some of these people come to steal, especially when a new species is identified. They hide the plants in their suitcase and take them back to their greenhouse in Europe."

Minnich, 71, has been a cactus grower and nursery operator in New Mexico for 50 years. He said the Internet had significantly accelerated theft of rare, slow-growing cactus species over the last decade. A case in point: Sclerocactus havasupaiensis, which is native to one drainage at the bottom of the Grand Canyon, was being auctioned on eBay in early January by a seller in Ukraine. It was just one of more than 365 internationally protected plant species that are openly traded on Amazon and eBay.

"Do a Google search on Sclerocactus and you can find people in Russia selling them," said Minnich. "I have been on public lands in Arizona, New Mexico, and Colorado where years ago Sclerocactus were everywhere, and recently I found just a bunch of little holes in the ground."

'If You Steal a Cactus, We Will Find You'

Back at Saguaro National Park, the Guardian joined park staff to see the chipping scheme in action. While O'Neil carried a sidearm, park biologist Don Swann packed a yellow chip insertion device resembling a staple gun. With a tiny chip loaded in the barrel, he held the gun flush to a saguaro trunk.

Samuel Arnberger was among the first rangers to insert the RFID chips into the saguaros when the program started. (Photo: Eirini Pajak)

Once inserted, the chip was nearly invisible, leaving only a tiny hole that would eventually scab over. Meanwhile an electric reader, waved over the plant, allowed previous chips to be checked.

Cactus thieves have long targeted the park: One of the most notorious incidents happened in 2007, when a landscaper named Joseph Tillman dug up 17 saguaros with a friend. The pair were apprehended by a ranger while trying to load the stash into a pick-up truck, and Tillman was given eight months in prison, one of the harshest sentences ever for a cactus rustler.

Approximately 700 saguaros have been microchipped since the program began, meaning law enforcement can scan cacti at commercial nurseries in search of missing plants. "We are now able to tie a stolen plant directly back to a hole," O'Neil said.

Since the chips have been installed and the program widely publicized, there have been no known cases of saguaro theft in the park. "It is a very effective deterrent," O'Neil said. "We want people to be aware that if you steal a cactus from us, we will find you."

New Species at Risk

Those who study cactus theft say that changing consumer trends are putting new species at risk. One of the hottest commodities at the moment is Ariocarpus fissuratus, commonly called the living rock cactus. To the untrained observer this little lump of a plant looks completely unremarkable, like a dark green sea sponge. But in the fall, when conditions are right, the cactus is topped with bright pink flowers.

Not-for-profit nurseries across the Southwest often serve as rescue facilities for confiscated wild plants. One of those is the Pima County Native Plant Nursery in Tucson, Arizona. In December last year, the nursery received 200 Ariocarpus fissuratus from a seizure by U.S. Customs and Border Protection. According to Jessie Byrd, the nursery manager, a man was caught with some 2,000 plants, stolen in west Texas, that he was attempting to get across the border into Mexico.

Jessie Byrd, manager for the Pima County Native Plant Nursery in Tucson, holds a Ariocarpus fissuratus, a rare plant that was confiscated from someone crossing the border. (Photo: Eirini Pajak)

Her greenhouse was filled with living rocks being rehabilitated after their stressful journey. "This was stolen because it is coveted by collectors," said Byrd, holding one of the cacti in her hand. The living rock is extremely slow-growing even by cactus standards: the shriveled, black specimen she held was about the size of a tennis ball. She said it was 30 to 40 years old.

In 2015, US officials made another large seizure of Ariocarpus fissuratus and those plants —all 3,500 of them—ended up at a greenhouse in Alpine, Texas, belonging to Sul Ross State University. "You could tell the people who stole the plants were money lovers, not cactus lovers," said Karen Little, Sul Ross' greenhouse manager. "The plants were just yanked out of the ground and stuffed into garbage bags."

Authorities suspect the plants were stolen from nearby public lands, including Big Bend National Park and Big Bend Ranch State Park. "Cactus theft is a huge issue in the Trans Pecos," said Little, referring to the sprawling desert in west Texas where Sul Ross is located. "We have whole genetic lines of cacti that have been wiped out by poachers."

One of the major challenges for conservationists is that the most endangered cacti are the most vulnerable to theft. "The more rare or harder it is to get, the more valuable the cactus is to collectors," said Steven Blackwell, a biologist for the Desert Botanical Garden in Phoenix.

It's a reality Blackwell and his colleagues have experienced with frustrating frequency. In the summer of 2018, while studying endangered acuna cacti at an Air Force training area in southwestern Arizona, he arrived one day to discover his remote research plot had been entirely obliterated. "All the cacti were gone and the ground was full of divots where the plants had been obviously dug up," Blackwell recalled. He never even reported the acuna theft to land managers, because he figured nothing could be done.

Taking the Slow Road

Not everyone has given up hope. Gene Joseph, a longtime Tucson nursery owner, believes the best way to thwart illegal trade is simply doing the slow, steady work of raising new cacti from scratch. Joseph's greenhouse is home to some of the rarest, smallest, and slowest-growing species. "When nurseries are producing rare plants from seed, the pressure to steal from the wild goes down," he explained.

Joseph said it often takes up to two decades for a cactus to reach the commercially viable "specimen" size—he currently sells living rock cactus grown in his nursery for 15 years. That's about as long as it takes to raise a child, so, understandably, he gets attached. "Sometimes it is hard to let go, but I can't keep them forever," he said.

Joseph's facility is comprised of acres of shade houses and greenhouses. With two golden retrievers at his heels, he methodically tends to thousands of plants each day. After his watering rounds are done, he puts on his reading glasses to pinch off tiny seeds from cactus fruit so he can grow more plants, carefully pollinating the flowers by hand.

At the beginning of the new year, the Sul Ross greenhouse manager, Karen Little, was still working on finding permanent places for 1,500 of the 3,500 stolen Ariocarpus fissuratus she inherited in 2015. Due to international trade protections, the endangered cacti cannot be sold and must rather be given away for safekeeping to responsible stewards or other not-for-profit greenhouses. It has been like trying to adopt out a very large litter of stray puppies. Some have gone to trusted collectors, others to nurseries. "It's been my honor to find good homes for them," she says.

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