Some of the tourists had come before. In a video posted to YouTube four years ago a group walks a desert wash beside a scraggy cliff. They are middle-aged and gray-haired, mostly men, some with bloated bellies and ponytails. One man wears a floppy safari hat and a tan vest with the words “RUSSIA” on the back. In the dry riverbed the tourists’ eyes search the jagged slopes, and like excited children on an Easter egg hunt they motion and point. A low voice from behind the camera speaks. Safronov’s swollen hand reaches for something in the rocks.

At the airport, customs agents pulled aside two of the tourists for a routine interview. How long did they plan to stay in the country? Three weeks, the tourists answered.

What was the purpose of their trip?

They were hobbyists, they said, come to see American cacti.

Safronov, Drab, and the others rented a white Chevrolet Tahoe, then drove west.

***

There are 1,480 living species of cacti, all but one indigenous to the Americas. The journal Nature Plants recently studied the level of danger to almost every species on earth––the largest study of any plant taxon––and the alarming result was 31 percent are threatened, the fifth most of any taxonomic group, just behind amphibians and corals. Loss of habitat to humans and the clumsy plodding of livestock factored highly. No surprise. But what shocked the report’s author was that the largest extinction threat comes from horticulture, specifically the illegal collection and trade of cacti. “We’ve always known there was a black market for these plants,” Bárbara Goettsch, the report’s author, told me in a Skype call from England. “But we thought that was not the case anymore.”

Turns out, it’s still very much the case. Last October, Chinese and German customs agents busted a smuggling ring and seized 1,250 plants, some rare and endangered cacti. As might be expected, there are few scholarly reports investigating the cactus black market. One such report, called “Prickly Trade” (the cactus world is full of egregious puns), estimated that in one three-year period people illegally plucked about 100,000 cacti out of the Texas wild or smuggled them over the Mexican border. That was in 2003. Then Internet commerce arrived. A report from 2012 monitored just 24 online cacti sellers for 1,000 purchases. These were not just any 1,000 cacti. Each was listed as an “Appendix I” specie by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which are plants threatened with extinction. To trade any of these, a seller needs a permit. Of the 1,000 cacti researchers monitored, the report found at least 90 percent had traded hands illegally.

There are plenty of laws that protect cacti, but not much enforcement. There are three degrees of internationally recognized CITES listings that restrict trade. In America, it’s illegal to take plants from most federal land. State laws vary––Arizona’s, which requires a person to notify the government before moving most cacti, is one of the more stringent. Although, as with any black market, legal peril only increase an item’s value. Some cacti thieves will pull a plant from the wild because, like with tiger bones or rhino horns, someone will pay a lot of money for it. But cacti are also besieged by those who profess to love the spiny plants—the private hobbyists and horticulturalists who collect and show cacti like paintings or purebred dogs. These people are sometimes disparagingly called cactophiles, which one online commenter wrote, calls to mind “dirty old men in potting sheds.”