When German smugglers landed in Amsterdam hauling suitcases of contraband destined for their underworld contacts, Dutch customs officials were one step ahead of them. The police busted the traffickers, confiscating their maps and shovels and nearly 1,000 extremely rare cactus plants they had uprooted from the Mexican desert.

The cactus, a plant that Mexicans have long regarded as a useless weed, the dandelion of the desert, has turned into a hot item on the global black market for exotica. Collectors in the United States, Europe and Asia are paying thousands of dollars for a single rare cactus from Mexico, the world's richest cactus breeding ground, in an increasingly sophisticated smuggling network.

Mexico has 850 species of cactuses, many of them extremely valuable. Collectors establish value for the plants based on their size -- tiny cactuses are considered desirable -- rarity and age. Some cactuses are hundreds of years old and no larger than a thumbnail, while others can grow 60 feet high and weigh several tons. It is illegal to take endangered cactus species out of Mexico. But shadowy collectors around the world display Mexican cactuses in private greenhouses and homes, treating them as if they were precious jewels or works of art. Black-market demand has created an underworld trafficking operation that stretches from shovel-wielding poachers who carve the plants from the Mexican desert to the finest European gardens.

"In order to make money on cacti you really have to know the black market," said Jeronimo Reyes Santiago, a biologist and president of the Mexican Cactus Society. "It's like narco-traffickers -- it's one thing to grow the marijuana, but you have to know who is willing to buy it. You have to have the connections. This is really a big problem. And the Europeans are setting the prices."

Victor Lichtinger, Mexico's environment minister, said the country was "trying to get better intelligence on who is buying, creating the black market." He said stripping the desert harms "the traditional richness" of Mexico. "The first thing we need to do is capture these smugglers and put them in jail," he said. "And we need to educate our own people that cactuses have value."

President Vicente Fox met Monday with officials from the World Wildlife Fund who handed him their new report, "Prickly Trade," which concludes that illegal cactus trafficking is devastating the fragile environment of the Chihuahuan Desert, a 250,000-square-mile paradise of biodiversity that spreads from Mexico into Texas, New Mexico and Arizona.

The report said that "commercial exploitation" was leading to a loss of tens of thousands of cactuses from the desert every year. The report estimated that from 1998 to mid-2001, about 100,000 plants, worth about $3 million, were uprooted in Texas or illegally imported from Mexico, destined for American consumers.

The demand for legal cactuses is growing as well. As water becomes increasingly scarce, especially in places like the American Southwest, cactuses are becoming more popular for landscaping and decoration. They are also being used more in herbal remedies and skin lotions, and scientists are now studying them for a variety of medical treatments, from diabetes to schizophrenia.

One species of cactus has even found a niche in the world of computers: The Cereus peruvianus, called the "computer cactus," is being touted on the Internet as helping to absorb static from computer screens, thus reducing eyestrain and headaches.

Many kinds of common cactuses can be sold legally, including the tall saguaros -- the famous three-armed variety seen on Mexican restaurant logos throughout the United States. But Mexico has 270 species that are considered threatened or endangered, and it is illegal to remove them without a permit.

The cactus has long been associated with poverty here, because cactuses tend to grow in the most arid and marginalized regions of the country. Farmers and construction crews have hacked them away by the hundreds of thousands to make way for homes, roads and dams. But as appreciation for the cactus has risen, people are guarding them more. The townspeople in Galeana, in the northern state of Nuevo Leon, not long ago smashed a van carrying Japanese tourists because they were poaching cactuses.

Diana Ponce Nava, a lawyer with the environment ministry's enforcement division, said that two years ago the penalties for illegally exporting rare cactuses were increased to a maximum of nine years in prison. Before that, it was largely a risk-free business, with Europeans even running "cactus trips" to the Mexican desert, where they openly dug up the plants.

"It used to be just people with shovels and suitcases, but the trafficking is getting much more sophisticated," said Ponce, whose agency recently raided the famous Xochimilco flower market just south of Mexico City and a private greenhouse in Monterrey, where they recovered thousands of rare cactuses.

U.S. border agents are finding them, too. In one celebrated cactus bust, U.S. Customs agents, working with U.S. Fish and Wildlife Service investigators, arrested two Americans in 1999 for smuggling 21,000 Mexican ocotillo cactus plants into Texas. Their black-market value was estimated at more than $500,000. Months after the March 2000 bust at the Amsterdam airport, Czech officials confiscated two suitcases containing 72 rare Mexican cactuses, which had been abandoned by smugglers. Before that, a dozen Czechs were nabbed here trying to smuggle $200,000 worth of cactuses dug out of the desert.

Reyes, curator of Mexico's most prized cactus garden, estimated that tens of thousands of cactus plants were smuggled out of Mexico in the 1990s. His giant cactus garden, located at the National Autonomous University of Mexico, includes cactuses that look like huge asparagus spears and others so subtle they are almost impossible to see amid the rocks. His garden is also home to the 72 repatriated cactuses found in the abandoned suitcases in Prague, prized plants worth thousands of dollars.

"I love their capacity to survive," said Reyes, explaining devotees' admiration for cactuses. "Some can live without care for a year or water for a year. They are patient plants. They wait 10 years to sprout a single flower."

Germans and Czechs have repeatedly turned up as illegal collectors and many of the biggest busts of rare cactuses have been at the Frankfurt and Prague airports. Reyes said officials from the Czech Embassy came recently to check on the well-being of the cactuses from the Prague airport bust.

Botanist Martin Smith points out extremely rare specimens at the El Charco del Ingenio garden, home to one of Mexico's largest cactus collections. Cesar Arias, director of the El Charco del Ingenio botanical garden in Guanajuato state, stands among some tall, and very common, cactuses.