THEY provided the majestic backdrop to countless westerns and were the prickly foe of the Road Runner's adversary, Wile E Coyote.
Now the saguaro cactus has become so popular with thieves in Arizona that the giant plants are to be fitted with electronic security chips.
The sharp needles that form the cacti's natural defences are not enough to ward off enterprising criminals
who dig up prize specimens, selling them for £500 to garden nurseries, landscapers and homeowners who wish to decorate their backyard as desert.
In order to provide a deterrent, as well as means of tracking down the spiky stolen property, the US National Park Service plans to inject tiny microchips into the plants' flesh using a syringe. While the chip does not emit a signal, it will cause an electronic wand to beep if it passes within a foot of the plant.
Officials will then be able to check the saguaros being sold at nurseries or landscape businesses to see if they came from the park.
"Everybody wants a saguaro in their front yard" said Jim McGinnis, who supervises the Arizona Department of Agriculture's office of special investigations.
The saguaro is Arizona's thistle and is unique to the Sonoran Desert, which covers 120,000 square miles of Arizona, California and the northern Mexican states of Baja California and Sonora.
The majestic giants can grow to heights of 50 feet and sprout "arms", but can take 50 years to flower and 70 years before sprouting their first arm. They also weigh several tonnes, which has not deterred thieves.
Last year, 17 saguaros were dug up and stashed for transportation. The culprits were later caught. In other cases, three to five plants have been taken at a time, with the thieves escaping.
Bob Love, chief ranger at southern Arizona's Saguaro National Park, said: "There's probably more of it that occurs than we're aware of."
Plant thieves typically target the young and small specimens in the four- to seven-foot range, which are probably 30 to 50 years old. Plants of that size typically fit in the bed of a pick-up truck; bigger ones require heavy equipment to lift and larger vehicles to haul them.
"Saguaros are the plant that gets the most money," Mr McGinnis said.
The microchip project must first undergo a lengthy environmental compliance study to ensure the chips do not harm the plants themselves or create air quality, soil or endangered species issues.
In the United States, there is a federal precedent for cactus-chipping. The Lake Mead National Recreation Area in Arizona and Nevada began putting microchips in barrel cactuses in 1999 after getting reports of poaching from park visitors.
Desert giants identified with a wave of the wandTHE system of "chipping" the cacti of Arizona is similar to the programmes now in operation to assist in the identification of household pets such as cats and dogs.
Under the planned programme, a microchip would be inserted 2.5cm deep into the plant with a large syringe. The microchips do not emit a signal that would allow them to be tracked if stolen. Instead, each is uniquely encoded, and waving a special wand within about a foot powers the chip to send back its code.
Bob Love, chief ranger at southern Arizona's Saguaro National Park, said it was common to see lorries carrying cacti on roads that intersected the park. "So if we saw something like that, we could momentarily stop them and wave these wands over them," he said.
Officials could also check the saguaros being sold at nurseries or landscape businesses to see if they came from the park, "particularly if we knew that a theft had occurred", Mr Love said. The microchips cost £1 to £2.50 each, while the wands or scanners to read them range from £250 to £1,250. Other costs of the scheme would include the labour required to insert the chips as well as to monitor for cactus thefts.
The officials, insist, however, that while inserting the chips they would also be carrying out crucial research work.
"We would likely gather data, GPS the locations and record heights and widths and measures," Mr Love said.
