BOGOTA, Colombia -- Authorities suspect a new threat is lurking in the mountains and jungles of Colombia. Not a new rebel cadre, but altered coca plants that are bigger, faster-growing and produce more of the compound that gives cocaine its kick.
U.S. drug agents are trying to confirm the existence of the rumored plant in this Andean nation, the world's prime supplier of cocaine. The U.S. Embassy said it has seen no evidence that it exists.
But a scientist who advises Colombia's narcotics police says he has already spotted it in prime coca-growing regions, with the new plants towering over conventional ones, which typically reach heights of 5 feet. Others say that they also have seen the bigger, more robust plant.
"What we hadn't been able to do is find evidence of the plant, but now we are finding it," said Camilo Uribe, the scientist.
Mr. Uribe said that he found the new plants, rising 7 to 10 feet, in the Sierra Nevada in northern Colombia and in La Macarena, a region of savannah and jungle in central Colombia.
"They were giant bushes, with really big leaves," Mr. Uribe said, adding that the leaves produce higher concentrations of alkaloid, the compound that gives cocaine its high.
Giant coca plants also have been spotted in the state of Putumayo, historically a major coca-growing region in southern Colombia, where locals call the new varieties White Bolivian and Black Bolivian.
In a recent forum in Bogota, Eder Sanchez, a peasant leader from Putumayo, said that the Black Bolivian variety is more resistant to herbicides than Tingo Maria, which for years was a favorite among coca growers.
If an herbicide-resistant plant has appeared, it could weaken a pillar of Washington's multibillion-dollar counternarcotics effort in Colombia -- the massive aerial fumigation of Colombia's coca plantations that aims to keep cocaine off U.S. streets by attacking its source.
"We are currently looking at allegations of leaves that are more resistant to spray," a U.S. Drug Enforcement Administration official said from Washington.
