MIAMI -

Colombia is the world's second-largest exporter of flowers. More than two-thirds of all flowers sold in the United States come from Colombia. And Miami ranks first among points of entry for flower imports.

U.S. Customs and Border Protection faces the challenge with agriculture specialists. They examine the cut flowers carefully before releasing them into the U.S. market. Besides narcotics, they are also inspecting the flowers for insects and diseases.

Roses, chrysanthemums and carnations are the most popular. On Friday, a Colombian flower shipment brought more than color to Miami International Airport -- when customs found suspicious cylinders in the boxes.

"Heroin was contained in several cylinders and concealed in a shipment of flowers," U.S. Department of Homeland Security spokeswoman Migdalia Travis said in a news release.

The three pounds of illegal narcotics had an estimated street value of $150,000, Travis said. The arrival is not a surprise to Drug Enforcement Administration agents. They said Colombian heroin controls supply east of Mississippi, and Mexican heroin rules the west.

As the U.S. fought the war against drugs, the Colombia flower industry blossomed. In 1991, Congress passed a law that eliminated tariffs on flowers. In 2012, there was a free trade agreement to help keep the price of flowers low in the U.S. From 1991 to 2013, sales have tripled.

OTHER FOILED ATTEMPTS

January 29, JetBlue flight attendant Carla Alvarado attempted to smuggle heroin from Bogota to Orlando. She was getting paid $10,000, police said. 

June 13, customs found similar cylinders under a car a woman was driving to El Paso, Texas. Customs found heroin with an estimated value of $813,000 in the cylinders.