BOGOTA — Maybe money does grow on trees. This week, in the Ciudad del Río sector of Medellín, Colombia's second largest city, passersby were surprised to see a tree "flowering" with banknotes. Fastened to the tree's branches (with laundry clips) were real peso bills.

Too good to be true? Some people seemed to think so and chose to just observe. But others took the liberty of "harvesting" the money, helping themselves to a banknote or two. Looking on, according to witnesses, were eight coordinators to keep things from getting too rowdy.

A similar scene unfolded near the Museo de la Tertulia, in Cali. And in Bogota, the capital, a tree in the El Virrey park was adorned with money the previous day, April 2.

The big question, of course, is where the money came from.

Alberto Meneses, an events organizer in Medellín, was one of many caught off guard by the sight in Ciudad del Río. "I asked what was happening and nobody said anything. But people began arriving and taking 20,000 and 50,000-peso bills (worth $7 and $18 respectively), so I decided to grab one," he told the Spanish news agency EFE. "It was exciting to see so much money in one place. Everyone was happy."

The big question, of course, is where the money came from. Who put it there and why? One theory is that it the trees were decorated as part of a sociology study. A bank employee said he saw a cameraman by one of the trees filming people's behavior. Others claim it was a publicity stunt by the online film company Netflix, though in a Twitter post, Netflix Latin America denied any involvement. Still others think it was organized by an artist collective.

Either way, the stunt seemed to produce a fairly universal reaction: pure delight! For a few minutes, anyway, the money trees brightened up Colombia's largest cities with some unusually giddy smiles.