In 1991 Rodrigo Bernal, a botanist who specializes in palms, was driving into the Tochecito River Basin, a secluded mountain canyon in central Colombia, chasing the Quindío wax palm, the tallest of the world’s palms. Wax palms have long intrigued explorers and botanists for their remarkable height, with some reaching 200 feet. They live where palms aren’t supposed to: on the chilly slopes of the Andes, at elevations as high as 10,000 feet.