In 1991 Rodrigo Bernal, a botanist who specializes in palms, was driving into the Tochecito River Basin, a secluded mountain canyon in central Colombia, when he was seized by a sense of foreboding.

Two palm experts were in the car with Dr. Bernal: his late wife, the botanist Gloria Galeano, who worked alongside him at the National University of Colombia in Bogotá; and Andrew Henderson, visiting from the New York Botanical Garden. They were 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. Until the giant sequoias of California were discovered, wax palms were believed to be the tallest trees on earth. A thick wax coats their trunks, something not seen in other palms, and they live where palms aren’t supposed to: on the chilly slopes of the Andes, at elevations as high as 10,000 feet. This has made them notoriously hard to collect and study. “They were these huge, iconic palms no one knew much about,” Dr. Henderson said recently .

The Quindío wax palm — the species predominant in Colombia — was named the country’s national tree in 1985, but the distinction came with little protection. Dr. Bernal and Dr. Galeano warned, in paper after paper, that wax palms were in danger. Many were marooned in pastures and vegetable fields, remnants of forests past. Wax palms cannot reproduce outside a forest: Their seedlings die in full sun, or are eaten by cows and pigs.