As far as the plant scientists at the Missouri Botanical Garden in St. Louis know, the tiny purple-and-white flower that recently grew in their greenhouse has never before been seen, at least by experts like them.

On May 3, Justin Lee, a senior horticulturist at the garden, was checking on a group of Karomia gigas tree saplings in a greenhouse when he spotted the flower. The tree, related to mint and originally from Africa, is one of the world’s most critically endangered tree species.

The one-inch-long flower had a halo of light purple petals that sloped downward while a cluster of four white, pollen-bearing stamens poke out.

“It’s a bit odd for a mint flower. It looks flipped inside out,” says Lee. The mint