It's not every day—or even every decade—that a new species of conifer is found in the world's temperate forests. But late last year, researchers announced a new species of hemlock tree from Korea, proving that even our best-studied forests still hold surprises.

The new tree could help save one of its better-known cousins—a North American hemlock species being annihilated by a voracious insect. But the new find is so rare that it’s already being considered for an endangered-species listing itself.

“It’s probably the rarest woody plant in Korea, if not the world,” says Peter Del Tredici, a botanist at Harvard University’s Arnold Arboretum in Boston, who was on the team that discovered the tree.

Hemlocks—no relation to the carrot-family plant that killed