A graceful birch native to Japan is one of the rarest trees in the world. Two decades ago, botanists counted just 21 remaining in the wild, all confined to a single stand in the remote, rugged forest of the Chichibu Mountains — likely far too few for the species, Betula chichibuensis, to sustain itself.

Arboretums scrambled to cultivate the tree, with some success. But now the species may have gained a second chance at survival: Botanists in Britain have collected and germinated seeds from these wild birches for the first time in nearly 30 years.

The new seedlings may help restore genetic diversity to the small population of cultivated trees and fuel efforts to reintroduce them in the wild. “Definitely, it’s a great coup for a very rare species,” said Michael Dosmann, a curator at the Arnold Arboretum of Harvard University, who was not involved in the project.

The mission to save B. chichibuensis is part of a broader undertaking by British and Japanese scientists to survey and collect seeds from all of Japan’s native plants, many of which are found nowhere else in the world.