An inventory of the world’s rarest maple tree offers hope for the endangered species, a conservationist said.

Dan Crowley, tree conservation manager at Westonbirt Arboretum in Tetbury, Gloucestershire, was part of a team of researchers studying the Amami maple on an island in southern Japan.

During their research, only 12 adult Amami maples were found in the wild, but the discovery of three female specimens could help ensure the species’ ability to reproduce in the future.

“While we were pleased that the status of wild species is better than feared, they are still critically endangered,” Crowley said.

The team, which included experts from the University of British Columbia and Osaka University, took part in the first comprehensive study of the world’s rarest maple tree on Amami-Oshihma Island.

They said they were encouraged by the presence of females and seedlings, but added that the species’ population was still “dangerously small.”

“We were concerned that there were no females in the population, but five of the trees were flowering and three of them were female. So it’s not great, but it’s still better than we thought,” Crowley said.

“We’ve also seen a lot of seedlings and a lot of younger trees, so there’s hope that they will become established and the population will grow slightly.”

Worldwide, one in five maple species is at high risk of extinction and requires protection measures.

Ikuyo Saeki of Osaka University said: “We found an unexpectedly large number of regenerating trees. This is definitely an exciting discovery.”

“I hope our team can gain more information about the site’s reproduction, genetic diversity and vegetation and continue to communicate with local people and government organizations for future conservation.”

There are five Amami maples in Westonbirt which were planted several years ago and flower every May.

“There are more Amami maples in gardens in the south of England than in the wild,” said Crowley.

“Collections of endangered and threatened species in botanical gardens such as Westonbirt Arboretum provide a place where plants can be protected.

“To secure their future, we would like to see a genetically diverse collection planted in places like Westonbirt Arboretum and botanical collections around the world.”