In 1964, athletes taking part in the Tokyo Olympics brought with them seeds from their homelands to be planted as commemorative trees.

More than 50 years later, Japan is now searching for the whereabouts of these arboreal legacies as it prepares to host the Tokyo Olympic and Paralympic Games in two years' time.

Records kept at the National Land Afforestation Promotion Organization show some 270 species from over 40 nations were brought in exchange for Japanese species and that the organization requested the authorities to support the initiative by arranging for swift processing of the seeds at quarantine and customs offices.

No national records on where the trees were planted exist. Many are believed to have died since they were growing in a different climate, although some trees are known to have survived in Tokyo's Yoyogi Park and at a school in Hokkaido.

An official of Yoyogi Park, the site of the former athletes' village where 1,100 trees were planted after the 1964 games, hopes that athletes from countries that donated the seeds will pay a visit.

A school in the Hokkaido town of Engaru has more than 150 trees grown from seeds from Canada and elsewhere, suited to the environment of Japan's northernmost prefecture. Some of the trees now reach about 30 meters in height.

In mid-May, children planted seeds taken from the trees as the town seeks to grow a new generation of commemorative trees in time for the 2020 Tokyo Games.

"We would like to pass down the legacy to the next generation," said Engaru town mayor Shuichi Sasaki.

The town is also seeking to hold exchanges with athletes from countries that brought the seeds in addition to pruning some of the trees and using them for the interior of a museum scheduled for completion in Tokyo in 2019 that introduces the history of the Olympics.

The National Land Afforestation Promotion Organization seeks to leverage the commemorative tree campaign to heighten momentum for the 2020 Tokyo Games but because no centralized records exist on where the trees were planted, it has to resort to checking municipal records and asking locals who might remember.

Yamaguchi Prefecture, which received 1,700 saplings grown from the seeds that it shared among local municipalities, said it has been able to confirm the location of one tree at its agriculture and forestry technology center.

Another tree was found at Kumamoto Prefecture's forestry research facility, but the country of origin remains unknown.

"We only have about two years to go to the 2020 games," said an official from the afforestation promotion organization. "We hope people will trace the whereabouts of the commemorative trees and build momentum for the event."