The 4-year-old tree, grown from seeds that spent nearly a year on the International Space Station, shocked monks at a Buddhist temple in Giju, Japan, by blossoming in early April – what they say is years ahead of schedule. The cherry blossom tree had been predicted to take 10 years to bloom.
Additionally, the tree's flowers have bloomed unexpectedly, with five petals per bud rather than the 30 petals its parent displays.
"We are amazed to see how fast it has grown," chief priest Masahiro Kajita told the AFP.
The tree started life as one of 265 seeds from the temple's famous Chujo-hime-seigan-zakura tree in Giju, purported to be more than 1,000 years old. The seeds were brought aboard the ISS in 2008, and came back to Earth eight months later with Japanese astronaut Koichi Wakata.
Other seeds from the mission have blossomed early, leading to speculation that their time in space changed them.
Still, there are non-extra-terrestrial theories. The space seeds could have cross-pollinated, or the Giju tree – the only seed from the temple's tree to ever flower – could simply be a different breed of cherry blossom tree.
Still, scientists have previously found that trees grow faster when exposed to increased amounts of cosmic radiation.
Kaori Tomita-Yokotani, a researcher at the University of Tsukuba, told the AFP that there was no obvious scientific answer for the mysterious blooming space tree.
"From a scientific point of view, we can only say we don't know why."