The white-flowered Bartlett's rātā tree is rarer in the wild than the kākāpō but those trying to save the critically endangered species are positive about its future.
It’s a little-known tree and there is no rhyme or reason to when it flowers. Scientists also have no idea how it pollinates.
But what is known, is that there are only 13 left in the wild, with one flowering at a Lower Hutt Scenic Reserve, much to the amazement of botanists.
A Te Papa botanist says for such a large tree, the unknowns are surprising.
“It's very usual to find plants that are new to science but trees and something as big as this, is actually very unusual,” says Dr Carlos Lehnebach, Te Papa Botany Collection.
It is the first time this particular Bartlett's rātā, at Percy's Scenic Reserve, has flowered and that's significant because it’s from a different gene pool to others that have flowered in this reserve before.
Scientists and ecologists are running tests to find out how this rātā's pollination works.
And they then want to cross-pollinate with the newly-flowering tree.
Scientists hope they'll be able to prevent the tree from becoming extinct but it's also facing other threats similar to the pohutakawa, from possums and myrtle rust.
“The myrtle rust is pretty bad because it will damage the flowers and if you damage the flowers then you won't have fruit and therefore you won't have seeds and if you have a species that doesn't like its own pollen that adds another level of difficulty in the reproduction,” says Dr Lehnebach.