An Australian tree that had its heyday in the last ice age is now teetering on the brink of extinction — but ecologists say it could still have a future in Australian gardens, thanks to a rescue plan reminiscent of the hugely popular Wollemi pine.
Key points:
- There are now just six known Mongarlowe mallees, which are just far enough apart to never naturally reproduce
- The NSW government's 'Saving our Species' team believe they are one of Australia's oldest trees
- NSW environment ecologist John Briggs says the tree, which had its heyday in the last ice age, needs human help to survive
The Mongarlowe mallee was once widespread through southern New South Wales, but it's now so rare there are just six known survivors.
Threatened species officer with the NSW Department of Environment, Genevieve Wright, said the number of the trees — known scientifically as Eucalyptus recurva — is at critically low levels.
And to make matters worse, the six trees are spread over a 30-kilometre range — just far enough apart to never naturally reproduce.
"Because they're so far apart the insects don't go between plants, so there's no pollination occurring. And so yes, they do spend a lot of time on their own," Ms Wright said.
"This species has a sort of a nickname, the 'ice age gum'. So we're thinking that thousands of years ago and the last ice age is when there are a lot more plants around.
"But since the climate has changed over time, the environment for the species is less suitable."
The Mongarlowe mallee is known from only two southern NSW populations – one near Braidwood, and another east of Tarago.
It owes its tenuous survival to the fact that it grows on what farmers might've once called 'rubbish country', shallow rocky soil that sheep and cattle avoid.
So, unlike other species of plants and animals that have been driven to extinction by human disturbance, this eucalypt had begun its slow decline many tens of 1,000s of years ago.
NSW environment ecologist John Briggs said the tree now needs human help to survive.
"I believe it's one of the rare cases of a species headed for natural extinction that we're actually able to see because all known individuals occur in this heathland which is not suitable for grazing," Mr Briggs said.
"So we think in fact there hasn't been any loss following European settlement for this species."
Mr Briggs and the NSW government's 'Saving our Species' team has been working to conserve the mallee for more than two decades and now believe they are one of Australia's oldest trees.
"One plant we feel we can age is at least we think 3,000 years old. So it might live another 3,000 years," Mr Briggs said.
To the uninitiated, it's hard to imagine the 2.5 metre scrubby tree possibly being so ancient.
But as ecologists explain, this mallee species resprouts from an underground 'lignotuber' after fire or die-back, so never reaches towering heights.
One of the trees is so old, its base has spread across 12 metres of ground with multiple trunks.
"I suspect they could well have been isolated [from each other] for thousands of years," Mr Briggs said.
"And if we want to get any new individuals then we have to do something, we have to intervene."
The team from NSW environment has made repeated visits to the trees' secret locations, studying the frequency of flowering.
And last year, after 20 years wait, two trees finally flowered at the same time, allowing officers to cross-pollinate them by hand.
So, for the first time in potentially thousands of years, several of the Mongarlowe mallee trees are now bearing seeds – which have been sent to the Australian National Botanic Gardens in Canberra for cultivation.
If their pioneering project is successful, ecologists want to repopulate the wild to offer surviving plants a chance to naturally multiply.
And there's also likely to be immense interest from Australian gardeners.
"Many people would love to have this plant in the garden being such a rare species," Mr Briggs said.
"It's much rarer than the Wollemi pine, and people flocked to having that growing in their gardens.
"It's such an unusual eucalypt so it would be a tragedy to lose it."
Genevieve Wright agreed, and said it would be a "fantastic garden plant"
"Like the Wollemi pine, Eucalyptus recurva has a beautiful leaf shape to it," she said.
"This is the rarest eucalypt in Australia, we've only got six known plants. I think it would be fantastic in people's gardens."