BOTANISTS have shed light on the remarkable comeback of two rare plant species native to the Tweed, which had been on the brink of extinction.
Small populations of the lamington eyebright and green waxberry were documented on cliffs in the Limpinwood Nature Reserve several decades ago.
But the vulnerable species' populations appear to have miraculously soared, according to a survey conducted by botanists who abseiled into their habitat late last year.
Saving Our Species project officer Justin Mallee said the recently-released findings from the survey were astounding.
"With the lamington eyebright and green waxberry, finding more of those species is highly significant,” Mr Mallee said.
"Finding more of those species... is a really great thing as far as ongoing management of these sites goes.”
He said the lamington eyebright was known from just five individual plants recorded in 1980, while the green waxberry was known from a similarly small number of plants.
In the latest survey, botanists found about 1000 green waxberry plants and 94 lamington eyebrights.
Mr Mallee said it had been difficult to find out more about the species when there were just a few specimens present.
Bolstered population numbers would also mean the species had more hope for the future.
"Having a larger (population) gives them a much greater chance of long-term survival,” he said.
But with these plants known to exist only on one cliff-face of the Limpinwood Nature Reserve - and nowhere else in the world - Mr Mallee said environmental fluctuations, such as those caused by climate change, were the species' biggest threat.
He said the location's high altitude and constant moisture meant it was perfect for the plants.
If the rainfall in the area was to significantly decrease, however, it could be fatal for the species.
"When you've only got one population of something and the environment changes... it can devastate a species,” he said.
While there will be ongoing monitoring of the plants, Mr Mallee said they had to avoid surveying the mossy cliff more than necessary to minimise disruption.
He said the botanists had abseiled in the reserve with a conservation permit and urged the public to avoid threatening the populations to help strengthen their chance of survival well into the future.
"The main thing people could do is just to remain on dedicated walking tracks when walking within national parks,” he said.
He also urged people to plant native species in their gardens.
"If people plant local native species, it reduces the impact they're having on the environment,” he said.
The wollumbin dogwood was also found during the survey. While it exists in other Border Ranges areas, 182 plants were found on the Limpinwood cliffs.