The status of the Wollemi pine is set to be elevated to critically endangered because of threats by a root mould and because there are so few specimens left in the wild.
The pine, discovered in the greater Blue Mountains area 21 years ago, was reviewed by the NSW Scientific Committee after the International Union for the Conservation of Nature listed it as critical.
The NSW committee has recommended the highest level of endangered status because it is so susceptible to Phytophthera cinnamomi, a pathogen which causes dieback of branches and stems.
While no individual trees have died from it, there is no comprehensive control to treat it, although scientists are experimenting with injecting a fungicide into infected trees.
There are also fewer than 100 mature individuals in the wild and fewer than 300 juvenile plants.
The listing recognises that the Wollemi pine faces an extremely high risk of extinction in NSW in the immediate future.
Blackheathan and former national parks worker Wyn Jones, who named the pine (with Jan Allen from the Botanic Gardens), said the upgraded listing was "not unexpected".
"They have known about phytophthera for a long while and they can't really do much about it," he said.
"I'm really glad they have taken action to put it on the critically endangered list. I think it's really important they do that because it alerts people and hopefully it will lead to research into phytophthera."
Mr Jones said he hoped scientific visits to the site would be "restricted to an absolute minimum" to prevent further spread of the mould but said there were other ways the virus could get into the area, including through animals and from run-off from surrounding land.
The Wollemi pine was thought to have been extinct for two million years until a chance discovery in 1994 by national parks officer and keen bushwalker David Noble. He brought a sample of the strange plant with its trunk resembling Coco Pops back to his office in Blackheath. Mr Jones and Ms Allen later named it Wollemi nobilis, after the place where it was found and Mr Noble.
The plant has been propagated both for nursery sales and for replanting at other sites in the wild.
