A top-secret plantation of the critically endangered “dinosaur tree” Wollemi pine is flourishing, the New South Wales government says.

The 200-million-year-old pine was presumed extinct and only known in fossils before it was discovered in remote canyons of the Blue Mountains in 1994.

An “insurance plantation” of 191 of the pines was planted in 2012 to secure its survival, in case disease or fire tore through the remaining 100 trees in the wild.

“The top-secret insurance population is now naturally producing cones and seeds, marking an exciting new step towards securing the survival of this ancient iconic plant,” Environment Minister Gabrielle Upton said in a statement on Monday.

“It’s one of the world’s oldest and rarest plants from the time of the dinosaurs.”

She said only four strands of the rare pine were growing in the canyons, making this a “real win for the environment”.

Sir David Attenborough is pictured planting a Wollemi pine at Kew Gardens in London in 2005. Photo: Getty

Cathy Offord – principal research scientist at the Royal Botanic Garden Sydney, who has been studying the pine since its discovery – said the insurance plantation was doing better than those in the wild.

“Some 83 per cent of the insurance Wollemi pines are surviving and have increased in size by up to 37 per cent, making them mature enough to produce potentially viable seed much earlier than expected,” Dr Offord said.

“We’ve now collected around 60 viable seeds, which are being used to find the best way for them to grow on their own.”

Heidi Zimmer, a senior scientist at the Office of Environment and Heritage, said the production of cones “means we’ve got the science right”.

“There is now a strong possibility that this insurance population may become self-sustaining,” Dr Zimmer said.

The government funded the plantation using $200,000 from its Saving Our Species program.

The insurance plantation site was chosen to be some distance from the wild population to reduce the risk of disease or fire impacting both populations.

Wollemi pines were presumed extinct until they were discovered in remote canyons of the Blue Mountains in 1994. Photo: AAP

The plantation is a collaboration between the department, the Royal Botanic Garden Sydney, National Parks and Wildlife Service, Melbourne University and Western Sydney University.

David Noble, a national parks officer, discovered the Wollemi pine in 1994.

The pine, or a very similar relative, was previously only known from fossils, explaining the term “dinosaur tree”.

It’s thought to have evolved 200 million years ago.