The Riddell Ranges estate, off Royal Parade in Riddells Creek, consists of 162 allotments on about 118 hectares.

The estate allotments are owned by 130 landowners, who have never been able to build because of concerns about unstable soil and the land's environmental values.

In 2000, the Macedon Ranges Council launched a lease-back plan inviting owners to lease the land to the council, which it then planned to use to create a number of larger blocks more suited to development.

After nine years, the participation rate in the lease-back plan from landowners has been low.

At a council meeting last week, councillors supported a report that recommended it discontinue the lease and sale scheme when it expires in June next year and work with the State Government on the possibility of acquiring the land for use as flora and fauna reserves.

The council's Natural Environment Strategy 2009-12 proposed investigating creating a flora and fauna reserve in partnership with the State Government and other authorities.

The trigger plant, believed to be found nowhere else in the world, was discovered by Riddells Creek Landcare members Russell Best and David Francis and Victorian senior conservation botanist Neville Walsh while researching a book on the flora of the Barrm Birrm area in Riddells Creek, which is also known as the Riddells Creek Estate.

Listed for protection under Victoria's Flora and Fauna Guarantee Act this year, the hairy-leaved trigger plant has been found only in the Macedon Ranges.

"This is a significant find because it seems to be endemic to the Macedon Ranges area. This means it only occurs in the Macedon Ranges area and nowhere else on the planet. This really is Macedon Ranges' only unique wildlife. It really is something to celebrate," said Dr Best.

Dr Best said the block of land was arguably the most biodiverse block of land in the shire with significant conservation values.

Mr Francis said the landcare group welcomed the council's decision.

"It is all very positive. It seems the council is recognising the area will eventually end up as public land. We want it to become a reserve to add to the other reserves in the area and to be enjoyed by the community," he said.

"It is pristine. You wouldn't imagine that you were so close to Melbourne. It's just like it was 100 years ago."