The Sussex gardens that are taking a leading role in saving the world's plants ...

In a major report last week, the Royal Botanic Gardens at Kew, revealed that 21 per cent of the world’s plants are now at risk.

And Wakehurst, the country arm of Kew near Haywards Heath, has now launched a new ‘Vital Signs’ trail at its Ardingly gardens to highlight the prognosis of some of the plants affected.

Each of the plants included is marked with a sign which not only gives background information about the plants and the work that Kew and the scientists at the Millennium Seed Bank at Wakehurst are doing to help conserve it, but also carries a thermometer giving an indicator as to whether the plant is of least concern, critically endangered or extinct in the wild.

One of the plants included in the trail is the Franklinia alatamaha – or the Franklin tree - which is the rarest tree at Wakehurst.

It is now ‘extinct in the wild’ and has been since 1803.

Seeds sent to the Millennium Seed Bank were found not to be viable and Wakehurst staff have been trying to pollinate them by hand, but as yet without success.

A Wakehurst spokesman said: “Plants and fungi are essential for human wellbeing; they provide us with food, medicine, fibres, fuel, building materials and many other products as well as holding great cultural meaning for people all over the world.”

At the other end of the scale to the rare Franklin tree is the Magnolia grandiflora or Southern magnolia which is deemed to be of ‘least concern’ in conservation terms inKew’s State of the World’s Plants report.

“But,” said the spokesman: “It is our job to ensure that even plants that grow to great fanfare in abundance do not slip further down the list.

“The seeds of the Magnolia grandiflora are safely stored in the Millennium Seed Bank.”

Wakehurst itself is a National Trust property but funded and managed by Kew.