The Berberis, originally wild collected in China by Ernest Wilson, has been growing at Trewithen for about 100 years. Unlabelled since 1914, the plant had faded into the background until Chinese Berberis expert Julian Harber, who knew of Trewithen's plant hunting history, came looking for it this summer.

He said: "I was visiting Trewithen whilst on holiday in Cornwall because I knew that George Johnstone who inherited the estate in 1904 was a supporter of seed collecting expeditions. I hoped that there was a possibility that Trewithen might have a Berberis collected during that time."

After meeting with Trewithen's Head Gardener Gary Long, and looking back at George Johnstone's intricate garden record book, Mr Harber was able to find and identify the plant.

By breaking open the seed pods and analysing the plant's structure, Mr Harber has confirmed that Trewithen is definitely the home of what he thinks is the UK's oldest and largest Berberis francisci-ferdinandi. At 15ft high, other known examples in the UK are at Kew Gardens and The Royal Botantical Gardens in Edinburgh.

Gary Long describes the find as very significant. He said: "From my point of view it is always exciting to identify a plant, especially one that has such a history.

Collected from Sichuan China as a seed in 1908 and then planted here, it has been left to grow quite happily with nobody knowing what it was for at least the last 45-50 years. Now it will be treated with extra care, labelled, logged and its seed will be propagated to ensure the survival of the type species."

Trewithen garden is open Monday to Saturday from 10am to 4.30pm until September 30th. Visit the ‘Travelling Trees' Exhibition located in the museum that details the gripping history of the Plant Hunters.