IT’S one of the most famous trees in Scotland, a yew so old that Pontius Pilate was said to have played under its leaves during his supposed childhood in Scotland more than 2,000 years ago.

Now the Fortingall Yew in Perthshire has stunned the scientific world by appearing to change sex for the first time in its long life. Some experts say the yew, which is sited in the grounds of Fortingall Church, is Britain’s oldest tree and could be up to 5,000 years old.

The Fortingall Yew is also said be one of the oldest living things in Europe, and though its link to Pilate, the Roman Governor of Judea who ordered the execution of Jesus Christ, is extremely tenuous, there are many legends that connect to it.

Having been at the centre of Fortingall life for centuries, it was always considered a "male" yew of the species Taxus baccata as it produced pollen rather than berries, which are the sign of a female tree and which are evident during the winter months.

Researchers from the Royal Botanic Garden in Edinburgh spotted the switch the Fortingall Yew appears to be making.

Dr Max Coleman, science communicator at the Royal Botanic Garden Edinburgh, discovered the three red berries on the tree.

He said: “Yews are normally either male or female and in autumn and winter sexing yews is generally easy.

“Males have small spherical structures that release clouds of pollen when they mature. Females hold bright red berries from autumn into winter.

“It was, therefore, quite a surprise to me to find a group of three ripe red berries on the Fortingall Yew when the rest of the tree was clearly male.”

When it was measured in 1769 the Fortingall Yew was reported to be up to 5,000 years old, but more recent estimates suggest it could be between 2,000 and 3,000 years old.

The tree’s trunk was once 52ft thick, but it has split into several separate stems, which have broken the rings that would establish its age for certain.

The Royal Botanic Garden is currently engaged in a conservation project for yews, which are widespread across Europe, and the three berries are now being examined as part of that programme.

One expert told The National that having seen the sex change in only a few yews, he was now unsure as to whether such a switch was more common than previously thought.

Dr Coleman hinted that might be possible. “Odd as it may seem, yews, and many other conifers that have separate sexes, have been observed to switch sex," he said. “Normally this switch occurs on part of the crown, rather than the entire tree, changing sex.

“In the Fortingall Yew it seems that one small branch in the outer part of the crown has switched and now behaves as female.

“It’s thought that there’s a shift in the balance of hormone-like compounds that will cause this sex change. One of the things that might be triggering it is environmental stress.”

The Fortingall Yew will now be kept under observation in order to see whether the change of sex proceeds throughout the entire tree.