The oldest tree in the United Kingdom — possible among the oldest in all of Europe — has surprised experts by showing signs of a sex change from pollen-releasing male tree to berry-producing female.
The 5,000-year-old tree in Scotland known as the "Fortingall Yew" and identified for centuries as male has suddenly sprouted berries, which only female yews produce, on one of its branches, the Royal Botanic Garden in Edinburgh reported,
"I was very surprised to see a few berries on what was clearly otherwise a male tree," said Dr. Max Coleman, a science communicator at the botanical gardens.
Although rare, sex changes of this type are not unknown in the tree world, he says.
"Some trees, like ash, can routinely change sex. Others, like yew, do this very rarely. We don't fully understand why, but it probably has to do with maximizing the chances of reproduction and could be in response to environmental triggers, age or simply pure chance."
While many species of tree contain both male and female parts, yew trees are dioecious, meaning any individual tree will be either male or female.
However, sex changes can happen if there a change in the levels of a tree's growth hormones, experts say.
Still, Coleman says, it's a "rare occurrence."
In the case of the ancient yew, which lives behind a small stone walled enclosure in a churchyard in the Perthshire village of Fortingall, the sex change of at least a small part of its branches may be a tactic meant to prolong its life.
"The Fortingall Yew is fragmented and it may be so compartmentalized that part of it has become sexually ambiguous," said Ancient Tree Forum chairman Brian Muelaner. "We are all continuously learning about ancient trees — the aging process of trees is a new science."
Three berries have been picked from the female branch producing them and have been planted in pots. According to experts, if they germinate with the coming of spring, they would be the first identifiable offspring of the Fortingall Yew in thousands of years.
Despite its great age the tree appears to be in good health.
It may be the oldest living tree in all of Europe, although its true age is impossible to determine exactly since many of its most ancient portions have decayed and disappeared.
Photo: Bernt Rostad | Flickr
