Scotland – The Fortingall Yew tree in Scotland, one of the oldest and most famous trees in Europe, has decided to change its sex.

The tree, that is thought to be between 3,000 and 9,000 years old, was a male specimen, although new characteristics showed in its branches suggests that it is becoming a female yew tree.

The tree has been male for thousand of years, however, it is now doing something only a female can do: sprout berries. Credit: Mogens Engelund/Wikimedia

Although is rather difficult to estimate its age, due to the fact that several parts of the tree have decay with the passing time, scientists believe that the tree has around 5,000 years old, by comparing its current trunk size with measures taken in 1769.

Max Coleman, of the Royal Botanic Garden in Edinburgh, noticed the recent changes on the tree. The yew trees family are dioecious, meaning they are either male or female. This responds to a behavior showed in these and other dioecious trees that allow the species to produce larger fruits and better seeds.

The Fortingall yew tree, being male, was a sprawling tree, producing spherical structures that release pollen. Female yews, on the other hand, produce the well-known bright red berries. That’s how Max Coleman noticed the sex-change, by observing red berries on the Fortingall yew tree.

“Odd as it may seem, yews, and many other conifers that have separate sexes, have been observed to switch sex. Normally, this switch occurs on the part of the crown, rather than the entire tree changing sex,” wrote Coleman on his blog.

A similar phenomenon was recorded by a botanist in 1837, registering a partial sex-change on a yew tree in Shropshire, although experts say that this is extremely unusual to happen. Moreover, what’s behind these changes is something that scientists don’t understand quite yet. Nevertheless, Dr. Coleman and his colleagues believe that this sex change may respond to environmental factors, or to a tactic that the tree is applying to prolong its life.

Brian Muelaner, chair of the Ancient Tree Forum, supports this “longevity” theory, saying that the Fortingall yew is currently fragmented, explaining why it could be sexually ambiguous, according to The Guardian.

Coleman compared his observations with the ones made in 1996 by a women called Janis Fry, that had spotted a female branch on the Fortingall Yew, providing evidence that the sex-change could have been happening for the last 20 years.

Although the Fortingall yew tree is very old, it appears to be healthy enough to maintain this sexually ambiguous lifestyle for a few more years. Coleman and his research team will continue observing and studying this old tree behavior, located in the Highland Perthshire village of Fortingall, eight miles west of Aberfeldy.

Coleman reported that he picked some berries off the tree and put them into pots so they can germinate. If this happens next spring, the Fortingall yew will produce its first offspring ever.

Source: Royal Botanic Garden Edinburgh