The Fortingall Yew, Britain's oldest tree, has begun to change its sex. The 5,000-year-old tree, which has always been regarded as male, recently exhibited female-associated features, suggesting the gender change.

Yews are typically male or female in gender. In autumn and winter, sexing these trees is fairly easy. Male yews are characterized by small spherical structures that emit pollens as it reaches maturity. Females, on the other hand, are distinguished through its red berries that occur during autumn and winter.

Close observations deem the Fortingall Yew to be a male; however, experts were baffled when they discovered that it exhibited a clump of three red ripe berries in October 2015, when the rest of the tree still maintained its male characteristics.

Although bizarre-sounding, yews and other conifers known to have different genders, have been noticed to change sex. The said transformation is manifested only on a region of the crown, rather than on the entire tree structure. In the case of the Fortingall Yew, a part of the crown has changed and now functions as a female.

Max Coleman from Royal Botanic Garden Edinburgh said it is rare and not yet completely comprehended. He added that sex change is believed to be triggered by a change in the balance of compounds that resemble hormones. Among the factors initiating such change is environmental stress; however, he said that the tree looks healthy.

The tree would now be monitored closely for other shifts.

The Fortingall Yew is located inside an old church yard. The exact age of the tree is quite challenging to determine because the wood in the center of the tree, known as heartwood, has long decayed already.

Some trees routinely change sex, with some producing male flowers in one year and female fruits in the next. Should female trees give out a massive fruit produce within a year, it may switch to the male gender to rest itself.

"This process may have happened before but we know the Fortingall Yew has been classed as male for hundreds of years through records," said Coleman. "The sex change isn't the amazing bit in this case, it's the fact it's this particular tree."

Photo: Bernt Rostad | Flickr