One of Europe's oldest surviving organisms is having a "sex change"—and growing pretty red berries to boot. A yew tree in Scotland that's thousands of years old has grown three seed-bearing berries, marking it as "female" for the first time on record, the Guardian reports. "Yews are normally either male or female and in autumn and winter sexing yews is generally easy," writes botanist Max Coleman in a blog for the Royal Botanic Garden Edinburgh, where the Fortingall Yew lives in a stone enclosure. "Males have small spherical structures that release clouds of pollen when they mature. Females hold bright red berries from autumn into winter." He says it was "quite a surprise to me" to discover the berries, each of which contains a single seed.
Turns out it's not that strange: Yews and other conifers are known to change sex "on part of the crown," explains Coleman. "In the Fortingall Yew it seems that one small branch in the outer part of the crown" has changed after the tree was male "for hundreds of years." So why the switch? It's usually caused by "a shift in the balance of hormone-like compounds," he tells AFP, but "one of the things that might be triggering it is environmental stress." Now botanists have sown the three seeds in the botanic garden to preserve the genetic diversity of yew trees. As for the Fortingall Yew, it's hard to date exactly because its growth rings have rotted, but estimates put it between 2,000 and 5,000 years old, the BBC reports. It lives behind an enclosure to prevent "souvenir hunters" from "help[ing] themselves to parts of the tree," writes Coleman.