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The Fortingall Yew Tree is changing its sex after 5,000 years, in a mind-boggling move which has left some scientists scrambling for an explanation.
The tree, located in the middle of a churchyard in Perthshire, Scotland is actually the oldest in Britain, its existence spanning across 5 millennia so far.
Up until recently, the woody plant had been male, sporting small spheres which released pollen as they reached maturity. Female species on the other hand would normally have bright red berries between autumn and winter.
In October however, Dr. Max Coleman, science communicator at the Royal Botanic Garden Edinburgh, made a staggering discovery: the yew tree had a small branch with a cluster of three ripe red berries. Therefore, while the largest portion of the tree had remained male, a part of it was beginning to switch its sex.
According to the researcher, this behavior, although it might seem completely astounding, has been encountered before among yew trees and other conifers which have distinct sexes. Dioecious plants such as conifers or flowering shrubs have either male plants, which are used for pollination, or female plants, which are employed for bearing fruit.
Sometimes, there are male flowers on female plants or the other way round, but this transformation takes place at the crown, and doesn’t involve the entire plant.
The Fortingall Yew Tree also follows this pattern, because the berries are only found on a bough at the outer part of the crown. However, what’s striking is that this behavior has been identified in such an ancient plant.
One theory is that this is actually a “sport”, or a morphologically distinct growth, but that would’ve made the foliage or flowers different as well. Other speculations are that the tree probably has a hormonal imbalance which causes its male flowers to produce berries, or that it is all a reaction to external sources of stress such as pollution.
It’s also likely that the process actually began as early as 20 years ago, because an eyewitness is alleged to have seen a female branch in the Fortingall Yew back in 1996.
While the female berries might eventually spread, researchers believe it’s improbable that the whole tree would turn female. Such a radical change would put the ancient plant under too much strain, since female trees usually need a higher quantity of nutrients and water than their male counterparts.
Although this discovery has triggered a wave of exhilaration and awe among horticulturists, Dr. Andrew Cameron, Senior Lecturer in Forestry at the University of Aberdeen, believes this recent happening isn’t that astounding after all.
In fact, sex switching occurs in several plant species, sometimes as a result of different stages of growth, which are marked by specific flowering preferences. For instance, younger plants tend to produce a male flower at first, but as the tree gets older and larger this pattern is modified.
So far, three seed samples have been collected from the unusual conifer, and will become part of a project for the preservation of genetic diversity among yew trees.
Image Source: Geograph.org.uk
