How Old is That Yew? – Age Categories Used by SYTHI

 

Since time immemorial individual trees have been described as ancient and are often found featuring in myth, legend, literature, folklore and botanical science. This epithet of ‘ancient’ as a figure of speech has no explicit or scientific explanation as to how many years is meant by the term. It is intended to instil a sense of awe – often spiritual awe – that the origin of an ancient tree was centuries back in the mists of time.

For people living not that long ago in Scotland, often with an average life expectancy half that of today, their perception of a few hundred years could mean an almost unimaginable long time. What then would it have been like for them trying to imagine 1,000 or 2,000 years ago, and the yew tree they saw before them had lived for such a vast time period? It is incredibly difficult to imagine even today but we have reliable history and prehistory to help us put such time scales in context, a facility unavailable to our distant forebears.

An example of yews age classified as Heritage, at Scone Palace
An example of yews age classified as Heritage, at Scone Palace

In the 18th century botanists began to realise that growth increments of trees (‘rings’) revealed when a tree was felled could be counted and provide an accurate age estimate for it, as well as ascertaining growth rates of the tree over time. The number and width of the rings in any given species could then be used to estimate the age of other trees of that species without any felling involved. This is normally straightforward in most trees but not the yew, and obviously if a yew is hollow there is no wood to count rings.

An example of an ancient yew - Glamis castle
An example of an ancient yew – Glamis castle

Botanists such as Augustin Pyramus de Candolle (1778 – 1841) who pioneered the dating of trees, claimed by his methods to have found yews 2,000 years old and more in Britain, though his claims have been a bone of contention since. Nevertheless, the core elements of his work means he is respected as being one of the founders of the modern science of dendrochronology (tree ring dating) which has all kinds of hugely significant historical and archaeological applications in increasing understanding of history.

In 1994 a Gazetteer of ancient yews was published in the book The Sacred Yew (Chetan and Brueton, Penguin Arcana). In 404 entries, only two were listed as being less than 1,000 years old and some 2,000, 3,000 years and even more. Hence a classification of what was an ancient yew became 1,000 years by default. But what about significant yews 300, 600 or 800 years old, and the obvious difference in importance if a yew may be 1,000 or 2,000 years old?

Ormiston Yew
Under the canopy of the vast Great Yew of Ormiston, known as a famous landmark tree 500 years ago Yew – Ancient Plus

We should bear in mind that many trees such as ash, beech or birch normally do not reach 300 years old. Others can become much older such as lime, oak, sweet chestnut and Scot’s pine but generally in these species it is not the norm to have the capability to live for over 1000 years, but every yew tree begins its life with that capability. At 300 years old a yew tree is typically passing from a juvenile to mature stage and between 300 – 400 years of age hollowing of the trunk can begin. Therefore when we categorise a yew as ancient we have a conundrum because 400 years old or more, in the potential lifetime of a yew, is not ancient as measured in yew life expectancy. A rough equivalent would be a person in their mid-teens, obviously with a long way to go before being considered ancient.

The Fortingall yew has been the subject of much debate over it's age
The Exceptional Great Yew of Glen Lyon at Fortingall, and what is left of it today. Most opinions in yew research agree it is probably over 2000 years old, while some think much older.

In 2010, Toby Hindson of the Ancient Yew Group, greatly improved the age classifications taking into account not only girth measurements (ideally regularly recorded over time) but also physical condition (e.g. hollow or not, fragmented or multiple trunks) and if significant historical factors applied to the location. To simplify matters for our purposes here, the categories became Notable (300 – 500 years) Veteran (500 – 800) Ancient (800 – 1200) and Exceptional (1200 plus with no upper age limit). The AYG is obviously not the only interest in recording and archiving ancient trees in the UK and Ireland. AYG affiliated organisations such as the Tree Register of Great Britain and Ireland, Ancient Tree Forum, Ancient Tree Hunt, Woodland Trust and Forestry Commission amongst many others applied different categories which made matters confusing when sharing data about yews.

To resolve this, in recent years the Forestry Commission definition of ancient (planted or naturally growing since before 1600) has been adopted and any yews 400 years old or more are now classified as ancient. If that does not seem like a long time ago, let us bear in mind it was when James the Fourth  was on the throne of Scotland and a century before the Act of Union in 1707.

Age Categories Used by SYTHI

As SYTHI is a yew specific project linked to the AYG, the main categories have been adapted to reflect the nature of the yew heritage of Scotland and hopefully make them as simple as possible to understand.

Any yews less than 400 years old are also very significant and are obviously the majority classification in Scotland’s yew heritage. Of course, if they are respected and cared for, they will become ancient in time. Mostly, Heritage yews are of tremendous historical and cultural significance, such as they were planted, or were noted and remarked upon, or inspired people and organisations embedded in the fabric of Scottish history over the last 400 years (see Wemyss Mausoleum and Rosslyn Chapel site entries).

The number of ancient yew sites in Scotland as now classified in SYTHI data is over 50 and many more than when known Scottish recorded sites were categorised 10 years ago. However, in many cases the AYG data on recorded sites accumulated mainly from affiliated sources, such as the Ancient Tree Forum, is over 10 years old and sometimes 20 years or more. Hence a primary aim of SYTHI is to confirm, update and re-categorize these recorded sites