We’ve seen a lot of yews in a lot of churchyards over the years. I’m going to show you some footage of yew trees while I tell you a bit about them.
The yew is a species of evergreen tree native to much of Europe, including Britain and Ireland. The word “Yew” derives from an ancient proto-Germanic language, which in Welsh became “ywen”.
Yew trees are long-lived to say the least. Trees routinely live past 400 years and there are examples of yew trees as old as 5000 years. That said, yews can be notoriously difficult to date, since the core of the tree can be lost, even as the tree keeps on living.
Yews have had a religious significance for thousands of years. For the Celts, they symbolized immortality. Because the early Christians often built their churches over the top of pagan sites, yews began to be associated with Christian beliefs too, specifically the Resurrection of Jesus Christ, since the same tree can be reborn from a new shoot. According to one Welsh chronicle, before the 5th century, the space between a yew and the church was as sacred as the interior of the church itself. Yews can be found in churchyards throughout Europe to this day.
The link to a Celtic past is not the only theory as to why yew trees are associated with churchyards.
For example, on a practical level, the Welsh are said to have planted yews in churchyards to protect the yews as a source of bow staves. Churchyards protected the yews because 1) the dead bodies provided nutrients to the trees; 2) marauders might burn a village but they’d leave the church alone, thus ensuring the survival of the yews; 3) because churchyards are surrounded by walls, yew seedlings would be protected from roaming sheep and cattle; and 4) roaming sheep and cattle would be protected from the yews, since most parts of a yew tree are poisonous to animals and humans.
By contrast, another theory posits nearly the exact opposite idea: yews were planted in churchyards by priests to protect graves from roaming farm animals. If the beasts came into the churchyard to dig up the graves, they would eat the berries or another part of the yew tree and die.
Another polar opposite theory states that the trees were planted in churchyards to protect and purify the bodies of plague victims.
Finally, we have medieval laws protecting yews. The first is from the Welsh Laws of Hywel Dda of the 10th century, which established a system of fines for cutting down ywen sant or saints’ yews. The second was in 1307. King Edward I established a statute, that was a reiteration of a previous rule by the Synod of Exeter of 1287, forbidding the cutting of trees in a churchyard in order to protect the church itself from gale-force winds.
In the end, nobody knows the real reason yews began to be associated with religion or churches, only that they are!
You make it sound like Welsh is a descendant of Proto-Germanic, which it is not. However, English yew and Welsh ywen are both descendants of a Proto-Indo-European root reconstructed as *h?eyHw- (the capital “H” means that we cannot tell exactly which consonant this is). There has been a good deal of variation in meaning over the past 6000 years: in the Slavic languages the descendant words mean ‘willow’, in Latvian and Lithuanian ‘bird cherry’, in Ancient Greek ‘service tree’, and in the Romance languages and in Armenian ‘grape, bunch of grapes, grapevine’.