supposed to be 5000 years old
Personally, I'm skeptical based on other old trees I'm familar with and am inclined towards the more prevalent 2000-3000 year estimate. The basic argument for 1500 years (germination after construction rather than construction around an existing tree) doesn't seem a bad one either, but this probably isn't the sort of thing which will get proved one way or the other.
It is producing berries on a branch which is not uncommon with yews.
Well, botanically, arils and berries are different things. So, technically, a berry producing
Taxus would be rather uncommon.
But, yeah, dioecious to monecious flowering is a continuum and plant totipotence and indeterminate growth mean sex is less of a identity thing than it is for species with deterministic growth. Individuals of some dioecious tree species are also documented as changing between staminate and pistillate flowers every few years. Other species will switch from female to male in response to low fertilization success.
the needles in the foreground are very distinctive of this species
I'd deferred some caveats about this. The falcate shape, decurrence producing green stems to the previous node, and 2-ranked appearance are distinctive of
Taxus, which is how I immediately recognized the Fortingall Yew as a yew (from there it was the fifth hit on an image search for "old yew"). The points at the end of the needles are characteristic of the Taxaceae family (the next level up from genus taxonomically) and are diagnostic in distinguishing Taxaceae from Pinaceae and Cupressaceae but they're not visible in the photograph here.
Cardiotoxicity of yew (Taxus baccata)
Yes, that's one of the papers I pulled. The statement in its abstract is "taxine alkaloids contained in yew berries, needles or bark are poisonous", which is distinct from saying all parts of the tree are toxic. It's also either poorly written or partially incorrect since 1) yews do not have berries in a scientific sense, and 2) while the seeds are toxic the arils do not appear to be indicated as such (
Earle). Similarly, Grobosch 2013 (the second link) indicates leaf ingestion but not ingestion of other parts of the tree.
I didn't see anything indicating toxicity of the wood (xylem), which suggests most of the biomass in any
Taxus individual is probably not toxic. This is consistent with taxine production as a defense compound to inhibit bark degrading fungi (
Talbot 2015) and the apparent lack of handling concerns with longbows. The literature also suggests toxicity varies among
Taxus species. Reported details are conflicting, but production in
Taxus brevifolia appears negligible to low and relatively high in
Taxus chinensis.
. So I'll pass on this one.
