II) Yew used as a poison

In De Bello Gallico, Caesar reports that Catuvolcus, King of the Eburones tribe, poisoned himself with yew, preferring death to surrender to the Romans:

‘Catuvolcus, rex dimidiae partis Eburonum, qui una cum Ambiorige consilium inierat, aetate iam confectus, cum laborem aut belli aut fugae ferre non posset, omnibus precibus detestatus Ambiorigem, qui eius consilii auctor fuisset, taxo, cuius magna in Gallia Germaniaque copia est, se exanimavit.²⁴⁷⁹

Catuvolcus, King of one half of the Eburones, who had entered into the design together with Ambiorix, since, being now worn out by age, he was unable to endure the fatigue either of war or flight, having cursed Ambiorix with every imprecation, as the contriver of that measure, destroyed himself with the juice of the yew-tree, of which there is great abundance in Gaul and Germany.²⁴⁸⁰ ’

In his Natural History, Pliny the Elder relates that the toxic sap of yew was used in the making of specific ointments applied at the end of the spears or arrows of the Celtic warriors to create lethal weapons, like they did with datura stramonium:

‘Similis his etiamnunc aspectu est, ne quid praetereatur, taxus minime virens gracilisque et tristis ac dira, nullo suco, ex omnibus sola bacifera. mas noxio fructu; letale quippe bacis in Hispania praecipue venenum inest, vasa etiam viatoria ex ea vinis in Gallia facta mortifera fuisse compertum est. hanc Sextius milacem a Graecis vocari dicit et esse in Arcadia tam praesentis veneni, ut qui obdormiant sub ea cibumve capiant moriantur. sunt qui et taxica hinc appellata dicant venena — quae nunc toxica dicimus —, quibus sagittae tinguantur. repertum innoxiam fieri, si in ipsam arborem clavus aereus adigatur.²⁴⁸¹
Not to omit any one of them, the yew is similar to these other trees in general appearance. It is of a colour, however, but slightly approaching to green, and of a slender form; of sombre and ominous aspect, and quite destitute of juice: it is the only one, too, among them all, that bears a berry. In the male tree the fruit is injurious; indeed, in Spain more particularly, the berries contain a deadly poison. It is an ascertained fact that travellers' vessels, made in Gaul of this wood, for the purpose of holding wine, have caused the death of those who used them. Sextius says, that in Greece this tree is known by the name of ‘smilax’, and that in Arcadia it is possessed of so active a poison, that those who sleep beneath it, or even take food there, are sure to meet their death from it. There are authors, also, who assert that the poisons which we call at the present day ‘toxica’, and in which arrows are dipped, were formerly called taxica, from this tree. It has been discovered, also, that these poisonous qualities are quite neutralized by driving a copper nail into the wood of the tree.²⁴⁸² ’