Hemlock

Far away beyond the pine-woods, there is a little garden. There the grass grows long and deep, there are the great white stars of the hemlock flower, there the nightingale sings all night long. All night long he sings, and the cold crystal moon looks down, and the yew-tree spreads out its giant arms over the sleepers.

Source: tatoeba (5420666)

Socrates was sentenced to death by drinking an infusion of poison hemlock.

Source: tatoeba (12101288)

Have a tree or two the witches particularly like, such as the alder, larch, cypress and hemlock; then, to counteract any possible evil effects, there must be a holly, yew, hazel, elder, mountain ash or juniper.

Source: wiktionary

In the Tyrol, on May Day, it was the custom to smoke out witches by burning bundles of black and red spotted hemlock. In the eighteenth century hemlock was used for treating cancer, syphilis, and ulcers.

Source: wiktionary