mygoodbabushka:

Some thorn lore: In Herefordshire, England, to prevent damage to a wheat
crop as the wheat is sprouting, a large thorn bush would be partially
burnt in the field before daybreak. The remainder of the thorn bush was
then hung in the farmhouse. Thorns were believed to ward off witches and
evil spirits. Thorny branches were also laid on the thresholds of barns
of Walpurgis Night (April 30) to keep disease from the animals. Ancient
Athenians chewed buckthorn one morning of the year to banish the evil
spirits of the dead.