The blackthorn had a strong reputation as a tree of witchcraft and cursing: the black rod or blackthorn staff, the shillelagh of Irish tradition, was both a formidable cudgel and, in the darker lore, the wand with which a witch was said to blast and curse, its long hard thorns used to pierce images in ill-wishing. Its thorns cause wounds that fester, which lent the tree a genuine air of menace. Yet the same hedge-thorn gave the protective, impenetrable field-boundary and the loved sloe of the countryside. Winter, hardship, cursing and protection gather to the black-barked, white-flowered, cruelly spined shrub, the dark counterpart of the gentle hawthorn.
In some regional Christian folk tradition, blackthorn rather than hawthorn was named as the wood of Christ's crown of thorns, one of several thorny plants, including also the boxthorn and the Christ's-thorn jujube of the Near East, proposed at different times and places for the crown, a case where popular piety attached a specific real plant to a detail the Gospels themselves leave unspecified. Whichever thorn is meant, the association added a further, specifically Christian layer of suffering to a shrub already carrying an older reputation for winter, hardship and the uncanny.