Elder was used in Rome and 11th century Italy for healing. The 17th century herbalist John Evelyn praised the healing virtues of elder in his herbal. Elder leaves, boiled with linseed oil are an old English remedy for wounds and bruises.
It was thought the Elder could not be hit by lightning, and so should be planted near the house. In the sixteenth century it was believed that the leaves of the elder should be gathered on the last day of April, and hung on doors and windows to prevent witches from entering the house. A twig of Elder carried close to the body, was thought to give good health and luck.
The Druids believed that elder was inhabited by the Elder Mother, and the tree was sacred Frau Holle, the "witch goddess". Circle dances were performed around the tree in midsummer at the summer solstice when the elder bloomed, it was associated with the ecstasy of summer love.
Claudia Muller-Ebeling, Wolf-Deieter Storl Witchcraft Medicine(1998)