Shakespeare's Aroint Thee, Witch for the last time?

Aroint thee, an imprecation addressed to a witch, occurs only in Shakespeare and in his later imitators. Its usual gloss in modern books is 'begone', and it seems to have served as a deterrent against witches. There is no compelling reason to classify aroint with verbs. Both Germanic and Romance etymons of aroint have been proposed. None of them sounds convincing, so that dictionaries call aroint a word of unknown or uncertain etymology. Most probably, the formula refers to the rowan tree, famous in myth and folklore for its apotropeic properties. Rowan and its variants are of Scandinavian origin, but, as far as we can judge, the imprecation was coined in England.