"Mountain ash, 1804, from rowan-tree, rountree (1548), northern English and Scottish, from a Scandinavian source (cf. O.N. reynir, Swed. Ronn "the rowan"), ultimately from the root of red, in reference to the berries. The rowan "was the tree most often credited with protective magical powers against all effects of witchcraft, not merely in Celtic areas but throughout Britain." -- Oxford Dictionary of English Folklore


