Judas Iscariot was one of Christ's twelve apostles. He appears in the Gospels of Matthew, Mark, Luke and John, and is the one to betray Jesus to the authorites. The High Priest Caiaphas was determined to kill Jesus and persuades Judas to identify him with a kiss, in exchange for thirty pieces of silver. Accounts of Judas' subsequent death differ, but in Western culture he is typically shown as committing suicide by hanging from a tree. In Dante's 'Inferno', he is shown in the ninth and most terrible circle of Hell, reserved for traitors, where his punishment is to be chewed in one of the mouths of Satan for eternity.
The Elder tree grows throughout the world, but thrives especially well in the Northern Hemisphere. Its berries can be eaten when ripened, and it is also the source of elderflower cordial. The belief that Judas used this tree to hang himself originated in the Middle Ages; it has also attracted a number of other superstitions. In some places, it was thought that if you burned elder wood the devil would appear, whereas in other areas people believed that having an Elder tree outside your home gave protection from witches and evil spirits.