During the ceremonies of initiation into the Ancient Mysteries, it is supposed that the neophyte left the physical body in a trance state, and in full consciousness, which he retained afterwards, entered the subjective world and beheld all its wonders and inhabitants; and that coming out of that world he was clothed in a robe of sacred green to symbolize his own spiritual resurrection and re-birth into real life — for he had penetrated the Mystery of Death and was now an initiate. – Walter Y. Evans Wentz
Green clothes are worn in the United States, but not in Ireland because of the upsetting reminder. Today the seamróg joins the English Rose and the Scottish Thistle on the British flag and is an integral part of Saint Patricks Day celebrations. (1, 2, 4)