One subspecies blooms at the abbey in England believed by some to have been established by St. Thomas. There is a source that claims it blooms near the new calendar date of January 6. This date had been Christmas day under the old Julian calendar. So when Christmas day under the new calendar came around and the flower did not bloom, it was such a frightful omen that England did not adopt the Gregorian calendar at that time in 1588; adoption had to wait until 1751.
In the Middle Ages, people strewed the flowers on the floors of their homes to drive out evil influences. They blessed their animals with it and used it to ward off the power of witches. These same people believed, however, that witches employed the herb in their spells and that sorcerers tossed the powdered herb into the air aruond them to make themselves invisible.