The precession of the equinoxes has moved the astronomical beginning of spring back four days to March 21, but its previous date of March 25 became identified with the Virgin Mary, who was told by the angel Gabriel on that day that she would become the mother of Christ. Lady Day, as this day was commonly called, was one of the great quarterly dividing points of the year (the others being Midsummer Day, Michaelmas, and Christmas). It was traditionally the day for paying rents, signing or vacating leases, and hiring farm laborers for the year. The flower cardamine, or lady’s-smock, with its milky white flowers, is dedicated to the Virgin Mary and appears about this time. For a discussion about this plant’s significance, go to this site.