Blessed Thistle is associated with purification and protection, placed on an altar by itself and especially with other sacred herbs such as Yerba Santa and Angelica root, it is said to aid to bringing spiritual assistance into the home.
It is also believed that wearing a bit of it would protect one from evil. Further, it is associated with the planet Mars, the zodiac sign of Aries and the element Fire. It is also highly recommended in purification baths.
Blessed Thistle is also known as Holy Thistle or St. Benedict's Thistle and was grown in the gardens of monks.