All parts are medicinal, although it is the root that is most often used. Immune stimulant for colds and flu. Also makes a great cut flower and bee food. Harvest roots and after 3 years but stems and flowers from second year. The purple coneflower is a perennial wildly used in herbal medicine. It stimulates the immune system and an infusion of the plant was also used by native North American tribes to treat snakebites and insect stings.