The roots are antibacterial, antifungal, and expectorant and are still used in cough medicines. Recent research shows extracts from the plant may be effective against bacteria including MRSA. It has 10" leaves and 2 inch wide yellow flowers; the roots yield a blue dye. Its erect stems are deeply furrowed, and branch near the top. It becomes a huge and spreading plant in rich garden soil, so be sure to give it enough room. Named after Helen of Troy - she was said to be harvesting it when abducted. Dormant October - March.