Woad is also known as Isatis. This is Dyers Woad, source of a natural blue dye used iand Europe since medieval times. Herb also has an antiviral action, being used in Ayurvedic medicine for immune system support and treatment of urinary tract infections. Woad is native to Europe and Asia, being adaptable to most soils and positions. Frost and drought tolerant. Herbaceous perennial to 1.2m. Bright yellow flowers in spring and summer.