Isatis Tinctoria

This famous plant makes a dividing clump of shiny leaves, above which arise masses of small yellow flowers which in turn produce sprays of unusual elongated seeds. This is the plant made famous as the source of the most important blue natural dye, used by the Celts, the ancient people of the British Isles (& Braveheart!). The leaves must be dried and then steeped and fermented in water to produce a deep blue dye that is useful for ruining your clothes, or maybe painting your face blue to frighten visitors............