Isatis tinctoria

Species of flowering plant

Isatis tinctoria, also called woad, dyer's woad, dyer's-weed, or glastum, is a flowering plant in the family Brassicaceae (the mustard family) with a documented history of use as a blue dye and medicinal plant. The double use of woad is seen in its name: the term Isatis is linked to its ancient use to treat wounds; the term tinctoria references its use as a dye. It is occasionally known as Asp of Jerusalem.

From Wikipedia, under CC BY-SA. More on occurri.