Blue-dye plants are plants that are used to produce a blue dye. Two of the most common blue-dye plants are Anils and Woads. Anils are a type of flowering plant in the family Fabaceae, native to tropical regions of the Americas. Woads are a species of flowering plant in the family Brassicaceae, native to Europe, North Africa, and western Asia. Both Anils and Woads have been used for centuries to produce a blue dye.