The woad was a plant cultivated inside a triangle Toulouse - Albi- Castelnaudary. A dye was made: the " blue pastel ". The plant, of its Latin name " Isatis tinctoria " is similar to the family of cabbages, radish, colza, etc.
The perfect blue obtained was the only one, in its time, to resist successive washes.

Known since Antiquity, it could serve, additionally, as food for cattle and we recognize some medicinal virtues.

In the Middle Ages it came into competition with the other dyes

At this time, the development of the art clothing required larger range of plant dyes. The appropriation of various dyes allows a distinction in social classes.

So:
The madder gives a red colouring agent
LThe kermes gives a red scarlet
The gaude produces a green-yellowish color.