Weld or Dyer's Rocket (Reseda luteola) is a plant native to the Mediterranean. Yellow dye was obtained from the roots by the first millennium BC, and perhaps earlier than either woad or madder. I'm trying to find some here on Milos but no luck so far!
Madder, the Maddermarket in Norwich is were the crop was bought and sold. The boiled root produced madder rose, or Norwich red, as a pigment for dyes. Used also by medieval painters in retables at the Cathedral.