How was Lincoln green produced using luteolin and indigo?

Lincoln green was produced by combining the yellow crystalline pigment luteolin with indigo, a blue dyestuff.1

Luteolin is a member of the flavonoid family, which occurs in higher plants and is capable of producing various colors, though not green on its own. By mixing this yellow dye with the blue of indigo, craftsmen were able to create the moderate olive green shade historically associated with Robin Hood and his followers.12

Historically, the application of such natural dyes often required the use of mordants—typically metal salts like alum, iron, copper, or tin—to help the dye adhere to textile fibers and to achieve specific color variations.3