Which plants provided natural yellow dyes such as luteolin and quercetin?

Natural yellow dyes such as luteolin and quercetin are derived from specific plant sources:

• Luteolin: This yellow pigment is obtained from the leaves of the weld plant, Reseda luteola. Historically, it was often combined with indigo to create "Lincoln green," a color famously associated with the legend of Robin Hood.1
• Quercetin: This compound is found in the bark of the North American oak tree, Quercus tinctoria. It is also a primary component of quercitron bark, which comes from the inner bark of the black oak, Quercus velutina.12

Both luteolin and quercetin belong to the flavonoid family, a group of water-soluble phenolic compounds that are widely distributed in higher plants and responsible for many of the yellow and ivory pigments found in nature.13