Reseda luteola 黄木犀草
Reseda luteola is a plant species in the genus Reseda. Common names include dyer's rocket, dyer's weed, weld, woold, and yellow weed. A native of Eurasia, the plant can be found in North America as an introduced species and common weed.
While other resedas were used for the purpose, this species was the most widely used source of the natural dye known as weld. The plant is rich in luteolin, a flavonoid which produces a bright yellow dye. The yellow could be mixed with the blue from woad (Isatis tinctoria) to produce greens such as Lincoln green. The dye was in use by the first millennium BC, and perhaps earlier than either woad or madder. Use of this dye came to an end at the beginning of the twentieth century, when cheaper synthetic yellow dyes came into use. France exported large quantities of weld.