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 Europe and Western Asia, 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
This herbaceous biennial plant is 2-5' tall and little branched, except occasionally near the base during the second year. During the first year, this plant consists of a low-growing rosette of basal leaves up to 1' across. These basal leaves are narrowly ovate or oblanceolate and dark green. Their margins are smooth and vertically undulate, sometimes even crinkly-edged, while their upper surface is hairless and shiny. The hairless round stems of plants during the second year have fine longitudinal veins that are dark green. The alternate leaves are up to 5" long and ¾" across, becoming smaller as they ascend the stems. They are narrowly ovate or oblong-linear in shape and more or less sessile against the stems, otherwise their appearance is similar to the basal leaves. The stems terminate in spike-like racemes of yellowish green flowers about ½–2' long. The flowers are densely distributed in all directions along the length of the racemes.
This plant is useful.