Reseda luteola grows 2 to 5 feet tall and produces slender racemes of small, yellowish-green flowers in spring. It is a biennial, forming a low rosette in its first year before sending up flowering stems in the second. The species epithet luteola is Latin for "yellowish," a reference to the intense golden dye extracted from the stems, leaves, and flowers. That dye, luteolin, bonds exceptionally well to wool and silk and produces shades ranging from bright chartreuse to deep olive depending on the mordant used. The plant is native to Europe, western Asia, and North Africa and has naturalized across the Americas and Australia, where it is classified as invasive.

In the garden, weld asks very little: full sun, poor to average soil with decent drainage, and absolutely no fertilizer. It resents transplanting, so seed should be sown directly where the plants will grow. Seeds require light to germinate, so press them gently onto the surface rather than burying them. Butterflies visit the flowers readily. It can self-seed aggressively where conditions suit it, so deadhead after flowering if the garden needs a firm hand. For dyers and historically minded growers this is a plant of genuine substance, even if its appearance never quite matches its chemistry.