Isatis tinctoria aka Dyer's Woad

Isatis tinctoria, also known as woad, dyer's woad, or glastum, is a short-lived perennial or biennial plant in the family Brassicaceae that is native to Europe and southwestern Asia. It features basal rosettes of stalked, oblong-lanceolate, gray-green leaves and stalkless, smaller, alternate, arrow-shaped, gray-green leaves. In the second year, branched, alternate-leaved flowering spikes rise above the basal rosette to 2-4’ tall, producing four-petaled yellow flowers that bloom in early summer in loose 3-inch long racemes which collectively form a large terminal panicle. The flowers are followed by dark, pendant decorative seed pods. Woad is also the name of a blue dye produced from the foliage of the plant, which has been used for centuries. The genus name, Isatis, derives from the ancient Greek word for the plant, ἰσάτις, and the term tinctoria references its use as a dye. In medieval times, there were important woad-growing regions in England, Germany, and France, and towns such as Toulouse became prosperous from the woad trade. While woad was eventually replaced by the more colorfast Indigofera tinctoria and, in the early 20th century, both woad and Indigofera tinctoria were replaced by synthetic blue dyes, there has been some revival of the use of woad for craft purposes. Woad has also been used medicinally for centuries, with the term Isatis linked to its ancient use to treat wounds. In addition to its traditional uses, woad is also a rare houseplant that is not challenging to grow and prefers long-lasting, direct light and regular watering to thrive.