Isatis tinctoria is a biennial member of the mustard family that can grow from 1-4 ft. (0.3-1.2 m) tall.
Foliage
First years growth is represented by a rosette of hairy, bluish-green leaves 1.5-7 in. (3.7-18 cm) long. Stem leaves are lance-shaped and alternate with a cream colored mid-rib.
Flowers
Flat-topped yellow flowers with four spoon shaped petals appear in small clusters at the top of the stems. Flowering occurs in spring to late summer.
Fruit
Seed pods are black or purplish, flattened, 0.4 in. (0.9 cm) long, 0.25 in. (0.6 cm) wide and hang from short stalks at the ends of the stems.
Ecological Threat
Isatis tinctoria occurs in areas with poor, dry soils such as roadsides, rangelands and open forests. Isatis tinctoria is native to central Asia and northern Russia and was introduced to North America in the early 1900’s as a contaminant in alfalfa seed.