The leaves have smooth edges and no hair on them. Dyers woad produces abundant bright yellow flowers growing densely above the leaves. They have 4 petals that grow in groups at the end of numerous stems. Each flower produces one seedpod of about inches in length, which are formed as the flowers fade. The pods start out green but turn to a shiny black or deep purple color as the age.
Several pods grow on each stem and each pod contains one seed.
Dyers woad begins growth in the fall as a small rosette of leaves. These rosette leaves have fine hairs growing and are widest near the tip. The stems grow from the middle of the rosette leaves and can grow up to 4 inches per day when conditions are right. It generally doesn't flower until the second year of its life. Flowering in spring or early summer, the bright yellow flowers are obvious and attractive to many observers.