Sisymbrium altissimum is an annual/biennial herb native to Eurasia. Plants can reach almost 5 ft. (1.5 m) in height.
Foliage
Cauline (stem) leaves are alternate, 0.5-5 in. (1.3-12.7 cm) long and decrease in size up the stem.
Flowers
Flowering occurs in late spring to summer, when small, 4-petaled, yellow to white flowers develop in groups at the apex of the stems.
Fruit
Fruits are narrow seed pods that are 2-4 in. (5-10 cm) long and contain more than 120 seeds.
Ecological Threat
Sisymbrium altissimum was first seen in the United States in 1878 in Philadelphia; seeds were probably introduced accidentally in ship ballast. Plants invade fields, open forests, and other disturbed open areas.