Introduced from Europe and now found throughout the United States. It grows commonly in grain fields and pastures, and the strong odor of the plant causes a bitter flavored milk from livestock that eat it.
A winter or summer annual, beginning as a rosette of basal leaves and then producing the tall, branched stems that produce the flowers. Propagation is from seeds that may germinate at nearly any time of the year, from early spring to late fall.
Mature plants may be 18 inches tall, with profuse production of flowers and seeds. The basal leaves are lanceolate and with slightly wavy margins, but these leaves wither as the plant matures and produces stems. Leaves are alternate along the stem, and attach tightly to the stem with a clasping base. Both stems and foliage produce the unpleasant odor when they are damaged.
Flowers are produced from early spring into early summer as dense clusters of small, white flowers at the ends of the stems. These clusters are called racemes, and they elongate as the plant ages, continuing to produce new flowers at the top while the seed pods develop below, along the stem. Seed pods are very distinctive, being very flat, egg-shaped, and with a notch at the outer end.
Characteristicts Important to Control:
Plants grow best in moist, rich soils, but tolerate dry roadside conditions as well. Heavy and continual seed production allows infestations to spread quickly.