Toxic signs are more apparent in animals that cannot vomit, such as horses. They tend to produce a basal rosette of leaves, and later produce alternate leaves along their stems. Most mustards have yellow flowers with four petals. Some of the common species in Missouri are wild mustard, field pennycress, tansy mustard, yellow rocket and Virginia pepperweed. Generally, for problems to occur, large quantities have to be consumed over a period of time.
Flowers are yellow and occur in clusters at the ends of branches.
The fruit is prickly, glossy and leathery brown and has a pale scar. Gastrointestinal signs occur first, with salivation, vomiting, abdominal pain and diarrhea. If enough of the toxin was ingested, neurological signs may develop, including trembling, staggering and difficult breathing. The leaves are pinnately compound, highly divided with very small leaflets giving the plant a fernlike appearance. Leaves are alternate, egg-shaped, smooth and glossy in appearance.