Horses are most severely affected, while other grazing animals are moderately susceptible. The plant's foliage has a distinct, foul odor. This summer annual can grow to heights of approximately 5 feet. The tubular flowers are very showy and range in color from white to purple. Seedpods are egg-shaped and covered with prickles.
Leaves contain lower concentrations of the alkaloids.
There is no reported safe quantity of hay that can be fed to livestock. Because the alkaloids act on the nervous system, bodily functions are affected. Animals may have dilated pupils, become agitated, have increased heart rate, tremble, become delirious, appear to be hallucinating, have convulsions, become comatose, and possibly die. The plant grows in dense stands, reaches heights up to 8 feet in some situations and often has reddish brown blotches on its leaves. The seed heads are large, open and loose.