Leaves opposite, simple, ovate, 3.5 to 17 cm long, 2.5 to 11 cm wide, crenate to serrate. Easily confused with near relatives that are not poisonous.
Positive identification requires the services of a trained botanist.
The toxic principle has been identified as an alcohol called tremetol. It is found in all parts of the plant whether green or dry. All domestic livestock, some laboratory animals, and human beings are all susceptible to the effects of this plant. Animals may be poisoned from consuming the actual plant or from ingesting milk from cows, sheep or mares that have eaten the plant. Animals are stiff and sluggish, stand with feet wide apart and may eventually become recumbent.