(commonly known as cocklebur). Several species. The Common Cocklebur (X. strumarium), a native of North America, can be poisonous to livestock, including horses, cattle, and sheep. Some domestic animals will avoid consuming the plant if other forage is present, but less discriminating animals, such as pigs, will consume the plants and then sicken and die. The seedlings and seeds are the most toxic parts of the plants. Symptoms usually occur within a few hours, producing unsteadiness and weakness, depression, nausea and vomiting, twisting of the neck muscles, rapid and weak pulse, difficulty breathing, and eventually death. Xanthium has also been used for its medicinal properties and for making yellow dye, as indicated by its name (Greek xanthos = 'yellow')