Three images of Senecio jacobaea, Tansy Ragwort; Compositae or Asteraceae, Aster Family is a European medicinal plants, toxic plants and invasive weed, found in much of the United States. Leaves a folk medicine in Europe gargle for mouth sores. Externally leaf juice used as a treatment for sores and ulcers. Also poulticed for bee stings. Plant is toxic to livestock and contains liver-toxic alkaloids.