Parthenium hysterophorus is a species of flowering plant in the aster family, Asteraceae, that is native to the American tropics.[1] Common names include Santa Maria Feverfew and Whitetop Weed.[2] It is a common invasive species[3] in India,[4] Australia, and parts of Africa. P. hysterophorus invades all disturbed land, including farms [5][6][7][8][9] pastures, and roadsides. In some areas, outbreaks have been of almost epidemic proportions, affecting crop production, livestock and human health.[10][11] In India, it is locally known as Congress Grass or Gajar Ghans.[12] It was first present as a contaminant in imported wheat.[13] It can trigger allergies and is a common cause of pollen allergy.[14]