Parthenium hysterophorus is a species of flowering plant in the aster family, Asteraceae. It is native to the American tropics. Common names include Santa-Maria, Santa Maria feverfew, whitetop weed, and famine weed. In India, it is locally known as carrot grass, congress grass or Gajar Ghans. It is a common invasive species in India, Australia, and parts of Africa. The pollen grains of Parthenium hysterophorus invades disturbed land, including roadsides. It infests pastures and farmland, causing ...