Parthenium hysterophorus L. is one of the ten worst weeds in the world. Parthenium is a herbaceous annual or ephemeral member of the Asteraceae, reaching a height of 2 m. in good soil and flowering within 4-6 weeks of germination.
Large plants can produce more than 25000 seeds, distributed by floating on water or in the mud adhering to animals,vehicles and machinery.Parthenium is popularly known as Congress weeds, White top, Star weed, Carrot weed, Gajar ghas, Ramphool, Feverfew etc. Adverse effects of Parthenium on humans as well as on animals have been well documented. It is known to cause asthma, bronchitis, dermatitis and hay-fever in man and livestock.
Parthenium is a curse for the bio-diversity .Chemical analysis has indicated that all the plant parts including trichomes and pollen contain toxins called sesquiterpene lactones. The major component of these toxins being parthenin and other phenolic acids such as caffeic acid, vanillic acid, anisic acid, chlorogenic acid, parahydroxy benzoic acid and p-anisic acid are lethal to humans and animals. Parthenium was accidentally introduced in India in around 1956 and has since spread over most part of the country. Parthenium now occurs throughout the tropical and subtropical America from southern United States of America to southern Brazil and to Northern Argentina.%