Parthenium: a wide angle view.

Parthenium hysterophorus L. (congress grass, congress weed, carrot weed, wild feverfew, the “Scourge of India”) is an exotic weed that was accidentally introduced in India in 1956 through imported food grains.[1] It has become a common weed causing dermatitis of epidemic proportions.[2] The epithet “congress weed” refers to the US congress (who allocated the shipment for Pune, India).[3] In Pune, it found an ecological niche without natural enemies and spread rapidly along the canal banks, roads and railway tracks to become a major field weed.[4] Both rural and urban areas have been invaded by this weed. It is the leading cause of plant induced air-borne contact dermatitis in India[5] and has achieved major weed status in India and Australia within the past few decades.[6] The weed can affect human health, animal husbandry, crop production and biodiversity.[6]