PARTHENIUM : The Congress Grass

Parthenium is a weed which is botanically known as Parthenium hysterophorous. It
is native to Tropical America. It was accidently introduced in India in the year
1956. Parthenium is an annual herb which is locally known as Congress Grass or
the Gajjar grass.

Plants of Parthenium have deep tap root system and multibranched erect shoot
system. Stems become woody on maturity.

http://mpmishra.blogspot.com/2009/07/parthenium-congress-grass.html