Parthenium hysterophorus

Family: Asteraceae
Common Names: Santa Maria Feverfew,  Ragweed Parthenium, Whitetop Weed 

Introduced to USA: AL, AR, CT, DC, FL, HI, IL, KS, LA, MA, MD, MI, MO, MS, NJ, NY, OH, OK, PA, SC, TX, VA + PR, VI 

Additional Resources:
Flora of North America