Parthenium L.
Parthenium is a New World genus of ca. 16 species. Most are confined to the warm-temperate and tropical regions, some extending northwards to the United States. One species, Parthenium hysterophorus, is a notorious agricultural weed and has been recorded in Belgium as well.
Literature:
Brunel S., Panetta D., Fried G., Kriticos D., Prasad R., Lansink A.O., Shabbir A. & Yaacoby T. (2014) Preventing a new invasive alien plant from entering and spreading in the Euro-Mediterranean region: the case study of Parthenium hysterophorus. Bulletin OEPP/EPPO Bulletin 44(3): 479-489.
Mears J.A. (1975) The taxonomy of Parthenium section Partheniastrum DC. (Asteraceae – Ambrosiinae). Phytologia 31: 463-482. [available online at: http://biostor.org/cache/pdf/a0/9a/e1/a09ae1d5afe3b4deca3142fc1572513c.pdf]
Rollins R.C. (1950) The guayule rubber plant and its relatives. Contr. Gray Herb. 172: 1-73.
Strother J.L. (2006) Parthenium. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 21. Oxford University Press, New York-Oxford: 20-22. [available online at: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=124104]