1. Leaves deeply pinnatifid or bipinnatifid; plants annual; pappus of 2 scales.
P. hysterophorus
1. Leaves merely toothed or crenate; plants perennial; pappus of 2–3 weak awns.
P. integrifolium
All species found in Parthenium
Citation:
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 14, 2018. https://michiganflora.net/genus.aspx?id=Parthenium.