This family comprises of two species of Penthorum, one in eastern Asia and the other in eastern and midwestern North America.
All species found in Penthoraceae
Citation:
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. June 19, 2018. https://michiganflora.net/family.aspx?id=Penthoraceae.