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
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 15, 2017. http://michiganflora.net/family.aspx?id=PENTHORACEAE.