1. Petioles and peduncles glabrous; leaves essentially glabrous beneath.
I. macrophyllum
1. Petioles and peduncles densely hairy; leaves densely hairy beneath.
I. tomentosum
All species found in Isotrema
Citation:
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 11, 2019. https://michiganflora.net/genus.aspx?id=Isotrema.