1. Leaves gradually tapered to the base, elliptic in outline (widest ± at the middle).
1. Leaves abruptly tapered to the base, ovate in outline (clearly widest below the middle).
All species found in Ophioglossum
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. February 23, 2018. http://www.michiganflora.net/genus.aspx?id=Ophioglossum.