1. Blade without a central axis, forked into two equal parts, each with an arching axis.
Adiantum
1. Blade with a single central axis.
2. Petioles green to straw-colored for at least the upper 1/3 to1/2, rachis green; leaves dimorphic, the fertile longer than the sterile and with narrower segments.
Cryptogramma
2. Petioles and rachis dark brown to almost black throughout; leaves essentially uniform.
Pellaea
All species found in Pteridaceae
Citation:
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. August 25, 2019. https://michiganflora.net/family.aspx?id=PTERIDACEAE.