KEY TO NORTH AMERICAN PHEGOPTERIS 1. Blades of fronds elongate, widest toward the middle......................... P. decursive-pinnata (H. C. Hall) Fée 1 '. Blades of fronds widest at the base. 2. Blades of fronds usually slightly wider than long; all pinnae, including proximal pair, winged to rachis; proximal pinnae (2–)3X as long as wide............................................. P. hexagonoptera (Michx.) Fée 2 '. Blades of fronds longer than wide; pinnae winged to rachis except proximal pair not winged to rachis (rarely, more than one proximal pinna pair not winged in P. connectilis); proximal pinnae 4–5X as long as wide. 3. Blade outline ovate, proximal pinnae strongly declined and adaxially inflexed, average 4X as long as wide; spore length averaging 55 ± 5.4 μ m...................................... P. connectilis (Michx.) Watt 3'. Blade outline triangular, proximal pinnae slightly to moderately declined and adaxially inflexed, average 5X as long as wide; spore length averaging 64 ± 4.6 μ m......... P. excelsior N. R. Patel & A. V. Gilman

Published as part of Patel, Nikisha R., Fawcett, Susan & Gilman, Arthur V., 2019, Phegopteris excelsior (Thelypteridaceae): A New Species of North American Tetraploid Beech Fern, pp. 211-218 in Novon, A Journal for Botanical Nomenclature 27 (4) on page 217, DOI: 10.3417/2019409, http://zenodo.org/record/4561918