Phegopteris excelsior (Thelypteridaceae): A New Species of North American Tetraploid Beech Fern Author Patel, Nikisha R. Pringle Herbarium, Department of Plant Biology, 111 Jeffords Hall, University of Vermont, 63 Carrigan Drive, Burlington, Vermont 05405, U. S. A. Author Fawcett, Susan Pringle Herbarium, Department of Plant Biology, 111 Jeffords Hall, University of Vermont, 63 Carrigan Drive, Burlington, Vermont 05405, U. S. A. Author Gilman, Arthur V. text Novon, A Journal for Botanical Nomenclature 2019 2019-11-04 27 4 211 218 http://dx.doi.org/10.3417/2019409 journal article 10.3417/2019409 3ec27add-200f-4d9f-9fd3-a46ed282720a 4561918 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