Thelypteris phegopteris (L.) Sloss.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Lvs scattered on long, slender, densely hairy and scaly rhizomes, to 5 dm, the pilose and scaly petiole mostly longer than the blade; blade 10–25 cm, mostly 1–2 times as long as wide, ciliate-margined, pinnate-pinnatifid, pinnae mostly 10–15 opposite or offset pairs below the pinnatifid apex, to 3 cm wide, approximate, broadly sessile and narrowly confluent along the rachis, only the lowest pair a little removed and often retrorsely divergent, commonly a little shorter than the second pair; segments of the pinnae oblong, obtuse, entire or the largest crenate to subpinnatifid; veins simple or once forked; rachis, costae and veins hairy beneath, the rachis also with abundant brown, lance-ovate scales; indusium none; 2n=90. Moist cliffs and woods; circumboreal, s. in Amer. to N.C., Tenn., Io., and Oreg. (Dryopteris p.; Phegopteris polypodioides)
narrow beech-fern, northern beech-fern