Gymnocarpium dryopteris (L.) Newman
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Petiole 10–30 cm; blade yellow-green, scaleless, deltoid-pentagonal, to 18 × 25 cm, bipinnate-pinnatifid to tripinnate-pinnatifid, glabrous or occasionally slightly glandular especially along the rachis, pinnae several pairs, opposite, the members of the lowest pair deltoid and each nearly as long as the rest of the blade, with a petiolule to 2.5 cm long, distinctly asymmetrical, the lowest basiscopic segment evidently the largest, mostly a third as long as the main rachis or longer; ultimate segments oblong, 8–18 mm, obtuse, the margins crenate to subpinnatifid, not recurved; veins 2–6 pairs, mostly simple; 2n=160 (ours). Cool woods and talus-slopes; circumboreal, s. to Va., N.C., O., Ill., Io., and Ariz. A vegetatively reproducing hybrid with the next is G. ×heterosporum W. H. Wagner.