Athyrium pycnocarpon (Spreng.) Tidestr.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Rhizome ± creeping; lvs scattered, 6–11 dm, the blade longer than the petiole, 11–20 cm wide, gradually tapering above, only slightly reduced below, glabrous except for a few septate brown hairs on the rachis, costae, and veins; pinnae 20–30 pairs, subdimorphic, the fertile one slightly narrower than the sterile; sterile pinnae narrowly lance- linear, 7–12 cm × 10–13 mm, subsessile and rounded or subtruncate at the base, gradually tapering to the base, subentire or slightly toothed, the veins simple or forked, tending to run to the sinuses; indusia glabrous, narrow, elongate, straight or nearly so, following the anterior vein-branch and often reaching from near the costa to near the margin; 2n=80. Cool woods and talus slopes in circumneutral soil; s. Que. to Ont. and Minn., s. to Fla. and La. (Asplenium p.; Diplazium p.; Homalosorus p.)