Dryopteris filix-mas L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Rhizome ascending or erect; lvs mostly deciduous, appearing more delicate and finely divided than in spp. 5 and 6; petiole a third as long as the blade, its numerous scales pale, concolored, the broad, toothed ones intermingled with narrow, hair-like ones; blade to 10+ dm, mostly 1.5–3 dm wide; pinnate-pinnatifid with numerous (mostly 20–30 pairs) of pinnae to 15 × 4 cm, the largest pinnae near or a little below the middle and with (15)20+ pairs of segments, many of the segments evidently contracted at the base; larger ultimate segments (0.7–)1–1.5(–2) cm; ramentum ± plentiful on the rachis and costae, sometimes on the lower surface of the blade, chiefly of narrow, elongate, hair-like scales, that of the rachis sometimes partly of more evident (but still narrow) scales; 2n=164. Thickets, moist woods, and streambanks; circumboreal, extending s. to Vt., n. Mich., ne. Ill., S.D., and Mex.