Rhizome 1 mm thick, the scales few, 3-4 mm; lvs numerous, 5-15 cm, the petiole to 4 cm, brownish at base, green distally; blade thin, not evergreen, linear-oblong, pinnate throughout, to 1.5 cm wide, acute, scarcely narrowed toward the base, the rachis green and flattened; pinnae 9-16 pairs, subopposite at base, alternate upwardly, sessile, 3-9 נ2-4 mm, obtuse, cuneate at base, bluntly toothed, not auriculate; 2n=72. Shaded limestone rocks; circumboreal, in Amer. s. to N.S., n. Vt., n. N.Y., Wis., Colo., and Wash.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.