Rhizome 1.5-2 mm thick, the lanceolate brown scales 1.5-2 mm; lvs numerous, 5-25 cm, the purple-brown petiole to 6 cm; blades uniform, linear, pinnate throughout, to 19 נ1.7 cm, acute to attenuate above, usually not narrowed below, thin, dark green, the thin, flexible rachis almost wholly dark; pinnae 9-20 pairs, mostly opposite, oval to round oblong, oblique with the upper side the larger, but not auriculate, 4-8 נ3-6 mm, mostly crenate, subsessile; 2n=72, 144. On shaded, mostly calcareous rocks; interruptedly circumboreal, and nearly throughout our range, s. to Ga. and Tex.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.