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Rhizome 1–2 mm thick, the few linear-subulate dark brown scales 2.5–3.5 mm; lvs numerous, erect, uniform, 5–30 cm, the petiole to 7.5 cm, dark brown or purplish-black; blade linear-oblong, to 25 × 2.5 cm, pinnate throughout, acute above, narrowed below, thin, the straight, rather thick rachis almost wholly dark, with a few septate hairs but not scales; pinnae 14–30 pairs, mostly opposite, slightly deflexed, mostly 8–12 × 3–4 mm, mostly oblong, auriculate at the upper (and sometimes also the lower) base, rounded, slightly or scarcely crenulate, subsessile; spores 32 per sporangium; 2n=108, an apogamous triploid. Crevices of calcareous rocks, or in circumneutral soil; s. Pa. to Ill., Mo., and Kans., s. to trop. Amer.
