Roots not proliferous. Stems erect, unbranched; scales brown, lanceolate, 3--6 × 1--1.5 mm, margins entire. Leaves monomorphic. Petiole brown to straw-colored, dull, 3--10 cm, 1/8--1/4 length of blade; indument of brown, narrowly lanceolate scales. Blade linear, simple, 8--35 × 2--4.5 cm, thick, papery, nearly glabrous; base cordate; margins entire; apex acuminate, not rooting. Rachis brown proximally, straw-colored distally, dull, glabrous. Veins free, obscure. Sori numerous, perpendicular to rachis, or nearly so, usually restricted to distal 1/2 of blade. Spores 64 per sporangium. Usually 2 n = 144.
Roots coarse, fibrous, not proliferous; rhizomes erect; rhizome scales blackish to dark brown, clathrate, 1.5–6 x 1–1.5 mm, entire or weakly short-ciliate; fronds clumped, 9–65 cm long; stipes brownish to stramineous, dull, 1.5–20 cm x 1.5–5 mm, ca. 1⁄5– 1⁄3 of frond length, with dense, linear to lanceolate, tan, ultimately clathrate scales, not alate; blades thick-herbaceous to subcoriaceous, simple, 7–22(–35) x 1.8–5 cm, oblong, entire to slightly undulate, bases cordate to subcordate or with two downward-directed lobes, apices acute, proliferous buds absent; rachises brownish at bases, light green to stramineous distally (lighter than the blades), dull, with sparse to dense scales 1–2.5 x 0.1–0.2 mm, not winged; pinnae absent; veins simple or 1- or 2-forked, obscure, parallel for most of their length, tips evident adaxially; indument abaxially of scattered, linear scales to 0.5–1 x 0.1 mm, also with sparse catenate hairs to 0.5 mm long; sori paired, facing each other on adjacent veins, usually confined to distal 1⁄2–2⁄3 of blades; indusia (2–)6–15 x 0.3–0.7 mm, margins entire or repand; spores reniform; 2n=144 (Can, USA, Chis, see Viane & Reichstein, 1991: 163).
Epipetric on moist calcareous rocks (dolomitic limestone) in sinkholes, at cave entrances, and on cool, moist talus, and on limestone cliffs, occasionally epiphytic on old oaks, in deep shade; 2100–2200 m. Can (Ont), USA (spotty in Ala, Mich, NY, Tenn); Mexico; Hisp (Haiti).