2. Pellaea glabella Mett. ex Kuhn (smooth cliff brake) Pl. 14a,b,c; Map 64

Rhizome scales reddish brown, linear. Leaves clustered, 7–25 cm long. Petioles and rachises dark reddish brown to black, densely hairy with short, curly hairs on the upper surface. Leaf blades 1–2 times compound, linear lanceolate to narrowly oblong in outline, monomorphic. Leaflets 5–27 mm long, sometimes leathery, sometimes with 1–2 lobes at the base, narrowly lanceolate to ovate or oblong, glabrous. Sori in a continuous, marginal band around the pinnules, the edge of the recurved pinnule margins somewhat differentiated. Sporangia with 32 or 64 spores. Spores tan. 2n= 58 (sexual), 116 (apogamous). April–October.

Scattered throughout the Ozark and Ozark Border Divisions, locally north to Andrew, Knox, and Lewis Counties (northeastern U.S. and adjacent Canada, southwest to Kansas and Texas). Crevices and ledges of limestone and dolomite bluffs, boulders, and rock outcrops, rarely on sandstone.

Two varieties of P. glabella are found in Missouri, which cannot be differentiated reliably in the field, as the spores must be examined under a microscope.