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).
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.