2a. var. glabella

Spores 60–72 mm in diameter, 32 per sporangium. 2n=116 (apomictic). 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.

This is the common, 32-spored, apomictic variety of the species. Where it occurs with var. missouriensis, hybrids between the two varieties can be found. These are fertile, pentaploid (2n=145) apomicts. They are morphologically indistinguishable from var. glabella, even by spore size, and were first identified using genetic markers (allozymes) (Gastony, 1988).