Roots to 25 per plant, tan to brown, 0.5-1.5mm diam., straight, producing proliferations. Stem upright, to 1.5 cm, 4 mm diam., leaves 1-2 per stem. Trophophore stalk to 0.1 cm, 0.01 times length of blade. Trophophore blade erect to spreading, commonly ± folded when alive, uniformly pale green throughout when dried, dull, ovate to ovate-lanceolate, 10 × 4.5 cm, firm, herbaceous, base narrowed abruptly, apex with apiculum to 0.8 mm; venation complex-reticulate, veinlets forming numerous, very tiny, secondary areoles within the major areoles. Sporophores arising at ground level, 1.3-2.5 times as long as trophophore; sporangial clusters 2-4 × 0.13-0.31 cm, pairs of sporangia 20-40, apiculum 0-1.3 mm. Leaves appearing early-late spring, often with second flush later in season following summer rains. Mostly in soil over limestone in open fields, pastures, and cedar glades; 50-1000 m; Ala., Ariz., Ark., Fla., Ga., Ill., Ind., Kans., Ky., La., Miss., Mo., Ohio, Okla., N.Mex., N.C., Tenn., Tex., Va., W.Va.; Mexico; Central America.
Bases of old lvs persisting on the rhizomes; lvs often 2 or more, the blade usually somewhat trough-shaped in life, acute at each end, apiculate, the veins forming areoles that enclose many smaller areoles and also some free veinlets; otherwise much like O. vulgatum. Woods, pastures, and ledges, mostly in calcareous soils; nw. Va. to s. Ill. and e. Kans., s. to Fla., Ariz., and Mex. Spr.-early summer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
There is a fragmentary specimen in the herbarium of the New York Botanical Garden which R. T. Clausen has seen and reported in the Mem. Torrey Club 19: no. 2:140. 1938 as belonging to this species. Clausen in a letter to me dated June 1, 1938, confirms his examination of the specimen and determination. The specimen was collected by L. M. Underwood in June, 1893, on the campus of Indiana University.