Gymnostomum pennatum Hedwig, Sp. Musc. Frond., 31. 1801; Schistostega osmundacea D. Mohr

Leaves of sterile shoots 0.5-1.2 mm, ecostate, median cells smooth, oblong-rhomboidal, thin-walled, 16-20 µm wide, decurrent, confluent at the base, margin entire, weakly bordered by narrow, elongated cells. Protonemal gemmae sticky, obclavate, 80-200 × 15-20 µm, 3-4 cells in length, tapering and thickened near apex. Seta 2-5 mm. Capsule erect, light brown, smooth, subglobose or ovoid, annulus absent. Spores yellowish green, pitted-reticulate, 10-13 µm.

Capsules mature late spring-early summer. Usually found on mineral soil in crevices on lower, sheltered parts of upturned tree root wads, ceilings of caves, crevices in soil banks, animal burrows, rarely on the shaded sides of deep pits along the upper banks of perennial streams, occasionally on rock; low to high elevations (0-1700 m); Alta., B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., Que.; Alaska, Idaho, Maine, Mich., Minn., Mont., N.H., N.Y., Ohio, Oreg., R.I., Vt., Wash., Wis.; Eurasia.