Gymnostomum ovatum Hedwig, Sp. Musc. Frond., 31, plate 2, figs. 1-3. 1801

Leaves with distal lamina smooth or rarely papilose; awn smooth or rarely with a few teeth; lamellae 8-16 cells in height, not lobed, seldom bearing filaments. Capsule stegocarpous, emergent to exerted, ovoid, annulus present, operculum cells in straight rows; eperistomate. Calyptra cucullate or rarely mitrate.

Spores mature spring. Soil (volcanic, dry saline), frost boil, low desert scrub areas; moderate elevations (900-1600 m); Alta., B.C., Man., N.W.T., Nunavut, Ont., Que., Sask., Yukon; Alaska, Ariz., Calif., Colo., Idaho, Kans., Mont., Nebr., Nev., N.Mex., N.Dak., Oreg., S.Dak., Tex., Utah, Wash., Wyo.; s South America; Europe; Asia; n Africa; Australia.

Pterygoneurum ovatum is the most common species of the genus and serves to stabilize arid soils (S. Flowers 1973). The setae may reach 3 mm. Faint thickenings reminiscent of a rudimentary peristome can sometimes be found associated with spore sac remnants dug out of the operculum, and the laminal distal cells may by simply papillose abaxially as in P. lamellatum. R. T. Wareham (1939) found the characters of Pterygoneurum ovatum var. incanum Juratzka, the long awns and short setae, inconstant in both American and European material.