Leaves with distal lamina smooth; awn smooth or sharply serrulate; lamellae 10-12 cells in height, not lobed, sometimes bearing fila-ments. Capsule stegocarpous (or stegocarpous but bursting irregu-larly), immersed to emergent, short-ovoid, annulus present, operculum cells in straight rows; eperistomate. Calyptra mitrate.

Varieties 2 (2 in the flora): North Temperate Zone, s South America.

Pterygoneurum subsessile is an abundant moss in the arid West, often occurring with P. ovatum. In some specimens, the perigoniate plants appear separate, but this species and doubtless others are apparently occasionally rhizautoicous. Following the reasoning of R. T. Wareham (1939), var. henrici is placed with the typical variety. The characters associated with P. californicum (H. A. Crum 1967) are poor: the spores are finely papillose, the leaf cells do have weak collenchymatous thickenings, and the calyptra is long-mitrate.

Capsule stegocarpous, spores released after operculum falls.

Spores mature late winter-spring. Soil (sandy, volcanic), alkali flats; moderate to high elevations (600-1700 m); Alta., B.C., Sask., Yukon; Alaska, Ariz., Calif., Colo., Idaho, Ill., Iowa, Kans., Minn., Nebr., Nev., N.Mex., N.Dak., Okla., Oreg., S.Dak., Tex., Utah, Wyo.; s South America; Europe; Asia; n Africa.