Plants light green. Stems 2-3(-4) mm. Leaves obovate to ovate-lanceolate, distal leaves 2-3 mm; margins toothed or occasionally smooth distally; costa sub-percurrent to short-excurrent. Specialized asexual reproduction absent. Seta 0.5-1.2 mm. Capsule immersed, 1-1.2 mm, broadly cupulate; neck short, indistinct; exothecial cells irregular hexagonal or oblong, walls somewhat unevenly thickened; suboral cells consisting of 1-3 rows of short-rectangular cells. Spores 30-38 µm, papillose.
Capsules mature late fall-spring. Wet soil in disturbed places; moderate to high elevations; B.C., N.B., N.S., Ont., Que.; Colo., Iowa, Ky., La., Md., Minn., N.J., Oreg., Pa., Tex., Wash., Wis.; South America.
Physcomitrium immersum is easily recognizable by its immersed, broadly cupulate capsules that are usually clearly visible within the spreading leaves.