Leaves oblong-lanceolate to long-elliptical, apex acute, mucronate, margins recurved at base, bordered in proximal 2/3 to throughout with 3--5 rows of thicker-walled cells, 1--3:1; costa short-excurrent, lacking an adaxial pad of cells, distally very gradually narrowing, 3--5 cells across the weakly convex adaxial surface; distal laminal cells rounded-hexagonal, (10--)15--18 µm wide, 1:1, strongly papillose with 4--5 2-fid papillae. Sexual condition autoicous. Sporophytes exerted. Seta 1--3 cm. Capsules stegocarpic, not systylius, cylindric, erect and nearly straight, urn 4--6 mm; peristome 1700--2000 µm, teeth of 32 filaments twisted at least 1 full turn, basal membrane high, ca. 1000 µm; operculum ca. 1.5--2.5 mm. Spores (8--)12--18 µm, spheric, finely papillose.

Capsules mature spring--early summer. Soil; low; moderate elevations; Alta., B.C.; Calif., Colo., Ill., Mont., Oreg., Utah, Wash.; Europe; Asia; n Africa.

Forms of Tortula subulata may approach T. mucronifolia in the indistinct laminal border, though the laminal cells are quite papillose. The European T. subulata var. angustata (Schimper) Limpricht, characterized by narrower leaves, a more acute, denticulate apex, with a stronger border, is not recognized here because North American plants that approach this variant fully intergrade with the typical variety (see discussion by W. C. Steere 1939).