Plants dark green, rufous-tomentose proximally, in dense tufts or intermixed with other bryophytes. Stems 1--3 cm, erect, simple or sparingly branched. Leaves laxly erect-appressed when dry, often somewhat incurved, erect-spreading when moist, ovate-lanceolate, sometimes acuminate, 0.8--1.2 mm; margins narrowly revolute near base, plane distally, serrulate throughout; costa subpercurrent to excurrent, smooth abaxially; laminal cells firm-walled, with a single centric papilla on both sides (papillae more prominent on adaxial side); distal cells rectangular, 15--26 × 6--8 µm; median cells short-rectangular, 15--20 × 8--10 µm; basal cells similar to median cells but subquadrate to quadrate. Specialized asexual reproduction by slender brood branches in leaf axils. Sexual condition dioicous. [Perigonia discoid. Seta 2.5--4 mm. Capsule spherical, 2--3 mm. Spores 19-24 µm].

Rocky cliffs or steep slopes, wet or dry sites; 0--2700 m; B.C., Nfld., Ont.; se Alaska, Calif., Mont., Wash., Vt.; Asia (Japan; Korea).

The dark green color and centrally papillose leaf cells make Philonotis yezoana one of the easiest to recognize of the flora species. Characters of sporophyte-bearing plants (Japan) are from W.M. Zales (1973).