Plants: small, in loose to dense tufts, yellowish or bright green, brown proximally. Stems: 1–6 cm, erect, simple or 2-fid, tomentose proximally. Leaves: erect-spreading when dry, somewhat divergent when moist, triangular- to slightly ovate-lanceolate, 1–2.3 mm; margins plane or sometimes narrowly revolute, serrulate nearly to base, teeth single; apex acuminate; costa percurrent to long-excurrent, abaxial surface weakly papillose; laminal cells rectangular, less than 9:1, prorulose, prorulae rounded, near distal ends or sometimes both ends on abaxial side; basal cells oblong, 18–45 × 6–15 µm; distal cells linear oblong, 20–30 × 4–8 µm. : Specialized asexual reproduction by propagula sometimes borne in leaf axils. Sexual: condition dioicous; perigonia discoid. Seta: 1.5–4 cm, flexuose. Capsule: 1–2.5 mm. Spores: spheric, 20–30 µm. Phenology: Capsules mature Mar–Sep.

Rock, soil, wet places, roadsides, springs. low to high elevations (30-3000 m). Alta., B.C., Man., N.S., Que., Ala., Ariz., Ark., Colo., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Mich., Minn., Miss., Mo., Nebr., N.H., N.Mex., N.Y., N.C., Ohio, Okla., Oreg., Pa., Tenn., Tex., Utah, Vt., Va., W.Va., Wis., Wyo., Mexico, Central America, n South America (Colombia), Europe, Asia, n Africa, Atlantic Islands (Macaronesia).

Philonotis marchica is recognized by its usually plane, singly serrulate leaf margins and laminal cells bearing rounded prorulae near the distal ends. Philonotis capillaris, a species mainly of Pacific coastal habitats, shares with P. marchica the singly serrulate leaf margin. However, P. capillaris, in contrast to P. marchica, has a more or less decumbent, flaccid habit, more distant, widespread leaves, shorter and broader distal laminal cells and obscure prorulae in the basal half of the leaf.