Mnium marchicum Hedwig, Sp. Musc. Frond., 196. 1801; Philonotis muehlenbergii (Schwagrichen) Bridel

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 , prorulose, ; 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.

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.