Plants dull brown to red-brown, to 23 mm. Leaves erect-spreading to subsecund, narrowly lanceolate, gradually acuminate, acute, ± keeled above; margins plane, sinuate-dentate distal to the shoulders, serrulate at apex; costa subpercurrent or, in perichaetial leaves, shortly excurrent; distal cells long-rectangular, 5--10:1, usually slightly inflated in a marginal row. Seta to 7 mm, red-brown. Capsule 0.3--0.8 mm, erect and symmetric or nearly so, smooth (or rarely ± furrowed when old and empty); annulus none; operculum 0.3--0.5 mm, conic, short-rostrate; peristome teeth ca. 300 µm, divided 1/2 length distally. Spores 10--18 µm, nearly smooth.

Capsules mature spring and summer. Wet soil on banks of roads and streams; low to medium elevations; B.C., N.B., N.S., P.E.I., Que.; Alaska, Ala., Calif., Conn., Del., Ga., Idaho, Ill., Iowa, Ky., Mass., Md., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., Tenn., Vt., Va., W.Va., Wash.; Europe (England, Germany, Russia, Sweden); Asia (Japan).

The best means of identification of this species are provided by smooth, erect capsule and sinuate-dentate leaf margins with clear, somewhat inflated marginal cells. The distribution of the species for the United States reported above includes reports by H. A. Crum and L. E. Anderson (1981), R. K. Lampton (1970), B. D. Mahler and W. F. Mahler (1980), J. A. McCleary and P. L. Redfearn (1979), D. H. Norris and J. R. Shevock (2002), P. L. Redfearn (2001), J. A. Snider and B. K. Andreas (1996), J.. A. Snider et al. (1986), J. C. Wilkes (1965), I. A. Worley and Z. Iwatsuki (1970). Specimens from Costa Rica and Honduras are misnamed.