Dicranum saxicola F. Weber & D. Mohr, Neues Bot. Taschenb. Anfänger Wiss. Apothekerkunst 18: 167, 466. 1807

Plants glossy. Leaves 2-3 mm, often circinately curled when dry, margins entire, erect; apices acute, subcucullate. Seta 5-7 mm, twisted below the capsule and often flexuous when dry, often recurved when wet. Capsule 1-1.2 mm, smooth or slightly wrinkled when dry; operculum red proximally, 0.5-0.7 mm; peristome teeth red. Calyptra 0.7 mm, mostly shallowly lobed proximally. Spores 8-10 µm.

Capsules mature Oct.-May. Forests or openings on acidic sandstone boulders and cliffs, and sandstone rock shelters; moderate elevations (400-1300 m); P.E.I., Que.; Ala., Ark., D.C., Ind., Ky., Mass., N.H., N.J., N.Y., N.C., Ohio, S.C., Tenn., Va., Wash.; Europe.

Campylostelium saxicola is a tiny moss with glossy, crisped, or sometimes circinate leaves; it grows on shaded boulders in forests over most of its range but in rock shelters in the southern portion. Campylostelium saxicola is wide-spread in the flora area but infrequently collected due to its inconspicuous nature. Its small delicate stature, smooth calyptra, and usually flexuous-curved seta distinguish it from Ptychomitrium.