Brachythecium petrophilum R. S. Williams

Plants green, sometimes yellowish or brownish. Stems creeping, regularly pinnate, branches subcomplanate-foliate. Stem leaves erect-spreading, densely to loosely arranged, straight to slightly curved, ovate-lanceolate to lanceolate, 1-1.6 × (0.1-)0.2-0.5(-0.6) mm; margins serrulate to base, serrate to serrulate distally; laminal cells 45-90(-125) × 5-7 µm. Branch leaves ± falcate or occasionally straight. Seta rough throughout.

Mineral soil, humus, litter, decaying wood, trunk bases; low to high elevations (0-2100 m); Alta., B.C., Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Yukon; Calif., Colo., Conn., Del., Idaho, Maine, Mass., Mich., Minn., Mont., N.H., N.J., N.Y., N.C., Oreg., Pa., R.I., S.Dak., Utah, Vt., Va., Wash., W.Va., Wis.; Eurasia; n Africa; Atlantic Islands.

Variety velutinum is distinguished from most species in Brachytheciaceae by a small stature, narrow, more or less falcate leaves that usually spread from their bases, and somewhat complanate foliage.