Polytrichum septentrionale Bridel, J. Bot. (Schrader) 1800(1): 285. 1801; Pogonatum alpinum var. septentrionale (Bridel) Bridel; Polytrichum alpinum var. septentrionale (Bridel) Lindberg; P. norwegicum Hedwig

Stems to 2 cm, slender and wiry, in dense tufts. Leaves densely imbricate, not fragile, channeled and incurved when dry, scarcely spreading when moist; not constricted at junction of sheath and blade, the blade persistent, sheath broadly elliptic; marginal lamina typically entire, or finely and remotely serrate toward the tip. Capsule small and subglobose.

Soil; moderate to high elevations; Alta., Man., Nfld. and Labr. (Labr.), N.W.T., N.S., Nunavut, Que.; Calif., Colo., Mont., Utah, Wash., Wyo.; Europe; n Asia.

Variety septentrionale is an arctic-alpine taxon. In arctic North America there is a correlation between capsule shape and leaf serration, plants with distinctly serrate leaves having ovoid-cylindric or cylindric capsules, whilst those with entire or subentire margins have subglobose or ovoid capsules (D. G. Long 1985).