Plants highly variable in size and habit but usually rather tall and robust. Stems (2--)5--10(--70) cm. Leaves loosely imbricate to rather distant; sheath clasping the stem and usually plainly visible wet or dry; blade typically divergent and sharply toothed to the base; marginal cells of lamellae in section broader than those beneath, retuse to distinctly notched, with prominent knobs; perichaetial leaves not markedly longer than the foliage leaves, ending in a short, roughened spinulose tip. Capsule short-rectangular.

Moist organic soil in wet habitats, pastures, old fields, and meadows, peatlands, margins of bogs or swamps, often covering extensive areas, low to medium elevations, widespread in the boreal forest; rare north of the tree line and absent from the high Arctic (D. G. Long 1985); Greenland; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Ark., Calif., Colo., Conn., Del., Fla., Ga., Hawaii, Ida., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W. Va., Wis., Wyo.; n and c Europe; n and e Asia; n Africa; Atlantic Islands (Macaronesia); Pacific Islands (New Zealand); Australia.