Authors: Richard E. Andrus

Plants moderate-sized to robust, somewhat lax in shade forms to quite compact and stiff in open grown forms; green to pinkish green to reddish purple; forms lawns in shaded habitats and low to moderately tall, dense hummocks in open habitats. Stems green to purplish red, superficial cortical cells with spiral reinforcing fibrils clearly visible, usually 1 or 2 pores per cell, comb-fibrils lacking on interior wall. Stem leaves to 2 ´ 0.7 mm; rarely hemiisophyllous; hyaline cells non-ornamented, mostly nonseptate. Branches long and tapering to short and pointed, leaves loosely imbricate. Branch fascicles with 2--3 spreading and 2--3 pendent branches. Branch stems with hyaline cells non-ornamented; no or weak funnel-like projections on the interior end walls, large round pores on superficial cell wall. Branch leaves broadly ovate, to 2 ´ 1 mm or more wide, broadly ovate, hyaline cells non-ornamented, convex surface with round to elliptic pores along the commissures,; chlorophyllous cells short-elliptic in transverse section and well-enclosed on both surfaces. Sexual condition dioicous. Capsules with numerous pseudostomata .Spores 22--30 µm; roughly papillose to nearly smooth, with distinct Y-mark sculpture on distal surface; proximal laesura 0.50--0.80 spore radius.

Capsules mature mid-summer. Very wide ecological amplitude, ombrotrophic to rich fen peatlands and in forested and open mires; Alta., B. C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Cal., Conn., Del., Fla., Ga., Idaho, Ill., Ind., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., N.H., N.J., N.Y., N.C., Ohio, Oreg., Pa., S.C., Tenn., Tex., Vt., Va., Wash., W.Va., Wis.; South America, Eurasia.

As the only boreal sect. Sphagnum species with a reddish purple color, S. magellanicum is usually easy to identify. The branch leaf chlorophyll is confusable only with S. alaskense , which is less enclosed on both surfaces, and S. centrale, which has thickened end walls on the chlorophyll cells that give them a narrow exposure on the concave surface.