Plants moderate to large-sized, dense and compact, pale green, brownish white, golden brown to variegated golden-brown, can be reddish in rocky seep habitats; forms small, tufted compact cushions. Stems brown. Stem leaves small, 0.3--0.7 mm, triangular-lingulate with broad rounded apex, Branches short, crowded, and unranked. Branch fascicles 4--6 branches per fascicle, 2--3 spreading and 2--3 pendent, but plants frequently unbranched in young clones. layer of cortical cells, Branch leaves large, 1.4--3 mm, semi-squarrose to squarrose, ovate and abruptly involute in distal portion, appearing cucullate with toothed apex, usually no more than 6 teeth; hyaline cells with 5 or more ringed, round to elliptical pores on convex surface, numerous pseudopores on concave surface with 3 ringed corner pores occurring in 3's at adjacent cell angles; chlorophyllous cells elliptic in transverse section, entirely included by hyaline cells, slightly nearer to convex surface. Sexual condition monoicous. Capsules with abundant pseudostomata. Spores 25--35 µm; finely papillose on proximal surface, coarsely papillose on distal surface with raised Y-mark sculpture; proximal laesura short, 0.3--0.50 spore radius.

Capsules fairly common, mature summer. Ombrotrophic to weakly minerotrophic, commonly growing on poorly drained sand, siliceous rocks, bare peat; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Ark., Cal., Conn., Fl., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., N.H., N.J., N.Y., N.C., Ohio, Oreg., Pa., S.C., Tenn., Vt., Va., Wash., W.Va., Wis.; South America; Eurasia; Pacific Islands (New Zealand).

Sphagnum compactum is usually easily recognized by its combination of golden brown color and involute, cucullate branch leaves. Sphagnum strictum is paler and usually strongly squarrose.