Plants: moderate-sized to often quite robust, ± weak-stemmed, lax; green, bluish green, green and brown to dark golden brown, often speckled in appearance; found submerged in shallow water, stranded along shore lines in loose carpets. Stems: brown, superficial cortical layer with spiral reinforcing fibrils clearly visible, usually many pores per cell (1–6), comb-fibrils on interior wall. Stem: leaves 1.1 × 1 mm; rarely hemiisophyllous; hyaline cells non-ornamented, frequently septate. Branches: clavate and rounded at distal end. Branch: fascicles with 2 spreading and 2 pendent branches. Branch: stems with hyaline cell comb-lamellae visible on interior cortex wall, cortical cell end walls with conspicuous funnel projections more than 1/2 length of cell, superficial cortical wall aporose. Branch: leaves broadly ovate, 2.4 × 1.7 mm; hyaline cells on convex surface with numerous round pores along the commissures, comb-lamellae on hyaline cell walls where overlying chlorophyllous cells; chlorophyllous cells broadly triangular in transverse section and well-enclosed on the convex surface. Sexual: condition dioicous. Capsule: with pseudostomata. Spores: 22–29 µm; finely papillose on both surfaces; indistinct triradiate ridge on distal surface; proximal laesura 0.5–0.6 spore radius.
Stream channels, shallow ponds, coniferous and hardwood swamps and pocosins. low to moderate elevations. Ala., Fla., La., N.J., N.Y., N.C., S.C., Tex., Mexico, West Indies, South America.
Sphagnum portoricense is normally very easily distinguished because of its wet growing habit and strongly clavate branches.