Sphagnum portoricense Hampe, Linnaea 25: 359. 1852.

Plants robust, dark, greasy green above and brown below or yellow-brown throughout, in wide carpets; cortical cells in 3–4 layers, the outermost fibrillose, with 1–6 irregularly rounded pores; wood cylinder brown. Stem leaves lingulate, broadly rounded at the apex, with a broad, finely fringed mesh at the margins; hyaline cells often 1–2-divided, on the outer surface almost completely resorbed, on the inner surface with small pores and traces of fibrils, especially near the leaf apex. Branches in fascicles of 4–5 (2 spreading), stoutly club-shaped; cortical cells nested together by funnel-shaped bases porose at the bottom, fibrillose, the inner wall densely cross-fibrillose, the outer surface lacking pores. Branch leaves imbricate, dimorphous: those at the base of branches cucullate-concave, broadly ovate, hyaline-fringed, the hyaline cells on the outer surface strongly convex, almost entirely resorbed toward the leaf tip, with 7–10 large, elliptic commissural pores below, on the inner surface with about 4 small, elliptic corner pores in the upper part of the leaf but more numerous larger, round pores in side regions; leaves of the upper part of branches much larger, denticulate along a marginal resorption furrow, with hyaline cells resorbed on the outer surface only in a few apical cells; green cells in section equilateral-triangular and exposed on the inner surface (or rarely more or less trapezoidal with narrow exposure on the outer surface), the walls of adjacent hyaline cells usually beset with fringe fibrils (sometimes evident only near leaf bases).