Sphagnum trirameum Crum, Bryologist 92: 104. 1989.

Type: Sharp 5143.

Plants small, in soft, loose, yellow-green mats; cortical cells 1-layered, without pores; wood cylinder yellow. Stem leaves 1.4 mm long, oblong-triangular, bluntly obtuse, somewhat concave at the tip, bordered to the base by 3–4 rows of linear cells, entire; hyaline cells fibrillose on both surfaces throughout, often 1-divided, on the outer surface with membrane pleats and 1–6 small commissural and end pores and pseudopores, often in short rows of 2 or 3, on the inner surface with very few small end pores. Branches in fascicles of 3, all spreading, slenderly tapered; cortical retort cells differentiated. Branch leaves loosely spreading, 1.2–1.4 mm long, concave, ovate, bordered by 4–5 rows of linear cells, entire except at the narrow, truncate apex; hyaline cells moderately convex on both surfaces, on the outer surface with membrane pleats and few small end and commissural pores and pseudopores and often cross-connecting fibrils, on the inner surface with very few small pores at ends and corners; green cells in section very narrowly rectangular, equally exposed on both surfaces.