Sphagnum may have a number of different "Sphagnum" species. Individual peat moss plants consist of a main stem, with tightly arranged clusters of branch fascicles usually consisting of two or three spreading branches and two to four hanging branches. The top of the plant, or capitulum, has compact clusters of young branches. Along the stem are scattered leaves of various shapes, named stem leaves; the shape varies according to species. The leaves consist of two kinds of cells; small, green, living cells (chlorophyllose cells), and large, clear, structural, dead cells (hyaline cells). The latter have the large water-holding capacity. "Sphagnum", like
Aulacomnium palustre plant communities, and individual moss species often have low cover and/or frequency. Moss species with coverages of 2% to 4% can be common to dominant in boreal communities, although ribbed bog moss attains coverages as great as 40% in some boreal communities. Ribbed bog moss grows in open and forested wetland communities. In unforested northern communities, ribbed bog moss is found in sedge ("Carex" spp.) meadows, sphagnum ("Sphagnum" spp.) peatlands, heath-sedge fens, and willow ("Salix" spp.)-dominated fens. In forests, ribbed bog moss grows in the ground layer of boreal and subboreal white spruce ("Picea glauca"), black spruce ("P. mariana"), mixed