Sphagnum squarrosum

Sphagnum Squarrosum is circumpolar in its distribution in the northern hemisphere. It is a common associate to mesotrophic fens, where it forms carpets and small hummocks. It can occur in both shaded and exposed habitats. In the field, this species is easily  identified by its obvious squarrose  branch leaves, large capitulum, and prominent terminal bud. Most commonly, this species is confused with S. girgensohnii, S. palustre, and S. teres. The squarrose branch leaves make it unique among S. girgensohnii and S. palustre, however, S. teres in its green forms can look similar. The best way to distinguish these two species is by the branch leaves. S. squarrosum has branch leaves 1.9 - 3mm long, while S. teres has branch leaves 1 - 1.5 mm long. Microscopically, these differ significantly in the porosity of the branch hyaline cells. S. squarrosum has smaller ringed pores on the concave surface, and un-ringed pores on the convex surface of the branch leaf hyaline cells, while S. teres has un-ringed pores on both surfaces of the branch leaf hyaline cells. 

Sphagnum girgensohnii is circumpolar in its northern hemisphere distribution. It is tolerant slightly more acidic conditions than S. squarrosum, however, it is commonly mixed in with S. squarrosum carpets and hummocks. It will also form low hummocks, and carpets on the fringes of bogs and fens from low to middle elevations. In the wet foothills and valleys of the Cascades and Olympics this is the most prominent sphagnum species as it is common in old growth forested depressions, northern aspects of narrow drainages, ditches. Sphagnum girgensohnii is most easily identified in the field by its long, tapering spreading branches which cover the wiry, robust stem. This species is always green and unlike other species in its sub-group (acutifolia), will never have any red coloration. In less acidic parts of fens, it will frequently be found along-side S. fimbriatum which is a much more slender, and smaller species.  For further details: Sphagnum girgensohnii also see Sphagnum girgensohnii anomaly.  

Sphagnum palustre is a species that often can be confused with other members of the sub-group sphagnum. It can have tremendous phenotypic plasticity throughout the northern and southeren hemisphere. In the Puget Sound region, and especially within forested fens, this species can be all green aside from its brown stem. In the fall and winter, the capitulum will turn ochre-pink in partially exposed habitats, then turn more green-yellow as summer approaches. S. palutre generally occupies the edges of forested nutrient rich fens where it will form large hummocks, up to 3'. Of the species it is most confused with (S. papillosum, S. centrale, S. magellanicum, and S. henryense) it can really only be accurately identified with microscopic examination because it can assume the form of many species in the sub-group sphagnum. A more detailed description of S. palustre will be added soon. 

Sphagnum capillifolium  is best known for its distinctly hemispheric capitulum. It can be nearly all green in shaded forms, then with intermediary coloration trending towards sites with full exposure where it will be all red. Unlike the species listed above, Sphagnum capillifolium establishes in nutrient poor fens and paludifying forests. It forms very large, tight, expanding hummocks (sometimes over 4'). in sparse, or younger populations, it will occur with S. girgensohnii and S. squarrosum.  S. rubellum  closely resembles S. capillifolium, however, it is generally is a carpet, and low hummock former. It will occupy the lower portions of S. capillifolium hummocks. In this case a close examination the capitulum being less hemispheric, branches weakly 5-ranked, and the cylinder of the branches often seen through the less dense leaves, the differences in these species will become clear. In western Washington, King's lake NAP and Shadow lake preserve, as well as many other basin bogs have iconic populations of S. capillifolium. For a more detailed description, see Sphagnum capillifolium.