Sphagnum is a genus that comprises one of the major groups (superclasses) of the largest phylum of mosses (Bryophyta) generally found in boreal areas in the Northern Hemisphere (although diverse species also occur in tropical and subtropical areas, and in the Southern Hemisphere), best known as a typical species of bogs, coniferous swamps, and fens, and used horticulturally (as a plant growing medium or soil amendment), as a biofuel (traditional in Ireland), and to flavor alcoholic beverages (whisky and Scotch), among other products.
The Sphagnum genus contains roughly 135 species, although classifications have varied considerably in the number of species recognized. All species display a distinctive branch arrangement, with 3 or more fascicles (groups) of branches produced with every 4th leaf. Within a fascicle, at least 2 branches hang downwards, pressed close to the stem, while 1 to 3 are held out, diverging from the stem.
Sphagnum mosses are a dominant component of bogs and other wetland ecosystems, and affect important ecological processes. They tend to acidify their environment, and thus to direct future succession. The presence of Sphagnum deposits and spores has been used in paleoecological studies as an indicator of past climates and ecological conditions. This group of mosses has a tremendous water-holding capacity, potentially retaining 25 times their dry weight in water, which modifies spring runoff in vast stretches of permafrost in the Arctic; however, when permafrost melts, the Sphagnum becomes saturated and may suddenly release large volumes of water.
Sphagnum, often referred to as peat or peat moss (although “peat” includes various species of partly decayed vegetation), is widely used in horticulture, as a planting medium, mulch, soil conditioner, and for grafting trees and cultivating mushrooms. However, nearly half of the peat harvested annually is used for fuel; it is an important fuel source in northern European countries including Finland, Germany, Ireland, Poland, Russia, and Sweden. Peat may be burned directly or converted to other burnable fuels, including methane, ethylene, natural or synthetic gas. Sphagnum is also used as fiber or pulp for paper manufacture, and is a component of recently developed construction materials, including “peatcrete” (peat mixed with concrete, then pressed with Portland cement and water and cast or molded) and “peatwood” (mixed with phenolic resin and molded).
Sphagnum peatlands have been used for wastewater treatment. When sewage is discharged to an active peatland, Sphagnum can absorb toxic heavy metals, oil spills, PCP (pentachlorophenol), microbes, and excess nitrogen and potassium from eutrophic river water.
Sphagnum has also been used in diverse ways in the past. Native Americans used it for diapers, and it was used during World War I in bandages instead of cotton—both applications took advantage of its absorbency, but also its antimicrobial and antiviral properties, which have been confirmed in recent studies. It has been used to stuff mattresses, pillows, furnishings, and as insulation, and in sanitary napkins and boot liners (to absorb moisture and odors), as animal bedding, or mixed with molasses as livestock feed. It can be mixed with alkaline to produce a brown dye. Scotch and Irish whisky are flavored by peat when germinated malt (or barley) is dried over peat fires.
Threats to Sphagnum peatlands are outlined in the “Threats” section.
(Anderson et al. 2009, Crandall-Stotler and Bartholomew-Began 2007, Crum 1988, Crum and Anderson 1981, Glime 2007, McQueen and Andrus 2007, Wikipedia 2012.)