Common Name: Sphagnum Moss, Peat Moss, Bog Moss, Sphagnum Peat Moss – One of the few plants that derives its common name from its scientific generic name. Moss is from a Germanic word meaning ‘swamp’ which is attributed to the Sanskrit mūtra which means ‘urine’ which is likely an anomaly but which may be due to acidity. The Latin word for moss is muscus.
Scientific Name: Sphagnum spp – Sphagnos is sometimes listed as the Greek word for a spiny shrub or a kind of moss but was likely a more general term for an unknown plant; its etymology is uncertain. The word carries over to Latin as a kind of lichen. Spp is an abbreviation for species and is used to indicate generality of all species rather than any one in particular.
Potpourri: Sphagnum mosses are probably the best known of the bryophytes – the phylum of mosses, liverworts and hornworts – presumed to have originated from pioneer green algae that emerged from Precambrian seas about 600 million years ago. The single cell thick leaves of most mosses can absorb water directly from the atmosphere, converting light to nutritive hydrocarbons for growth and reproduction in situ. In the absence of the necessary vascular plumbing evolved by higher forms to move water and minerals upward against the force of gravity and to move nutrients from photosynthesis downward to the anchoring roots, the bryophytes retained the simple ground hugging physiology that they first defined. As exemplars of Occam’s razor lex parsimoniae that simpler is better, mosses thrive in moist shaded niche habitats and prevail across vast areas where more advanced plants are unsuited; this is most especially true of the Sphagnum mosses.
The synonymy of sphagnum moss and peat moss is due to the historical pragmatics of their association. The word peat is of ancient origin and is thought to be of Celtic provenance meaning ‘piece,’ contextually the two are linked by the ancient practice of cutting pieces of vegetative turf material growing in bogs for use as a fuel in prehistoric Europe. As humankind advanced to the point of assigning names and taxonomic relationships to plants, the name given the primary constituent of the areas where pieces of peat were extracted was sphagnum; sphagnum peat moss is sometimes used to further conflate the two. As a matter of precision, only the growing plant at the surface of the bog is sphagnum moss while the dead and compacted mass beneath it that includes sphagnum and parts of other plants is what was (and still is in places) cut and burned as peat fuel. However, the evolution of species over time according to survival is the real reason that sphagnum is peat; it creates the sphagnum peat bog that is its habitat.
A bog is loosely defined as a wet spongy area with a characteristic flora of sphagnum, sedges and heath and more specifically as a low-lying area having a thick layer of peat; bogs instantiate the moors of England and Scotland. The word bog is also of Celtic origin meaning ‘soft;’ these areas are now sometimes called peatlands. According to the International Peatland Society, there are about 400 million hectares of peatland globally which is about 3 percent of the earth’s terrestrial surface, almost entirely in the northern reaches of Eurasia and the Americas; the areas glaciated during the Pleistocene Epoch over 10,000 years ago that now have an annual mean temperature below 50°F. Due to the packing factor inherent in sphagnum bog propagation, it is estimated that peatlands contain about one third of all terrestrial soil carbon. A bog is one type of wetland. The other types of wetlands are marshes which are dominated by shrubs, swamps which are dominated by trees, and fens, which are bogs with high levels of dissolved minerals. Bogs occur because sphagnum establishes a chemical habitat that it is suited to and which excludes invasion by most fauna and fungi making it essentially axenic, devoid of all other species.
The peat bog environment is established and maintained by the sphagnum moss. Bog water is acidic at a PH of between 3 and 4.5 (about the same as orange juice) due to sphagnum absorption of cations (positively charged ions) like magnesium and calcium which results in the release of hydrogen ions – which lower the PH – and in a depletion of mineral resources; peat has less than 1.0 percent nitrogen and less that 0.1 percent phosphorous and potassium, the three primary elements plants need for growth. As sphagnum lives and dies over its life cycle, successive generations build up in the water-logged depressions under the photosynthetic canopy to restrict the access of oxygen. As a tertiary measure, sphagnum mosses create a variety of phenolic compounds as allomones, one of which is suggestively named sphagnol, to further exclude intrusion. The combination of acidity, low nutrients, the lack of oxygen and chemically active compounds are all evolved processes to exclude the bacteria and fungi of decay to ultimately create the peat moss prized for fuel.
In many references, peat moss is considered a precursor to lignite, the brown, cheap or dirty coal that has long been calumniated for its poor heat capacity – more needs to be burned relative to energy extracted which in turn leads to a higher amount of carbon dioxide, the bane of global warming. Lignite coal, when buried under sediments and compressed by geologic forces, becomes bituminous coal (at a ratio of about 3 feet of lignite to 1 foot of bitumen) which in turn can become the hard rock anthracite coal by orogenic forces (such as those that formed the Appalachian Mountains to create the coal beds of eastern Pennsylvania). The coal beds were initially deposited during the Carboniferous Era (its name a toponym for carbon creation) which extended from 350 to 280 million years ago characterized by swampy areas burgeoning with giant ferns and primitive trees that were not appreciably depleted by scant fauna, bacteria or fungi lived and died to accumulate in substantial thicknesses. These “peat” formations had nothing to do with sphagnum moss, estimated to have evolved a scant 10 to 20 million years ago. The peat bogs of today are not the coal fields of tomorrow. The peat as a coal precursor is a broadening of the term peat to include any accumulation of vegetative matter by deposition over time; some type of moss played a role, probably a small one – but not sphagnum moss.
The sphagnum mosses are distinct from their closest relative bryophytes in having a unique structure of small, branching and crowded leaf-like structures which are frequently, though erroneously called leaves (they are unicellular and lack the vascular veins of true leaves). The plant structure has been metaphorically described as disheveled, like a bundle of Alpine edelweiss with a pale green hue. Sphagnum taxonomy is not well established and global estimates for the number of species range from 135 to over 300 with some 50 indigenous to North America. Taxonomically, sphagnum mosses are alone in the class Sphagnopsida, the order Sphagnales, the family Sphagnaceae and the genus Sphagnum; there is not consensus agreement as to whether they are a class, an order, a family or a genus. From the anthropocentric perspective, what further distinguishes sphagnum mosses is their ability to absorb up to about 25 times their weight in water, a consequence of their physiology. Sphagnum leaves consist of alternating small and large cells containing chlorophyll and protoplasm. As the plant ages, the larger, or hyaline cells lose their autotrophic capability, essentially becoming cellular cisterns with thicker cell walls and circular intra-cell accesses; the smaller, green chlorophyllose leaves retain photosynthetic capabilities as evidenced by verdancy. The evolutionary forcing factor that favored this “intelligent” design was the retention of acidic water to protect the sphagnum plant from competition to thereby promote its longevity; the end result a superlative botanical sponge of cellulose chambers.
The prodigious water absorptive capacity of sphagnum mosses and their inherent antibiotic properties commend them for numerous applications. Historically, peat moss has provided an ersatz watershed for the transport, soil conditioning and transplantation as needed for horticulture’s moisture management. It is also used whenever water retention is desired in many other agricultural applications such as mushroom cultivation and tree grafting. In what may come as something of a surprise in the era of energy alternatives including everything from renewable wind to irredeemable tar sands, about half of all peat moss harvested is used for fuel, either by burning directly or by conversion to synthetic gas. This is especially true in northern Europe, notably Finland (7% of total energy production) and Ireland (3 million tons burned annually), where bogs persist and there are few viable alternatives. The economics of the ever-expanding global population drives innovation technologies; peat moss is collected to make pulp for paper manufacture, combined with concrete to make “peat-crete,” and combined with wood to make “peat-wood” as alternative greener construction materials. While hardly ecological, peatlands have also been used for wastewater treatment, taking advantage of the absorptive properties to retain toxic heavy metals. However, more interesting if less obvious are the uses of sphagnum moss for its antimicrobial and antifungal properties.
Vulnerary practices have changed drastically over the centuries as the role of germs and inflammation became manifest and sterile cotton bandages came into use to staunch wounds. In the absence of gauze compress, sphagnum moss has historically sufficed. It is written in a 1014 Gaelic account that the Irish wounded from the battle of Clontarf between the invading Norsemen and the Celtic chieftains led by King Brian used moss to stuff their wounds. It was similarly used in Scotland and by the Sami people of Lapland. It has been observed that wounded deer seek out sphagnum beds for rehabilitation. Sphagnum moss as battle or surgical dressing should not come as any surprise, as it can absorb twice as much fluid as cotton in addition to providing a degree of antimicrobial protection. In the late nineteenth century at the dawn of modern medicine, the Germans began using sphagnum moss as a surgical dressing. The subsequent carnage of the First World War taxed the medical resources on both sides of the western front trenches, resulting in extraction of sphagnum from moors in Yorkshire and Scotland by war workers for use at the front.
The sphagnum moors of England and Scotland figure prominently in literature and folklore; Emily Brontë’s Wuthering Heights is a case in point. While the expansive inhabitable wasteland bogs are tenebrous in their own right, the chemistry engendered by sphagnum adds an additional element of mystery and intrigue: the bog people. Low temperature acidic water that is devoid of oxygen (anaerobic) acts as a skin preservative and bone dissolver, yielding cadavers that retain their original features stained to a dark brown by what amounts to pickling. Hundreds of bog bodies have been discovered in northern Europe in an arc from the British Isles to Scandinavia, the oldest dating from 8,000 BCE. Many are found with wounds or constraints suggesting ritual murder or perhaps sacrifice to prehistoric animist spirits. The natural preservative of sphagnum bogs was apparently well known to the autochthonous peoples of Europe, who used the bogs to store “bog butter,” caches of dairy fat (butter) and animal fat (lard), probably as an emergency ration for use in times of famine. So far, no zombies.