Uses of mosses and liverworts
In the modern world the economic uses of mosses and liverworts are not immediately obvious. But they do have an important and subtle ecological role, both in water-retention and stabilising mobile surfaces like landslips, scree slopes and sand dunes. Examination of almost any handful of moss will also reveal another important ecological role – that of providing shelter and humidity for a remarkable diversity of invertebrates. This is an integral part of the food web in many of our important habitats.
In the past, mosses were used as an easily obtainable and multi-purpose packaging material. Wads of mosses were used to line pits, probably for the storage of vegetables, and also as stuffing for bedding, along with bracken and straw. ‘Ötzi’, the 5,000 year-old body of a hunter found in a glacier in the Tyrol, had large quantities of moss stuffed inside his clothing. This was possibly for insulation but more probably as packing material for his food and this kind of use was probably widespread. It is likely that moss has a long tradition of use for ‘personal hygiene’, a tradition kept up by desperate hill-walkers today. Moss was also used as a caulking (a filler) by Bronze and Iron Age boat-builders and this use continued up until the early 19th century in northern Scotland. Similar use was made of moss to pack the walls of stone houses, particularly near the chimney to keep out the wind and prevent the heat from setting fire to the wooden frame. In the Victorian era, moss was used around the base of potted plants and in flower arranging when ‘moss-gathering’ was a small industry. This industry is now showing signs of a significant revival with ‘moss’ being harvested from plantation woodland for the horticultural trade.
The most important mosses in economic terms are Sphagna, the bog-mosses. In Scotland the dead remains of Sphagna are the main constituent of the peat which covers some 10% of our land. Peat was an important source of fuel over much of the Highlands and peats are still cut as fuel in much of the north and west. Peat has formed over thousands of years when the rate of plant growth has exceeded that of decay. The rate of decay was slowed by the water-logged nature of the ground and the acidity of the ground-water. Peat accumulation started as the climate became wetter soon after the ice retreated some 10,000 years ago. This sometimes reaches 80 centimetres per 1,000 years.
When you walk over a bog, you are walking on water. Over 85% of the bog, by weight, is water, much of it held in the special dead and empty cells which make up most of the leaf of the Sphagnum plant. This characteristic is shared by peat which is often 90% water before it is dried out for burning. Then it has an energy output of about half that of coal but much more than wood. The water-retaining quality of Sphagnum peat is also much prized by the horticultural industry. Peat is still extracted by milling off the surface layer and is sold in garden centres across the country.
This absorbent quality, plus its mild antiseptic properties, also gave rise to a little-known industry in Scotland, the harvesting of living Sphagnum for use as wound dressings. The value of Sphagnum for covering wounds has been known for centuries. But it was not until the early 20th century that there was widespread commercial production, reaching its peak in the First World War, when some one million Sphagnum dressings per month were used by the British forces. Sphagnum was harvested, cleaned and dried and sent off in bales to factories where it was sewn up in fine muslin and sterilised. The centre of production in Scotland was in the Borders and Dumfries and Galloway, but collecting went on over much of the country.
Very few mosses and liverworts have names that are in common usage and the different species are usually referred to by their Latin names by botanists and just as ‘moss’ by almost everyone else. The name ‘liverwort’ comes from the supposed resemblance of thalloid liverwort to the liver and has its origin in the ‘Doctrine of Signatures’ of the old apothecaries, whereby similarity of shape was believed to confer healing powers. A list of common names for bryophytes has now been compiled, all but a few being recent inventions.
The Gaelic term mòine, a mossy place or a mire, often appears as a place name on maps but there is also a generic term for moss, còinneach, and it seems likely that this usually referred to Sphagnum, which was important because it was a useful plant. The red forms of Sphagnum were called còinneach dhearg, red moss, and had some therapeutic value in the Western Isles:
“When they are in any fatigued by travel or otherwise, they fail not to bathe their feed in warm water wherein red moss has been boiled, and rub them with it on going to bed.” Martin Martin, A description of the Western Islands of Scotland, 1703.