Bry-curious

Sphagnum denticulatum © Dom Hinchley

Sphagnum - a guide for the uninitiated

The immortal moss

Compared to the plants you might grow in your garden, mosses are very simple. As part of a group called Bryophytes, they don’t have roots or flowers and their leaves are often only one cell thick. Their simplicity is their strength; in dry conditions, they don’t wilt, but completely dry out. Some will stay like this for years until they are revived again by water. Mosses are so resilient that they can be found on every continent including Antarctica.

 

Carbon Storage

When plants and mosses grow, they take carbon dioxide from the atmosphere. When plants die, they rot and the CO2 is released once more. In an active bog, sphagnum keeps on growing, building up layer upon layer of vegetation. Due to the acidic conditions, plant material in a bog decays extremely slowly, locking away tonnes of carbon as long as the peat remains wet. Millions of years ago, under the right conditions, peat (which is about 60% carbon) was the first stage in the formation of coal.

Water Holding

It is not true that mosses need shade, however, they do need water and plenty of it. They only grow when they are wet. Sphagnum is often exposed to the sun all year round and has evolved a fantastic ability to hold water for as long as possible. Between its living, photosynthesising cells are dead cells whose sole purpose is to swell with water; there is water available to the living cells even in the hottest, driest summers. Able to hold up to 26 times its weight of water, sphagnum keeps the wetlands wet, maintaining the water table up to the surface.

War and Peat

Throughout history, sphagnum has been recognised for its amazing absorptive capabilities. Reports of Highlanders staunching their wounds after the battle of Flodden in 1513 hint at its uses. In more recent times, sphagnum played a major role in WW1, where it was gathered in huge quantities. High grade sphagnum was used in making bandages for the front line whereas lower grade was stuffed into bedding and pillows.