[♪ INTRO].

At first glance, moss might seem kind of boring. You might’ve even stepped on some during your last walk without even noticing.

But hiding beneath moss’s plain exterior is a hidden superpower: the ability to heal. And not just in some abstract sense:. During World War I, moss was used for packing the wounds of countless injured soldiers, saving lives on the front lines.

Mosses contain a number of chemical compounds that help them survive and protect them from being munched on by predators. For example, sterols help them adapt to changing temperatures; amino acids improve their consumption of nitrogen; and antioxidants help them deal with the stressors in their environment. But the presence of these substances also helped mosses, specifically sphagnum moss, come to the rescue in a big way during World War I.

At the height of the war, providing enough bandages for British troops was a critical problem. A lot of the cotton wool traditionally used for bandages was being diverted to the manufacture of guncotton, a smokeless, highly flammable alternative to gunpowder. Because British doctors couldn’t get enough bandages and sterile supplies to keep wounds clean and covered, soldiers' injuries were becoming infected, leading to sepsis and death.

And that’s where moss enters the story. People in Germany were already using it to treat wounds, and, soon, so was the British Army. It might seem out of place in a war defined by new technologies like the airplane, but mosses have been used to pack wounds for hundreds of years.

And sphagnum moss grows with abundance in both Germany and the United Kingdom, so it became just one more resource to bring to bear during the war. One of the keys to moss’s success is its incredible absorbing abilities. Moss is actually 90% dead plant material, and those dead cells help it absorb up to 22 times its weight in liquid.

In fact, it performed better than cotton bandages at absorbing blood and the other substances oozing from soldiers’ wounds. The other reason sphagnum was so successful as a bandage is because it creates an acidic, sterile environment. The moss’s cell walls are built from acidic compounds, up to 30 percent of its dry weight is uronic acid.

The acidic nature means the cell walls of the moss have lots of hydrogen ions very loosely bound to them. Because they’re connected only through loose chemical bonds, these protons will easily change places with other positively-charged ions in the surrounding environment. And, since that environment, like, say, soil, or the inside of a wound, now has an excess of loosely-bound hydrogen ions, it becomes more acidic itself.

Peat bogs are full of sphagnum and this acidifying process is part of what makes them so good at preserving things like bodies. But moss’s acidity also creates a sterile environment because it inhibits the growth of bacteria. And that acidity is just one element of moss’s sterilizing property.

As I mentioned before, mosses contain many substances that are useful in their survival, but they also help prevent bacterial, viral, and even cancerous growth in humans. Researchers have extracted these compounds and shown them to be successful against preventing the growth of multiple bacterial strains, including E. coli, Bacillus, Pseudomonas and Staphylococcus. Bacillus and Staph infections were particularly common during the first world war, as soldiers rarely had the chance to get clean during trench warfare.

During the war, moss drives were held in the UK, Canada, and the United States as the demand for bandages soared. In 1916 alone, Ontario provided millions of bandages made exclusively from moss. And by 1918, one million bandages a month were being sent from Britain to hospitals in Europe and beyond.

Not only did moss bandages heal soldiers’ wounds, they were a renewable resource. Moss could be collected from nearby bogs and, as long as the peat beneath wasn’t disturbed, the moss could grow back. Now, we don’t use moss as bandages today, in part because we have antibiotics.

But also, harvesting moss is a tremendously labor-intensive process. And that’s probably for the best, because moss bogs are huge reservoirs of stored carbon that play a major role in keeping our climate stable. If the peat layer is exposed, it can dry out and catch fire, releasing all that stored carbon in the blink of an eye.

Not to mention, mosses aren’t well-studied or -understood, even though they are one of the oldest and most diverse lineages of plants. The same properties that make them really great at wound healing make them important engineers of ecosystem biodiversity. So the least we can do is protect them, after all, we owe them for all the lives they’ve saved.

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