Widecombe-in-the-Moor and helping the wounded is a moss made in Devon.
Moss only grows in the presence of three things: light, water and nutrient. I’m being exacting here, it needs these three things at the exact same time or it will not grow. Remove one of these things and it will go into dormancy.
It only grows in the light, so no metabolism whatsoever at night (unlike most plants). It has no roots and can take no moisture from within the substrate, no nutrient, either.
Everything the moss uses to grow comes from the surface it is growing over, or whatever lands on the moss itself. This gives the moss the ability to grow on incredibly acidic soil, since the substrate doesn’t affect the moisture that the moss actually absorbs.
And absorbs is the right word. Even wet moss can soak up bucket fulls of water. Sphagnum is a name applied to some thirty species of moss, but all share key qualities: they have two different types of cell 1. normal plant photosynthesising cell and 2. barrel shaped water storage cell that soaks up water.
Sphagnum must be in the presence of water, or it will shut down, go into this state of non-activity. The same shutdown that happens on dry days also begins as soon as light is too dull to register.
Moss shuts down if any of those three things are not present at that exact moment.
All sphagnums can absorb many times their own weight in water. So they are very acidic, and inhibiting of infection, and also very absorbent.
They also are as soft as any bandage of the time, so during The First World War the people of Widecombe put to good use this extraordinary environment. They harvested moss to treat battlefield wounds.
The next time you visit Widecombe, take a look at the mossy stone walls around the village.