Bryophytes, more commonly known as mosses, are perfectly adapted to humid woodland environments, and are a vital component in the forest eco-system. A very ancient plant family, they reproduce through an archaic system of spores, and water is needed for their gametes to meet. They do not have roots, strictly speaking, but a system of rhizomes enabling them to be fixed to the soil, to a tree or a rock. They have the particularity of being able to survive when completely dehydrated in times of drought. This is called the reviviscence.