Then place the dried moss in a very humid atmosphere e.g. resting on wet paper towel under a plastic bottle 'propagator'. Watch the moss carefully over the next few hours. Then reweigh after it has absorbed water. The increase in mass will be due to the absorption of water. Calculate this increase as a percentage of the mass of the dry moss.
Some mosses give a surprisingly high figure.
This moss, which was used to help stop the bleeding of wounded soldiers during the both World Wars, also has antibiotic properties. Use a microscope to examine the leaves of the moss you used in 4. Many gardeners find it hard to kill the mosses in their lawns. It is often suggested that the addition of sand to a lawn will kill the mosses. We are grateful to Christine Preston, Education and Interpretation Officer, University of Cambridge Botanic Garden for helpful suggestions on this activity.