Lichen

Lichen is not a plant, rather a composite organism consisting of fungus and algae. A fungus forms the lichen itself and inside the fungus there are algae, or blue-green bacteria, that produce nutrients. It is a bit like in an old-fashioned relationship, where one partner builds the house and protects the family from wind and weather, whilst the other partner cooks. A common one is reinlav, or reindeer lichen; as the name implies, it is a food source for reindeer during the winter season. Lichen contains few nutrients, so the reindeer must try to use as little energy as possible until the mountain grows green again in the spring. Lichen has been used in human consumption, for example Icelandic lichen was often mixed into bread dough. Lichen is very sensitive to air pollution. Where a lot of lichen thrives, such as here at Skinnarbu, there is little air pollution. We can assume that where there is less lichen, for example in the middle of Oslo, there is more exhaust and smoke. You can check your environment when you get home. Do you find comparatively more or less lichen on the trees?