Cladonia Rangiferina, also known as reindeer lichen, is a type of lichen found in the arctic and subarctic regions of the world. This lichen is commonly used as a winter food by caribou and reindeer. It is also used for medicinal purposes and as a source of dye. Cladonia Rangiferina has several synonyms, including Cladina Rangiferina, reindeer moss, and caribou moss. Another synonym for this lichen is Cladina Alpestris, which is found in alpine regions. Despite its name, Cladonia Rangiferina is not just a food source for reindeer, but also plays an important role in the ecology of the arctic tundra.