Lichen
Lichen are the main winter food for reindeer. The deer can get at shrubby lichen under the snow. In summer they have much more choice of food. Some lichen are eaten by humans. A kind of lichen, which is called Iwatake in Japanese and Seogi in Korean language, is collected from cliffs, and used in various Korean and Japanese foods. Lichen have a high level of acid. Care must be taken, as there are at least two kinds of lichen that are toxic.