Nutritional Use
Phloem of pine trees has been used in Finland as a substitute food in times of famine, and even in good years in the northeast, where supplies of phloem from earlier years helped stave off starvation somewhat in the great famine of the 1860s. Phloem is dried and milled to flour (pettu in Finnish) and mixed with rye to form a hard dark bread. The least appreciated was silkko, a bread made only from buttermilk and pettu without any real rye or cereal flour. Recently, pettu has again become available as a curiosity, and some have made claims of health benefits. However, its food energy content is low relative to rye or other cereals.
Phloem from silver birch has been also used to make flour in the past.
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