Each "book" describes a certain tree species and is made out of the actual wood (the "covers"). The spine is covered by the bark, where mosses and lichens from the same tree are arranged. "Books" of shrubs are covered with mosses with split branches on both covers and spines.
Inside there are dried leaves, flowers, fruits, seedlings, a piece of the root, cut branches, seeds - similarly arranged in every "book". In a compartment inside the spine lies a delicately written description of the tree, its biology and its practical use.
SLU Libraries - The Wooden Library in Alnarp
(via ::: wood s lot ::: )