According to
Atlas Obscura:
A xylothek (from the Greek for tree, xylon, and storing
place, theke) is an object where the container is a fundamental component of
the contents. The term usually refers to books that are both made of wood and
filled with wood specimens…. Xylotheks were particularly popular in late 18th
century and early 19th century Germany. In these constructions, each book in
the xylothek was made out of a particular type of wood, the spine covered with
the corresponding bark and decorated with associated moss and lichens. Once
opened, the book would reveal samples of dried leaves, flowers, seedlings,
roots, and branches, with a special compartment in the spine holding a written
description of the species' biology and use.
