We all know that books are normally printed on trees - that is, on paper. But there's at least one book printed IN trees. In other words, using a tree font! Each letter corresponds to a different type of tree. The title is About Trees and the creator is Katie Holten, an Irish artist.

For the Trees font, which was created especially for the book, Holten delved into her archive of New York City tree drawings, created 10 years earlier. "I wrote out the alphabet, A through Z, and then realized I could match a tree that had the same letter: A for apple, B for beech, C for cedar." The book contains tree-themed works by prominent authors. The text of each piece appears in English alongside a Trees translation.

The font is free to download. You may want to "plant" your own message! (NOTE: a period is represented by an acorn).