Trees of knowledge and trees of life have deep taproots in human culture. And if trees really had tongues, they might tell the story sketched in the prefatory chapters of Smithsonian Trees of North America: of dwindling habitats, precipitous climate shifts, and even extinction. But in the early 2000s, he began thinking about putting together a book about North American trees. Together with the detailed descriptions of each species, they aid in the identification of the common trees of the North American continent. And that is what Kress seeks to achieve with Smithsonian Trees of North America in photographs and words.