One of the United States' most prominent botanists, James L. Reveal has joined forces with A. Scott Earle (a retired surgeon and professor) to follow the Corps of Discovery's trail, focusing on the plant specimens that Capt. Meriwether Lewis "collected for Mr. [Frederick] Pursh," President Jefferson, and other scientists of the early 19th century.

Earle's and Reveal's seasonal color photographs illustrate complete botanical descriptions of each plant, which are accompanied by quotes from Lewis's journal about it, along with comments from scientists of his day and since.