When Thomas Jefferson handpicked Meriwether Lewis to lead the Corps of Discovery on its exploration of the land west of the Mississippi River, he tasked Lewis and his company with gathering native plant specimens along the way. One volume of the expedition’s journals, Jefferson instructed, should be dedicated to science-worthy descriptions and classifications of the plants the Corps collected and pressed to preserve. In Chasing Lewis’s Monkeyflower, Elizabeth Adelman recounts the thrilling, never-before-told, two-hundred-year saga of finding, losing, and finding again the wild plant specimens collected on the United States’ first official exploration west. In the years that followed Lewis’s return, ambition, deceit, theft, wealth, debt, alcoholism, loss, suicide, serendipity, and stubborn persistence crossed the plants’ paths in Philadelphia, New York, and London. Today, specimens of nearly two dozen plants are still missing—one of which is Lewis’s monkeyflower, Erythranthe lewisii, syn. Mimulus lewisii. Adelman has given us a plant’s-eye perspective on a fabled American story, and has composed the first work detailing the cavalcade of places, practices, and people who came into contact with these precious specimens. The result is a highly entertaining detective story and a fascinating chronicle of an unexplored byway through history.