The Lewis and Clark Expedition, a monumental journey across the North American continent from 1804 to 1806, was primarily an exploration of uncharted territories. Beyond charting new lands and seeking a water route to the Pacific, a significant objective was scientific discovery. President Thomas Jefferson, a keen enthusiast of natural history, tasked Meriwether Lewis and William Clark with meticulously documenting the flora, fauna, and geography of the vast, unexplored regions they would traverse. This directive laid the groundwork for a substantial botanical undertaking, aimed at expanding the known understanding of North American plant life.
The Botanical Mission and Methods
President Jefferson provided Meriwether Lewis with specific instructions for scientific observation, emphasizing the detailed recording of plants, animals, and geological features. Lewis, who received training in botany from prominent scientists like Benjamin Smith Barton, was well-prepared for this task and carried essential tools, including a plant press and paper, to preserve specimens for future study. The expedition systematically collected plant samples, pressing and drying them between sheets of paper to prevent wilting and decay. Lewis also maintained meticulous journals, noting plant characteristics, habitats, and traditional uses by Native American tribes. This rigorous documentation was challenging, particularly in humid environments like the Pacific Northwest, where preserving specimens required constant attention.
Notable Plant Discoveries
The expedition formally documented numerous plants previously unknown to Western science. One such discovery was the Bitterroot (Lewisia rediviva), a small perennial herb with fleshy roots, found abundantly in western Montana. Meriwether Lewis first collected this plant in July 1806 near Travelers’ Rest. Native American tribes, including the Shoshone and Flathead, highly valued the bitterroot as a food source, peeling and boiling its roots.
Another significant discovery was Camas (Camassia quamash), a member of the lily family characterized by its grass-like leaves and blue to deep violet flowers. The Nez Perce people introduced Lewis and Clark to its edible bulb in September 1805, which was a crucial food source after the expedition’s arduous crossing of the Bitterroot Mountains. The bulbs were cooked in earthen kilns, transforming complex carbohydrates into a sweet, fructose-rich food. However, the expedition members initially experienced digestive issues from consuming it in large quantities, unfamiliar with its fibrous nature.
The Oregon Grape (Berberis aquifolium), first noted by Lewis in February 1806 near the Columbia River’s Cascades, was also documented. This shrub features holly-like leaves and yellow roots. Indigenous tribes along the Columbia River utilized its roots to produce a yellow dye, which was important for coloring woven materials. The plant was also used for food and medicine.
The Enduring Botanical Legacy
The botanical findings of the Lewis and Clark Expedition significantly expanded the understanding of North American flora. They collected and documented approximately 240 different plant species, with 178 of these being new to Western science at the time. These specimens and the detailed journal entries provided an unprecedented glimpse into the biodiversity of the American West. Upon their return, the collected plant specimens were entrusted to Frederick Pursh, a German-American botanist. Pursh played a pivotal role in classifying and publishing these discoveries in his two-volume work, Flora Americae Septentrionalis, released in 1813. This publication formally introduced many of the expedition’s findings to the scientific community, providing scientific names and detailed descriptions. The work of Lewis, Clark, and Pursh laid a foundational baseline for subsequent botanical expeditions and studies, contributing immensely to the systematic documentation of the continent’s plant life.