The Lewis and Clark Expedition (1804-1806) embarked on a monumental journey across North America. While its primary objective was to find a navigable water route to the Pacific Ocean, the expedition also held significant scientific goals. President Thomas Jefferson tasked the Corps of Discovery with documenting the vast, unexplored territories, including their diverse flora and fauna. This mission laid the groundwork for understanding the continent’s natural resources.
The Expedition’s Botanical Mission
Before the expedition, Meriwether Lewis received specialized training in botany and natural history from Dr. Benjamin Smith Barton at the University of Pennsylvania. He learned plant identification and preservation techniques, carrying reference books on the Linnaean system to describe plants scientifically.
Throughout their journey, the expedition collected, described, and preserved plant specimens. Lewis used a hand press to dry samples. Their detailed journals served as invaluable scientific records, containing descriptions of plants, their habitats, and how Native American tribes utilized them for food, medicine, and other purposes. This documentation resulted in a collection of over 200 plant specimens, many new to Western science.
Notable Plant Discoveries
The expedition formally documented numerous plant species previously unknown to Western science, introducing them to European classification. These discoveries provided crucial insights into the botanical diversity of the American West.
One prominent example is the Bitterroot (Lewisia rediviva), a small perennial herb named for Meriwether Lewis. Lewis encountered this plant in Montana in August 1805, noting its bitter taste and its importance as a food source for Native American tribes. Its scientific name, rediviva (“revived”), reflects its ability to regenerate from dry roots.
Lewis’s Monkeyflower (Mimulus lewisii, now Erythranthe lewisii) is a vibrant pink or reddish-purple flower found along mountain streamsides. Lewis documented this tall perennial forb near the Missouri River headwaters. Its showy blossoms were later named in his honor by botanist Frederick Pursh.
Lewis’s Prairie Flax (Linum lewisii), also known as Blue Flax, was observed in the Rocky Mountains. Lewis noted its potential economic value, as its tough stem fibers could be used for textiles, similar to cultivated flax. Native Americans wove these fibers into fishing nets and cordage. This perennial produces delicate, clear blue flowers.
The Oregon Grape (Mahonia aquifolium or Berberis aquifolium) was described by Lewis near the Columbia River’s Cascades. This evergreen shrub has glossy, spiny leaves and bright yellow flowers that yield blue fruits. Lewis initially referred to it as “mountain holley” due to its leaf resemblance.
Lasting Botanical Impact
The botanical work of the Lewis and Clark Expedition profoundly impacted the understanding of North American flora. The more than 200 specimens collected represented a significant expansion of known plant species. These specimens, along with Lewis’s detailed field notes and descriptions, provided foundational data for subsequent botanical studies.
Upon the expedition’s return, the collected plant specimens were sent to Philadelphia for formal classification. Frederick Pursh, a German botanist, studied and described many of the plants. His two-volume work, Flora Americae Septentrionalis, published in 1814, included descriptions and illustrations of 124 of the Lewis and Clark specimens, becoming a standard reference for 19th-century botany.
Today, nearly all surviving Lewis and Clark plant specimens are housed at the Academy of Natural Sciences in Philadelphia, forming the Lewis and Clark Herbarium. Their collection provided a baseline for understanding the ecological landscape of the American West. The expedition’s records and collected plants continue to serve as a valuable resource for naturalists and scientists, illustrating the biodiversity of the continent before extensive European settlement.