In 1804 Lewis and Clark lead a U.S. Army expedition across the Louisiana Territory to find a water route across the continent to the Pacific Ocean. One of the group's major goals was to map and describe details of the unknown area. President Thomas Jefferson, who authorized the expedition, also asked them to take note of the plants they saw. By the end of the two-year, 4,000-mile journey, Lewis and Clark had discovered more than 90 new plants previously unknown to scientists.
Types of Plants Collected
Specimens of bushes, flowers, trees, grasses and roots were collected, studied, and written about during the two-year journey. When the journey was finished, more than 200 botanical specimens survived the trip, far outweighing the number of other types of specimens Lewis and Clark gathered during the trip.
Since most of the Louisiana Territory was stilled occupied by Native Americans, Lewis and Clark had many opportunities to learn how the Indians used the plants they found. They discovered that roots of plants such as camas, wapato, and bitterroot provided important food sources, especially in the early spring. Oregon grape, salal, and wild ginger, among many others were also used as food. Fruits such as serviceberries, gooseberries and wild blackberries were eaten as found or more often dried for winter use.
Most the plant specimens Lewis and Clark gathered came from west of the Mississippi River. Sometimes they found more time to collect plants from certain areas. For instance, when the expedition was forced to camp for a month in Idaho during the return journey, Lewis used the time to carefully collect and write about as many plant specimens as he could. In doing so, he wrote one of the longest, most detailed plant descriptions of the expedition, describing the flower clarkia, also known as pink fairy.
As the expedition progressed, the group created caches of supplies and samples in order to lighten the load on their way to the Pacific Ocean. The expedition collected a number of plants that were cached at White Bear Islands in Montana. Unfortunately, springtime floods destroyed all of the specimens. The same thing happened with specimens, canoes and supplies cached at Camp Fortunate, Montana; only one specimen of golden currant survived the flooding.
After the Expedition
When the expedition returned to Washington, the plant specimens were sent to the well-known botanist, Frederick Pursh, for identification. When he finished examining the plants, he concluded that Lewis and Clark brought back more than 200 different specimens of which 90 were new finds. Many of these specimens may be seen at the Lewis and Clark Herbarium at the Academy of Natural Sciences in Philadelphia.