President Thomas Jefferson organized America's first official exploration of western territory overland to the Pacific. Leading the dozens of men in what was called the Corps of Discovery were Meriwether Lewis and William Clark. Besides searching for the fabled "Northwest passage" to the Pacific, the expedition was expected to record the geology, animals and plants they encountered along the way. More than 300 new plants were discovered on the 2 1/2-year-long journey to the West Coast and back.
Lewis documented his first specimen before the expedition left St. Louis, according to the U.S. National Park Service. As he and Clark were busy making preparations in St. Louis prior to setting out in March 1804, Lewis prepared cuttings of an Osage orange tree (Maclura pomifera). Its name refers to the Indian tribe that inhabited the tree's narrow native range of the Red River Valley of Oklahoma and Texas. Many deciduous trees are mentioned in the expedition's log, including the bigleaf maple, Rocky Mountain maple, black hawthorn, narrowleaf cottonwood and Oregon white oak. Evergreens discovered on the trip include the lodgepole pine, mountain hemlock, Western red cedar, whitebark pine and Pacific yew.
Lewis's mockorange (Philadelphus lewisii) was collected by the expedition in 1806 and has since become the state flower of Oregon. Named for Meriwether Lewis, its showy white flowers bear a resemblance to those of the orange tree, and also emit a sweet scent reminiscent of orange and jasmine. Native to Washington, Oregon, Idaho, Montana and California, this deciduous shrub reaches 3- to 10-feet tall, according to the U.S. Department of Agriculture. Other shrubs discovered by the expedition include the common snowberry and the California rhododendron.
The Lewis and Clark expedition is responsible for the discovery of many American wildflowers west of the Mississippi. One of the best known, the purple coneflower (Echinacea augustifolia), was the most widely used medicinal plant of the Plains Indians. Echinacea served as a pain reliever for all sorts of conditions, and was eventually adopted as an all-purpose remedy by white settlers. Other flowers recorded in the expedition's journals include red columbine, purple trillium, Jacob's ladder, prairie rose and mountain lady's slipper.
The expedition also sent on or returned with seeds from a variety of food crops, which Thomas Jefferson planted in his gardens at Monticello. The yellow arikara bean, named for the Dakota Arikara tribe from whom Lewis received the seed, can be harvested when young as a snap bean or used dried in soups or stews. Jefferson was especially fond of the "Pani" or Pawnee corn collected from Indians encountered on Lewis and Clark's journey. Other food crops chronicled and named on the expedition include many kinds of berries, such as blue huckleberry, canyon gooseberry, golden currant and thimbleberry.