Of the plants collected by Lewis and Clark, 94 were new to science.

In 1802, President Thomas Jefferson began organizing America’s first official government-sponsored exploration of the regions west of St. Louis overland to the Pacific. Jefferson, himself an amateur scientist, was particularly interested in the practical applications of newly discovered plants, proclaiming botany to be “among the most useful of the sciences.” When he appealed to Congress for financing, however, Jefferson emphasized the journey’s diplomatic goals and potential trade benefits, being well aware that scientific discovery would not be a priority with the politicians.

The Corps of Discovery

Jefferson put his personal secretary, Meriwether Lewis, in charge of the expedition. Lewis invited his old army friend William Clark to serve with him as co-leader of Jefferson’s newly formed Corps of Discovery. In addition to extending America’s fur trade and furthering geographic and ethnographic knowledge, the expedition was charged with expanding scientific intelligence of the geology, animals and plants encountered along the way. Before Lewis embarked on the journey, Jefferson arranged a science “crash course” for his protege, including tutoring from professor and botanist Dr. Benjamin Smith Barton.


The Osage Orange Tree

Meriwether Lewis began cataloging plants even before the expedition officially began. On March 26, 1804, he recorded information about his first encounter with an Osage orange tree (Maclura pomifera) in the garden of his St. Louis host. He prepared cuttings to send to Jefferson with a detailed description of the tree, beginning, “I send you herewith inclosed, some slips of the Osages Plum, and Apple...” Within a few decades, the Osage orange would become one of the most popularly planted trees on the farms of American settlers.

Garden Flower Discoveries

Other seeds and cuttings collected on the journey were nurtured and tested by Jefferson and nurserymen like Bernard McMahon (1775-1816). McMahon, the author of the influential 1806 The American Gardener’s Calendar and publisher of America’s first seed catalogue, acted as curator of the plants amassed by the expedition. Production and marketing of Lewis and Clark’s plants was soon underway. In addition to the large number of trees, shrubs and food crops (particularly berries) they documented, we can thank Lewis and Clark for discovering some flowers popular in American gardens to this day.



On August 4, 1804, Lewis first encountered snow-on-the-mountain (Euphorbia marginata) near Fort Atkinson in Nebraska. He describes “[a] beatifull plant with a variagated leaf these leaves incompass the flowers which are small and in the center of them; at a small distance they resemble somewhat a white rose...” This large and showy white-flowered annual is a member of the spurge family.


Prairie Coneflower

In the winter of 1804, while at Fort Mandan, North Dakota, Lewis records information about the prairie coneflower (Echinacea angustifolia), noting that it is used by native Americans as “an excellent poltice for swellings or soar throat.” A native of dry prairies, this plant--also called black samson or narrow-leaved purple coneflower--is right at home in naturalistic gardens.



On May 29, 1806, near Kamiah, Idaho, Captain Clark writes, “Capt. L-s met with a singular plant in blume of which we preserved a specimen.” He was describing clarkia (Clarkia pulchella), a Pacific Northwest wildflower eventually named in his honor. Also known as pinkfairies, ragged robin or deerhorn clarkia, this showy annual features bright pink to lavender flowers and was a popular offering of American seed catalogs in the mid-1800s.


Western Jacob’s Ladder

Western Jacob's ladder (Polemonium pulcherrimum), a perennial mountain wildflower, was discovered along Lolo Trail in Idaho on June 27, 1806. Similar to the Eurasian variety of Jacob’s Ladder, this plant has bell-shaped light purplish-blue flowers and interesting foliage resembling the steps of a ladder.


Common Monkey Flower

The monkey flower (Mimulus guttatus) was discovered on the Blackfoot River in Montana on July 4, 1806. Its large yellow snapdragon-like flowers often have a red tinge at the throat. Both annual and perennial forms are available.


Perennial Blanket Flower

The brightly-colored blanket flower (Gaillardia aristata) is as much admired today as it was 200 years ago. Although Lewis and Clark’s specimen label notes only that it was collected “on dry hills on the Rocky-mountains” on July 7, 1806, it was most likely found by Lewis as he was navigating the Lewis and Clark Pass in Montana. Blooming from summer through fall, the drought-tolerant daisy-like blossoms look like red and yellow pinwheels.


Lewis’ Prairie Flax

Collected near Sun River, Montana, on July 9, 1806, prairie flax (Linum perenne lewisii) was first sold in an American seed catalog in 1811, and is still popular today. This delicate perennial blooms early in the season and is beloved for its clear blue flowers.

National Park Service: The Science of the Lewis and Clark Expedition
Monticello Twinleaf Journal: "Public Treasures": Thomas Jefferson and the Garden Plants of Lewis and Clark
National Geographic: Lewis and Clark
Smithsonian Museum of Natural History: Lewis and Clark as Naturalists

Photo credits
: Images of Lewis and Clark in the public domain; Dave's Garden photos: Osage Orange by chicochi3; Euphorbia by Jeff_Beck; Coneflower by buddeyallen; Clarkia by kennedyh; Jacob's Ladder by Grasmussen; Monkey Flower by eje; Blanket Flower by Joy; Prairie Flax by sweezel