In his written orders to Meriwether Lewis and William Clark, President Thomas Jefferson referred to observing and collecting plants. He wrote, "Other object worthy of notice will be the soil & face of the country, it's growth & vegetable productions; especially those not of the U.S."
When writing this short sentence, Jefferson probably didn't realize the important role plants would play, both in the survival of the expedition and the eventual development of the West.The skills of the two captains could not have been better matched. Clark was a surveyor and cartographer. Lewis was a naturalist. Records show that Clark collected only one plant during the entire expedition, a white-margined spurge he found along the Yellowstone River in July 1806, when the two men were separated on the return trip. Otherwise, Lewis observed, collected, described and preserved all of the specimens.
Lewis began studying botany at an early age. His mother was an herbalist in Albemarle County, Virginia, and she taught him the medicinal properties of plants. He used this knowledge to treat party members and natives for various maladies during the expedition. Lewis continued his studies when he became Jefferson's private secretary in 1801. Jefferson, one of the best naturalists in the country at that time, passed along his knowledge of botanical classification and nomenclature. To prepare for the expedition, Jefferson sent Lewis to Philadelphia for six weeks to study botany, navigation and medicine with members of the American Philosophical Society.
Equipped with wilderness skills, practical knowledge and numerous reference books, Lewis and Clark prepared for the two-year mission. They collected their first plant before they even left Camp Dubois, near present-day St. Louis. It was an Osage-orange. They sent a cutting to Jefferson from St. Louis on March 26, 1804. This Osage-orange was the first of 178 plants collected during the expedition that were new to science.
Of the 178 plants they discovered, 140 were from west of the Continental Divide. They likely described more eastern species, but the expedition's collections from Fort Mandan to the Great Falls of the Missouri were destroyed by floods during the winter of 1805-06.
The plants found by Lewis and Clark were curiosities, but they were also necessary to their survival. Trees along the river provided fuel, shelter and wood for new masts, oars and dugouts. Near the present town of Waverly, Missouri, the party camped for two days to make 20 new boat oars from ash trees growing near the river.
Cottonwood was probably the most common tree they saw along the Missouri River. After collecting a packet of cottonwood seeds near La Charette, Lewis wrote, "this specimine is the seed of the Cottonwood which is so abundant in this country . . . this tree arrives at a great size, grows extreemly quick the wood is of a white colour, soft spungey and light, perogues are most usually made of these trees…"
Despite its "soft spungey" wood, expedition members used cottonwood to make dugouts and masts. They even built Ft. Mandan--their 1804 winter home--from cottonwood cut along the river.
In addition to building materials, plants provided food for the members of the Corps of Discovery. Many of the explorers were sick before they even made it across present-day Missouri. Clark speculated their illnesses were caused by the water they drank. Actually, the cause was what they were eating, or not eating. Their high-protein meat diet lacked fruits and vegetables. As the summer progressed, the men anticipated the ripening of wild fruits and nuts. Plums, pawpaws, cherries, grapes, raspberries, persimmons, walnuts and hickory nuts found along the river gave them a more varied diet.
Lewis's detailed journal entries on the plants he collected included the date and place he found them, descriptions of the plants and if the native people used them for food or medicinal purposes. Common lomatium was, for example, "A great horse medicine among the natives."
Of the mariposa lily, Lewis wrote, "A small bulb of a pleasant flavor, eaten by the natives." He was less impressed with sticky currant, saying, "fruit indifferent and gummy."
The group probably wished they had avoided certain plants, particularly camas. After nearly starving as they crossed the Lolo Trail, the men gorged themselves on dried salmon and camas roots supplied by the Nez Perce. Clark's journal reads, "I find myself verry unwell all the evening from eateing the fish & roots too freely." The next day was not much better, judging from this entry: "Capt Lewis Scercely able to ride a jentle horse... Several men So unwell that they were Compelled to lie on the Side of the road for Some time..."
Even under life-threatening circumstances, the pair relentlessly recorded new findings. They collected about one-third of the new plants, 55, in Idaho when they were struggling to cross the snow-covered Lolo Trail.
During the long winter at Fort Clatsop, Lewis and Clark caught up on their map making and journal entries. Lewis wrote at length about edible plants and the great conifers of the region, such as Douglas-fir, western hemlock, grand fir, western white pine and Sitka spruce. He reported the Sitka spruce "grows to imence size…in several instances we have found them as much as 36 feet in the girth or 12 feet diameter perfectly solid and entire, they frequently rise to the hight of 230 feet, and one hundred and twenty or 30 of that hight without a limb."
The local Indians' diet included the edible roots of many plants, including thistle, horsetail, western bracken, cattail and wappato. Lewis said they most favored the roots of wappato plant. The wappato bulb is about the size of an egg and, according to reports, when roasted tastes much like a potato. Native women gathered it from swampy places where it grew. They waded into water sometimes up to their necks and loosened the bulbs with their feet. When the bulbs floated to the surface, they tossed them into their canoes.
Douglas-fir, purple coneflower, Lewis's wild flax, Pacific yew, camas and cottonwood are just a few of the plants recorded during their mission that we use today for food, fiber, medicine and shelter.
The discoveries made by the Lewis and Clark Expedition greatly increased our knowledge of western botany and helped encourage development of the West. Many of the plants they discovered and described were new species, and a few became members of new genera, Lewisia and Clarkia.
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