Populus deltoides Bartr. ex Marsh. ssp. monilifera (Ait.) Eckenw. Plains cottonwood The expedition needed trees on numerous occasions as sources of lumber, firewood, and shade. In spite of Lewis low esteem for its qualities, the cottonwood was often the only timber at hand to fulfill their lumber requirements, including building the winter quarters at Fort Mandan and constructing canoes. More than once, in the barren landscape of the high plains, the Lewis and Clark expedition would welcome a small grove of cottonwoods to protect them from sun or rain during a respite or an overnight stay, and to provide firewood for cooking or warmth. Cottonwoods require moist soils, and their natural habitat, along the edges of streams and rivers on islands above the flood plain, made them easily accessible for the Corps. Populus balsamifera L. ssp. trichocarpa (Torr. & Gray ex Hook.) Brayshaw black cottonwood - Susan McDougall @ USDA-NRCS PLANTS Database In an early comment, Lewis found the cottonwood so abundant as to be troublesome to the traveler. Not a bad-looking tree, Lewis compared it to the beautiful and celebrated Lombardy poplar, but he saw it as useless
except for some of the pirogues the Indians made with the trunks of the larger trees (Lewis journal, May 25, 1804). His main complaint was that the wood was not durable; indeed Sgt Gass described it as a light soft wood (Gass journal, November 28, 1804). Nevertheless, cottonwoods happened to be a crucial resource in several instances. The plains cottonwood provided the lumber for the construction of the party s winter lodge at Fort Mandan. Eight huts, each 14 feet square, were built on the east bank of the Missouri taking advantage of the availability and size of the trees. Overall, as Sgt Ordway wrote, we find the cottonwood Timber will Split Tollorable well, and as their is no other building timber in this bottom we expect to Split punchin to cover the huts with (Ordway journal, November 2nd, 1805). This was done a few weeks later, according to Sgt Gass s journal (November 28, 1804). Canoes from Clark s journal February 1st, 1806 Reproduced in Thwaites 1959 vol.4 Photo Smithsonian Institution Before leaving Fort Mandan in May 1805, and probably following the Indian method, Lewis had his men hollow out large cottonwood trunks to make six sturdy canoes. Though the journals say nothing about the sort they built, later
in the trip Lewis and Clark sketched several of the fine canoes they saw with Indians from the Pacific coast. To his own surprise, Lewis found that the horses he had bought from Indians would prefer the bark of the cottonwood to the meals he had prepared for them. He realized that, in the winter, the Mandans would cut down trees and fed their horses with the tender branches and cut pieces of the scrapped bark (Lewis journal, February 12, 1805; Cutright 1969:86). A few months later, the larger size of some of the local cottonwoods helped them portage around the Great Falls. At Fort Mandan they had used trees 18 inches in diameter (Gass journal, November 28, 1805). At the Great Falls, Sgt. Gass was in charge of the construction of two wagons to transport the heavy dugout canoes and all the expedition equipment around the falls. He found a tree 22 inches in diameter, big enough that the men could cut cross sections to serve as wheels (Lewis journal, June 17, 1806). Cottonwoods are less abundant today, although big trees survive thanks to a root system able to seek water as deep as 30-40 feet below ground (Cutright 1969:139). The Missouri River course has changed during the last 200 years and dramatically reduced the habitat for these large trees of the prairie. Interest in navigable waters has deepened and narrowed the channel in many places, eliminating the shallow riverbeds where the trees used to grow. Likewise, several dams have been built across the Missouri River to control flooding and to provide electricity. These dams created large lakes in the place of the meandering river and, consequently, the cottonwood habitat has disappeared.
Two other types of cottonwoods Although the Plains cottonwood was already known to science, Lewis reported and collected two other types previously unknown: Populus angustifolia James, narrow-leaved cottonwood, and Populus balsamifera ssp. trichocarpa, black cottonwood. Populus angustifolia in Nuttall s Sylva Photo Smithsonian Institution They differ from the plains cottonwood by the shape of their leaves and their location along the trail. The party found the narrow-leaved cottonwood near Great Falls. All three cottonwood species are found in Montana and Wyoming, but the plains cottonwood is not found beyond lower elevations of the eastern slope of the Rockies and their foothills, while the narrow-leaved cottonwood, the dominant species in the Rocky Mountains, does not extend beyond the western slopes of the Rockies and Bitterroots, leaving the black cottonwood as the predominant species along the Columbia River and its tributaries (Earle and Reveal 2003:206-207). On July 26, 1806, Lewis found the three species growing together along the Two Medicine River, in modern Montana (Reveal and al. 1999: n. 152).
Bibliography Cutright, Paul Russell. 1969. Lewis and Clark: Pioneering Naturalists. University of Nebraska Press, Lincoln and London. For cottonwoods, see pp. 86, 107, 123, 131, 139, and 159. Earle, Scott A. and Revea, James L. 2003. Lewis and Clark s Green World, The Expedition and its Plants. Farcountry Press, Helena, MT. Nuttall, Thomas. 1849. The North American Sylva. Smith & Wistar, Philadalphia. 3 volumes. Reveal, James L., Moulton, Gary E., Schuyler, Alfred E. 1999. The Lewis and Clark collection of vascular plants: Names, Types, and comments. Proceedings of the Academy of Natural Sciences of Philadelphia 149: 1-64, 29 January 1999 Thwaites, Reuben Gold. 1959. Original Journals of Lewis and Clark expedition 1804-1806. Antiquarian Press LTD, New-York (First Published 1904-1905). Volume 4. Internet Resources Fact sheet page on cottonwoods, Great Plains Nature Center website - http://www.gpnc.org/cottonwood.htm United States Department of Agriculture (USDA) Plant Database, http://plants.usda.gov/index.html The text of the University of Nebraska edition of the Lewis and Clark journals edited by Gary Moulton [The Definitive Journals of Lewis and Clark - By Meriwether Lewis and William Clark, set of 13 volumes, 2002 ] is available at The Journals of the Lewis and Clark Expedition Online Edition - http://lewisandclarkjournals.unl.edu/ Dominique Harre Rogers Edited by Rusty Russell