Members of the Lewis and Clark expedition collected plant specimens, identified plants using common names, or described in sufficient detail 108 plant species along the lower Missouri River to which modern scientific names can be assigned with different degrees of certainty. This project expands an earlier list made by Cutright of 12 plant species seen on the lower Missouri River. William Clark, the principal journalist on the lower Missouri River, described the plants in his journal entries. Meriwether Lewis collected the herbarium specimens along the lower Missouri River and made extensive, retrospective journal entries at Fort Mandan, North Dakota in the winter of 1804. The list of 108 lower Missouri River plant species is compiled from three major publications of the Lewis and Clark journals that included natural history and were edited by Elliott Coues, Reuben Thwaites, and Gary Moulton. This list is compared to a compilation by Elijah Criswell of almost 500 species of animals and plants seen over the entire exploration. The Lewis and Clark plant species list is intended to provide one of several historical lists from the 19th century to compare progress of the mitigation and restoration of lost floodplain habitat on the lower Missouri River. The plant list with the addition of modern scientific names will be an aid to the general public in interpreting the natural history of the expedition during the Lewis and Clark bicentennial commemoration from 2003–2006.