This cosmopolitan liverwort species was described by Linnaeus long before the Lewis and Clark expedition, and the Lewis and Clark specimen was never a potential type specimen. It is of course still among the earliest collected specimens of this species from western North America. Research Associate Christine Manville has noted that in amongst the liverwort material is a fragment of an unidentified moss. This specimen was collected at Travelers' Rest (Missoula Co., Montana) on the day during which Lewis and Clark made preparations to separate (a party under Clark's command went to retrieve matériel left at Camp Fortunate [Beaverhead Co., Montana] in August 1805, while Lewis traveled with volunteers more directly to the Falls of the Missouri, where the parties rejoined). This day (1 Jul 1806) Lewis made numerous natural history observations in his journal, including a lengthy description of the prairie dog. (The Lewis & Clark Herbarium Digital Imagery Study Set, ANSP, 2002) On deposit at the Academy of Natural Sciences, Philadelphia Collected by:Meriwether Lewis & William Clark Collection date:07/01/1806