The Lewis and Clark specimen, which we regard here as a paratype, was collected along the Missouri River below the mouth of Cannon Ball River in Sioux Co., North Dakota, on 17 Oct 1804 (Moulton, 1987a: 471). Moulton notes that Lewis has two different numbers for this species, but both "48" and "103" are found on the one label at PH, and when Lewis's specimens were received by the American Philosophical Society on 16 Nov 1805, only the one sheet is reported (Moulton, 1987a: 464). It is possible that Pursh had a duplicate of the Lewis and Clark specimen with him in London, and this accounts for the Lewis and Clark reference written by Lambert on the back of the sheet. Most likely this fragment was discarded, as happen with other items, when a better sheet (in this case the Nuttall specimen) was obtained. (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:10/17/1804