Pursh's hand-written label indicates the specimen was collected on the "High dry prairies" on "Septb: 12. 1804." According to Moulton (1987a: 67-68), on 12 Sep 1804 the expedition was along the Missouri River of Charles Mix and Brule cos., South Dakota. Cutright (1969: 88) interprets the date on the specimen as 13 Sep. Moulton (in press) suggests this specimen was collected in 1806 and that Pursh mistakenly wrote 1804. The rationale for this is that the sheet is not accounted for in Lewis's list of plants gathered that year (Moulton, 1987a: 450-472). On 12 Sep 1806, the expedition was rapidly moving down the Missouri River. Their morning camp was mostly likely in Andrew Co., Missouri; their evening camp was at St. Michael's Prairie in Buchanan Co., Missouri (Moulton, 1993: 355-356). Liatris aspera was collected on 12 Sep 1804 (see No. 101 above), but was duly recorded in Lewis's list. The species is a common member of the Great Plains flora and the var. humilis is known to occur in Charles Mix and Brule cos., South Dakota (Great Plains Flora Association, 1977). Steyermark (Fl. Missouri: 1496, 1497. 1963), however, does not report the species from either Andrew or Buchanan cos. although it is found nearby. The var. humilis does occur in Missouri (Heard & Semple, 1988), albeit rarely, and then not along the Missouri River. The correct name of the taxon is probably Oligoneuron rigidum var. humilis (Porter) G. L. Nesom (in Phytologia 75: 27. 1993). Nesom (1993) defines Oligoneuron as a genus of six species. (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