Pursh provides an extended description of the species, noting it was found "On dry hills on the Rocky-mountains." On the label, Pursh gives this and a date. The morning of 7 Jul 1806 found Lewis's party on Beaver Creek in Lewis and Clark Co., Montana. They set out early heading northeast crossing the Continental Divide via Lewis and Clark Pass to an evening camp near Table Mountain (Moulton, 1993: 95-96). Most of the country east of the divide is low in elevation and characterized by "dry hills." The species is common here even today. Clark's party, on the other hand, was delayed in leaving camp having lost nine horses overnight. They were in Big Hole Valley in Beaverhead Co., Montana. After considerable delay, the main portion of Clark's men moved onward across Big Hole Pass, where they camped after going some 25 miles (Moulton, 1993: 169-171). Neither explorer mentions collecting this beautiful plant. Coues (1898: 305-306) suggests Lewis gathered the type, and given the circumstances, this seems most reasonable. Cutright (1969: 409) gives the date of the collection as 6 Jul. (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:07/07/1806