The type specimens were collected along the Clearwater River on 8 May 1806 as the expedition traveled from Canyon Creek in Nez Perce Co. to near Little Canyon Creek in Clearwater Co., Idaho (Moulton, 1991: 226-233). No mention is made of the species in the journals. The plate is based on features found on both specimens (Rossi & Schuyler, 1993: 49) meaning that Pursh must have done sketches of the species while still in Philadelphia. (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:05/08/1806