Pursh provides a full description in Latin. He implies by his distribution statement he had two collections before him, one from "the prairies of the Rocky-mountains" and a second from along "the Columbia river." Only the former sheet now exists. Lewis collected the type in Nevada Valley, Powell Co., Montana, on 6 Jul 1806, at what Lewis called "the prarie of the knobs" (Moulton, 1993: 93). The Pursh plate was based on the above lectotype (Rossi & Schuyler, 1993: 49). Three years almost to the day after Pursh published his book on the flora of North America, Pierre Antoine Poiret formally published the genus Purshia to honor the author, Frederick Traugott Pursh (1774-1820; originally Friedrich Traugott Pursch). The new generic name was suggested initially by Augustin Pyramus de Candolle. This widespread shrub is common throughout much of western North America and bears equally the common names of antelope bitterbrush, bitterbrush or purshia. For more information on Pursh, see Gray's (1882) commentary on him and other early botanists in America. (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:07/06/1806