Meehan (1898: 42) and Cutright (1969: 415) report the specimen as Populus trichocarpa Torr. & A. Gray ex Hook. (Icon. Pl. 9: ad t. 878. 1852), the more commonly used scientific name for black cottonwood (see Little in U.S.D.A. Agric. Handb. 541: 208. 1979). The Lewis and Clark specimen was gathered along "the Columbia River" in Jun 1806. The species was commonly observed along the Columbia River in April and May of that year (Moulton, 1991). However, the expedition was not along the Columbia in June. On 2 Jul, Lewis remarks that the "leaf of the cottonwood on this river [Bitterroot] is like that common to the Columbia narrower than that common to the lower part of the Missouri and Mississippi and wider than that on the upper part of the Missouri" (Moulton, 1993: 79). The expedition was at Travelers' Rest in Missoula Co., Montana. Given the developmental stage of the specimen, PH-LC 175 was probably gathered in Montana rather than Washington. (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