Meehan (1898: 18) lists the specimen under Cerastium arvense but suggest Pursh's C. elongatum might be a good species. The taxonomy of this highly variable, circumboreal species is still not thoroughly resolved. Jalas (1964: 140) recognizes numerous subspecies in Europe and PH-LC 50 keys to subsp. arvense. The specimen was collected on 22 Apr 1806 near the mouth of the John Day River, possibly in Klickitat Co., Washington. It is not known if Lewis found the plant on the Washington or Oregon side of the river, but the party camped on the Washington side that night (Moulton, 1991: 155-159). (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:04/22/1806