This specimen has been identified as D. meadia by Meehan (1898) and Cutright (1969), and more recently as D. jeffreyi by Moulton.  However, more than 100 years after the Corps of Discovery passed the Dalles on their return trip, L.F. Henderson recollected this species at the same site as did Meriwether Lewis, finally recognizing and publishing it as a new species.  Reveal et al. (1999) state, "It is somewhat remarkable that this plant, first found in 1806, went undiscovered for over a century."