The lectotype was collected near Kamiah in Idaho Co., Idaho, on 5 Jun 1806. Lewis mentions observing "several of the pea blume flowering plants" this day (Moulton, 1991: 335), one of which may have been this species. The paratype is annotated with the species name and a date, 7 Jul 1806. On this date, Lewis traveled from Beaver Creek in Lewis and Clark Co., up the Blackfoot, and over the Continental Divide via Lewis and Clark Pass into Cascade Co (Moulton, 1993: 95-96). We suspect he found the plant along the Blackfoot River west of the Pass where it occurs today. Pursh's protologue includes the comment "Flowers pale purple, or rose-coloured." The label on PH-LC 137 has "Flowers cream coloured with a small tinge of blue." As this is a conflict, it is possible the lectotype designated by Fleak and Dunn is not the element Pursh had before him when he proposed the name. Likewise, Pursh gives the location for the new species as "On the banks of the Kooskoosky . . . July" which is confusing as Lewis was on the Clearwater River in June and on the Blackfoot in July (see Lupinus argenteus, No 113 above). The late David Dunn prepared a slide of a flower from the lectotype and application of the name has been based upon this sheet. We suspect that at one time there was much more plant material associated with the paratype, and it was upon this specimen now at K that Pursh based the name in 1813. Fortunately, the specimens at K and PH-LC are the same species. (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:06/05/1806