This is one of the plants that Isabel Mulford collected from the Boise foothills during her time in Idaho in 1892, hosted by Mary Hallock Foote.  She decided it represented a new species and described it as Oenothera idahoensis.  Subsequent researchers have decided that our plants are actually the same as O. caespitosa ssp. marginata, which was first collected in 1837 from near present-day Twin Falls, by a member of a fur-trading expedition.