Because of the Snake River's geographical isolation there are a number of plants that have evolved in Hells Canyon that grow nowhere else on earth. Though some species are more widespread, the specific varieties of the species are not.
List of plants endemic to Hells Canyon
Arabis crucisetosa Constance and Rollins
Boechera hastatula Greene
Astragalus arthurii M.E.Jones
Astragalus vallaris M.E.Jones
Calochortus macrocarpus var. maculosus (A.Nels. & J.F.Macbr.) A.Nels. & J.F.Macbr.