New Mentzelias (Loasaceae) from the Intermountain Region of Western United States

Abstract Three new species and two new varieties of Mentzelia belonging to the multistemmed subshrub group of section Bartonia are described. Typical of the group, they are narrow endemics occurring in relatively barren clay soils in the Intermountain Region of interior western U.S. Mentzelia tiehmii and Mentzelia argillicola are from Nevada, Mentzelia memorabalis from northern Arizona, Mentzelia multicaulis variety uintahensis from northeastern Utah and northwestern Colorado, and Mentzelia multicaulis variety flumensevera from central Utah. Communicating Editor: Aaron Liston