For the purpose of vegetation classification, the Intermountain region has been variously defined as comprising a number of phytogeographic units (Cronquist et al., 1972). Of these, the Bonneville basin forms the largest floristic section in the Intermountain region (Holmgren, 1972). The Bonneville basin floristic section includes mountain ranges peripheral to the lake bed and covers 38,500 mi2 of land surface. At its highest level, Lake Bonneville covered 19,940 mi2 and was the largest of the Pleistocene lakes in the Great Basin. Even today, ...