Sagebrush typically dominate drier , non @-@ forested areas at lower elevations . Species that commonly occur with sagebrush include Sandberg bluegrass , wild onion , milk vetches , bluebunch wheatgrass , bitterbrush , gray horsebrush , green rabbitbrush , and others . In riparian areas below 5 @,@ 500 feet ( 1 @,@ 700 m ) , trees such as black cottonwood , narrowleaf cottonwood , thinleaf alder , water birch , and mountain maple grow with shrubs including chokeberry and willows . Riparian areas in largely treeless habitats such as sagebrush steppe primarily consist of willows along with thinleaf alder , chokecherry , mountain maple , shrubby cinquefoil , fireweed , saxifrage , and grasses .