 These species grow in the driest parts of North America's grasslands and usually consist of a single plant layer made up mostly of shallow-rooted bunch grasses that grow between 12 and 18 inches (30 to 46 cm) high.Some plant species indigenous to the area include western wheatgrass ("Pascopyrum smithii"), snowberry ("Symphoricarpos"), and silver sage.Animal species that can be found in the area include