Grassland areas in the United States begin in the Midwest with the tallgrass prairie and progress to shorter grass types, as the observer travels west. The change from tall to short grass corresponds with a decline in annual rainfall and is often accompanied by a gradual increase in elevation.
The perennial plants of the tallgrass prairie often exceed four feet in height and form a nutrient-rich sod, which includes a dense mat of rhizomes and underground stems. Drier parts of the North American prairie are characterized by shorter bunch grasses that do not have connecting root systems.
Wildflowers that grow among the prairie grasses most commonly belong to the aster or pea family of plants, which includes sunflowers, asters, daisies, and clover. Also present in a temperate grassland are small islands of trees.
The animals of the temperate grasslands are usually limited in diversity but still very abundant. In North America the pronghorn and bison are two major grazers while at ground level more animals such as mice, gophers, badgers, coyotes, ferrets, and prairie dogs can be found.
