The
Osage Plains are a
physiographic section of the larger Central Lowland province, which in turn is part of the larger
Interior Plains physiographic division. The area is sometimes called the
Lower Plains,
North Central Plains, and the
Rolling Plains. The Osage Plains, covering west-central
Missouri, the southeastern third of
Kansas, most of central
Oklahoma, and extending into north-central
Texas, is the southernmost of three
tallgrass prairie physiographic areas. It grades into
savanna and woodland to the east and south, and into shorter mixed-grass prairie to the west. The Osage Plains consist of three subregions. The Osage Plains proper occupy the northeast segment. Although sharply demarcated from the
Ozark uplift, the Plains are nonetheless a transitional area across which the boundary between prairie and woodland has shifted over time. In the central portion of the physiographic area lies the second subregion, the
Flint Hills, commonly called "
The Osage" in Oklahoma. This large remnant core of native tallgrass prairie is a rocky rolling terrain that run from north to south across Kansas and extends into Oklahoma. To the west and south of these hills are the
Blackland Prairies and
Cross Timbers. This vegetatively complex region of intermixed prairie and scrubby
juniper-
mesquite woodland extends into north-central
Texas. Bluestem prairies and oak-dominated savannas and woodlands characterize the natural vegetation in the Cross Timbers. Much of the area has been converted to agriculture, although expanses of
oak forest and woodland are still scattered throughout the eastern portion of the subregion.