Central Texas is primarily characterized as a grasslands range. Grasslands are defined as areas dominated by grasses, with tree or shrub canopies covering less than 25 percent of the area. In Texas before European settlement they occupied about two-thirds of the landscape and ranged from desert and semidesert grasslands of the mountains and foothills of the Trans-Pecos to midgrass prairies of the Rolling Plains and Edwards Plateau to tallgrass or true prairies of the Blackland and Upper Coastal prairies. More than 470 native grass species live in Texas. With over 570 species, subspecies, and varieties of grasses, Texas leads the United States in numbers of grasses. The rich agricultural lands of Texas are so in large part due to the grasses that they once supported. The gentle topography and fertile soils of former grasslands today support most of the state's row crops, for most of the grasslands of the Coastal and Blackland prairies and High Plains have been converted to cropland. In fact, less than 1 percent of the original Blackland Prairie remains approximately as it once was. The fertile soils and mild climate of the Blacklands were responsible for the development of the cotton economy in Central Texas in the mid-1800s. More recent technological advances have allowed irrigation of the High Plains, and hence exploitation of the rich soils and gradual slopes of the region for cotton and small-grain production.
In general, grasslands of the Blackland Prairie and Coastal Prairie are southern extensions of the true prairie, the Rolling Plains and Edwards Plateau are southern extensions of midgrass Great Plains grassland, and the High Plains are a southern extension of the shortgrass prairie. The grasslands of Texas comprise seven geographic regions: (1) the Blackland Prairies (including the Grand, San Antonio, and Fayette), (2) the Coastal Prairie (including the Sand Plain), (3) the Rolling Plains (including the Rolling Red Prairie), (4) the Edwards Plateau, (5) the High Plains, (6) the South Texas Plains, and (7) the Trans-Pecos.