Which grasses dominate the North American prairie?

The North American prairie is dominated by various species of grasses, with the specific composition determined largely by regional rainfall levels. These grasslands are categorized into three primary subtypes:1

• Tallgrass Prairie: Found in the more humid eastern regions, this area is dominated by sod-forming grasses such as big bluestem and prairie cordgrass (or slough grass) in wet lowlands, alongside bunchgrasses like needlegrass (porcupine grass) and prairie dropseed on drier upland sites.1
• Midgrass (Mixed-grass) Prairie: Occupying the central prairie region, this is the most extensive subtype. It is characterized by a mix of bunchgrasses and sod-forming grasses, including porcupine grass, grama grass, wheatgrass, and buffalo grass.1
• Shortgrass Plains: Located in the driest western parts of the prairie, the vegetation is primarily composed of buffalo grass and grama grass.1

Additionally, Kentucky bluegrass is found across all three major prairie subtypes, though it is not a native species. While these grasses historically defined the landscape, much of the native cover has been replaced by agricultural cultivation or grazing.12