Big bluegrass is a native, cool season, long-lived, perennial bunchgrass that matures early in the growing season. It is part of what is referred to as the Sandberg bluegrass complex, which includes 8 species, including big bluegrass, Canby bluegrass, slender bluegrass, Alkali bluegrass, Nevada bluegrass, Sandberg bluegrass, and pine bluegrass. The differentiating characteristics within this complex of species often vary with environmental factors, making distinguishing amongst them very difficult.