Arizona cottontop is a native, perennial, long-lived, warm-season bunchgrass. It has slender, erect stems which are from 12 to 40 inches (30-100 cm) tall. The leaves are normally 3 to 5 inches (8-13 cm) long, but may be up to 10 inches (25 cm) in length. They are 0.125 to 0.25 inches (2-6 mm) broad. The inflorescence is a narrow, densely flowered panicle, usually 3 to 4.75 inches (8-12 cm) long. Spikelets are normally borne in pairs on the rachis. The cottony seedhead is covered with long silky hairs, and the seeds are about 0.07 inches (1.7 mm) long. Arizona cottontop's root system is finely divided and branched. It is concentrated mostly in the upper 8 inches (20 cm) of soil, but in coarse-textured soils it extend down to about 40 inches (100 cm).