Muhlenbergia microsperma is a species of grass known by the common name littleseed muhly. An annual or short-lived perennial tufted grass with a purplish inflorescence, it is native to the Americas from the Southwestern United States through Central America to northern South America. It is usually found in many habitats, particularly open areas, cliffs and slopes, and disturbed sites. It is characterized by the presence of closed, self-pollinating flowers on its lower stems and small spikelets.