Nassella viridula is a species of grass known by the common name green needlegrass. It is native to North America, where it is widespread in western Canada and the western and central United States. It is introduced in parts of eastern North America. This grass is found in many types of habitat, including disturbed areas where it acts as a pioneer species. It is also considered a climax species in some regions, such as North Dakota. It is a dominant species and an indicator species in a variety of habitat types. It tolerates a wide range of temperatures and it is drought-tolerant.