Leymus cinereus is a species of wild rye known by the common names basin wild rye and giant wild rye. It is a common native grass of western North America, including western Canada and the United States from California to South Dakota and Minnesota. It grows in many types of habitat, including grassland and prairie, forests, scrub, chaparral, and sagebrush. This is a perennial grass forming large, tough clumps up to 2 meters tall and sometimes exceeding one meter in diameter. It has a large, fibrous root system and sometimes small rhizomes. The flower cluster is an unbranched, cylindrical spike divided into up to 35 nodes with several flower spikelets per node.