Achnatherum richardsonii is a species of grass known by the common names Richardson's needlegrass, spreading needlegrass, and Canada mountain-ricegrass. It is native to northwestern North America, where it is distributed from Alaska and Yukon through the western Canadian provinces south to Colorado. This is a tufted perennial bunchgrass growing up to a meter tall. The inflorescence is open with spreading branches. The spikelet has a twisted awn up to 2.5 centimeters in length.