Achnatherum nelsonii is a species of grass known by the common names Columbia needlegrass, subalpine needlegrass, and western needlegrass. It is native to western North America, from Yukon and British Columbia to California to Texas. This perennial grass grows in leafy clumps up to 175 centimeters tall. The inflorescence is a narrow panicle with branches upright or pressed parallel to the stem. The roots may extend nearly one meter deep into the soil. The grass remains green throughout much of the season, sometimes until the first snowfall.