Calamagrostis purpurascens, variously known by the common names purple reedgrass, purple pinegrass, or alpine reedgrass is a perennial grass, growing 30 to 70 centimetres (28 in) tall. Calamagrostis purpurascens is native from arctic Greenland, to much of Canada (Alberta, British Columbia, Manitoba, Newfoundland, Northwest Territories, Nunavut, Ontario, Quebec, Saskatchewan, and Yukon Territory) and the western and northern U. S. (Alaska, California, Colorado, Idaho, Minnesota, Montana, Nevada, New Mexico, Oregon, South Dakota, Utah, Washington, and Wyoming). It is rare and scattered in the southern U. S. states, such as Louisiana, where it is a post-glacial relict. Further south, C. purpurascens is also known in Chile, where it was recorded by Rodolfo Amando Philippi in 1860. Philippi gave it the name Deyeuxia robusta, now relegated to synonymy. It is also found in Asia (in eastern Siberia). Habitat. C. purpurascens grows in dry mountainous zones, from high up on the foothills to close to the snow-line, often taking root in gaps in the talus, where few other plants can grow. Ecology. Carterocephalus palaemon (arctic skipper) butterflies eat the nectar from C. purpurascens flowers, and their caterpillars feed on the shoots. Ovis canadensis (bighorn sheep) are known to graze this grass.