[26] Calamagrostis purpurascens is a large, clump forming, perennial grass; growing 30–80 cm (12–31 in) tall.

[27] It grows from short rhizomes and has dense, often purpled tinted flower heads that are 4 to 13 cm (1.6 to 5.1 in) long.

[28] 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).

[28] In Minnesota it is an endangered species found growing in the north eastern part of the state in the coniferous region in Cook county where it is found on tall north facing cliffs composed of slate and diabase; these locations are cool, moist, and lack heavy competition from other plant species.

[28][29] Carterocephalus palaemon (arctic skipper) butterflies eat the nectar from C. purpurascens flowers, and their caterpillars feed on the shoots.