Basin wildrye is robust, densely bunched, perennial grass. The wildrye clumps are to 1 m wide. It has up to 200 cm deep rhizomes. Flower stems are 70 to 200 cm tall. Stems are glabrous or hairy. Leaves are 4 to 20 mm wide. Flower spike is 10 to 30 cm long, with 16 to 35 nodes. Every node has 2 to 7 spikelet, 9 to 19 mm long. It blossoms from June to August. Basin wildrye can grow on dry places in valleys, dust-holes or among sagebrush at the edge of forests. It ranges from British Columbia and Saskatchewan to California, northern Arizona, central Colorado, and the Black Hill area; also in Minnesota; in Montana the Rosebud County only.
Cheyenne women spread wildrye under beds of willow sticks (Grinnell 1923 I: 242). This plant served as a bedding during various ceremonies, e. g. the Sweat Lodge or Sun Dance ceremony. It is said the wildrye bedding cooled people standing upon it. It helped to the Sun Dancers who spent many hours in the summer sun. If Cheyennes wanted to obtain stable black dye they tied wildrye in bunches and burned. Then they mixed the ash with blood until the mixture get dark color (Grinnell 1923 II: 19).