General: Purple Threeawn (Aristida purpurea) is a fairly common, upright grass that grows in individual clumps (bunches) in the deserts around Las Vegas. Purple Threeawn is a spindly bunchgrass that grows from a small clump and reaches to about 18-inches tall. The flowers are held closely pressed against the stems and tend to have a purple cast. When ripe, the seeds each have three awns.

Purple Threeawn is a fairly common component of vegetation associations in the Lower Sonoran (Creosote-Bursage Flats) and Upper Sonoran (Mojave Desert Scrub and Pinyon-Juniper Woodland) life zones, especially in sandy and gravely areas.