Purple Threeawn

Aristida purpurea



Purple Threeawn is a slender, densely tufted bunchgrass that grows up to 20 inches or 50 cm in height. Its sheaths cover up to one-half the internode. It has mostly basal leaves up to 10 inches or 25 cm long but only 2 mm wide that roll inward. The seed head is narrow with few branches, nodding, loose and purplish, with many three-awned spikelets. The second glume is twice as long as the first. The awns, the most striking characteristic, are widely spreading, nearly equal in length, and 1-2 inches or 3-6 cm long. The lemmas are purple-tinged. It has also been called "needlegrass." You can distinguish Aristida purpurea from other Aristida species by its long hairs at the leaf collar. It is a variable species with at least five varieties in Texas.    Poor grazing for both livestock and wildlife. It is grazed only in the spring when plants are green and leaves are young. The long awns can irritate livestock and contaminate wool. It is a great grass for erosion control and regeneration, having a fibrous root system, drought tolerance, and high seed production. 


This perennial, warm-season, native grows on rocky hills and sandy plains while sometimes occurring on clay soils; it increases on overgrazed ranges. It’s a colonizer species that likes the sun often growing with Sandy Dropseed (Sporobolus virginicus) and various grama species (Bouteloua spp.).