Aristida purpurascens is a species of grass known by the common name arrowfeather threeawn.

[1] This perennial bunchgrass produces stems up to 100 centimeters tall.

The leaf blades are hairless, pale green, and up to 25 centimeters in length.

[2] The panicle-shaped inflorescence has branches appressed to the stem, making it narrow.

[1] This plant may be grazed when young but as it ages it becomes low in quality and even dangerous for livestock because of the sharp spikelets.