Aristida purpurea--Purple Threeawn stands roughly fourteen to thirty-one inches in height. Purple Threeawn has three awns stemming from a densely tufted seedhead that measures 1 1/2 to 1 3/4 inches long.  The seedhead and the awns are purple to maroon just prior full maturation and this is where the purple comes from in the common name "Purple Threeawn".   It grows well in either sandy or clayey soils.