Purple three-awn.

Description

Aristida purpurea is a species of grass native to North America which is known by the common name purple three-awn. This grass is fairly widespread and can be found across the western two thirds of the United States, much of southern Canada and parts of northern Mexico. It is most abundant on the plains. This is a perennial bunchgrass, growing erect to under a meter-3 feet in height, and the flower glumes often assumes a light brown to reddish-purple color. There are several varieties with overlapping geographical ranges. This is not considered to be a good graze for livestock because the awns are sharp and the protein content of the grass is low. Aristida is a very nearly cosmopolitan genus of plants in the grass family.Aristida is distinguished by having three awns (bristles) on each lemma of each floret. The genus includes about 300 species found worldwide, often in arid warm regions. This genus is among those colloquially called three-awns wiregrasses, speargrasses and needlegrasses. The name Aristida is derived from the Latin "arista", meaning "awn". They are characteristic of semiarid grassland. The Wiregrass Region of North America is named for A. stricta. Other locales where this genus is an important component of the ecosystem include the Carolina Bays, the sandhills of the Carolinas, and elsewhere, Mulga scrub in Australia, and the xeric grasslands around Lake Turkana in Africa. Local increases in the abundance of wiregrasses is a good indicator of overgrazing, as livestock avoid them. Aristida stems are ascending to erect, with both basal and cauline leaves. The leaves may be flat or inrolled, and the basal leaves may be tufted. The inflorescences may be either panicle-like or raceme-like, with spiky branches. The glumes of a spikelet are narrow lanceolate, usually without any awns, while the lemmas are hard, three-veined, and have the three awns near the tip. The awns may be quite long; in A. purpurea var. longiseta they may be up to 10 cm.