Aristida genus grasses (with the exception of A. longifolia) have C4 metabolism ( Cerros-Tlatilpa and Columbus 2009) With a few exceptions they are
Flower spikelets with one floret, glumes narrow, membranous, tip pointed to short-awned; lemma hard (indurate), linear tipped by 3 elongate awns, rolled inward around the palea and grain. Awns initially parallel, becoming divergent at maturity or when dry.
Fruit dry, 1-seeded, lemma remains closely wrapped around the palea and grain, breaking off the inflorescence above the glumes, which remain on the dry plant.
Habitat; our usually in dry, open sites.