A distinctive characteristic of this genus, and also Piptochaetium and Aristida, is the very firm lemma, with elongate, hard, sharp-pointed, usually bearded callus at the base (included in measurements of lemma).
1. Body of lemma (8–) 10–13 mm long, whitish or very pale brown at maturity; glumes (17–) 22–28 mm long, including long-attenuate awned tip.
1. Body of lemma (15–) 17–23 mm long, usually dark brown at maturity; glumes (27–) 30–45 mm long, including attenuate tip.
All species found in Hesperostipa
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. April 23, 2019. https://michiganflora.net/genus.aspx?id=Hesperostipa.