1. Lemmas with a stout, strongly twisted awn and often with stiff hairs on the back; florets falling from the spikelet by a distinct oval disarticulation surface.
1. Lemmas with the awn usually straight, weak, or absent, and the back glabrous; florets falling by fracture of rachilla at base of spikelet.
All species found in Avena
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. August 17, 2017. http://michiganflora.net/genus.aspx?id=Avena.