1. First glume 0.3–0.7 mm wide on a side (midrib to margin), about half as wide as second glume; back of upper lemmas scabrous, at least toward tip; anthers (0.5–) 0.7–1.5 mm long.
1. First glume less than 0.3 mm wide on a side, much less than half as wide as second glume; back of upper lemmas smooth (midnerve often slightly scabrous); anthers not over 0.5 (–0.8) mm long.
2. Second (larger) glume not swollen or distended, ± obtuse to acute at apex.
2. Second (larger) glume distinctly swollen or distended, abruptly truncate and usually shallowly 2-lobed at apex.
All species found in Sphenopholis
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. July 23, 2019. https://www.michiganflora.net/genus.aspx?id=Sphenopholis.