1. Involucre a spiny bur enclosing much or all of the spikelets, the whole readily disarticulating.
1. Involucre of slender bristles ca. 2–4 cm long subtending but not concealing the spikelet.
All species found in Cenchrus
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. March 28, 2017. http://michiganflora.net/genus.aspx?id=Cenchrus.