1. Leaves compound, evergreen; stem without spines (but leaflets spiny-toothed); ripe fruits dark blue.
2. Leaves smooth beneath.
2. Leaves papillose beneath (most easily seen along larger veins where papillae can be viewed from the side).
1. Leaves simple, deciduous; stem spiny at nodes; ripe fruits red.
3. Leaves entire (at most with an apiculus or small terminal spine); flowers solitary or in small clusters.
3. Leaves with spiny-toothed margins; flowers in a raceme.
All species found in Berberis
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. May 25, 2017. http://michiganflora.net/genus.aspx?id=Berberis.