A guide to nonnative invasive plants inventoried in the north by ...

Appendix E
Key to the species Berberis
1. Leaves evergreen...Berberis julianae
1. Leaves deciduous...2
2. Leaf margins spinulose-toothed; leaves 1.5-9 cm; twigs gray;
thorns often with 2 side branches as long as the center spine;
flowers racemose...Berberis vulgaris
2. Leaf margins smooth; leaves 1-4 cm; twigs brown; thorns
often solitary, or with 2 small side branches; flowers in small
clusters or solitary...Berberis thunbergii