Rhamnaceae

1. Leaf blades with 3 prominent veins from the base; flowers white, in dense inflorescences at the ends of branches or on axillary peduncles; fruit dry, dehiscent.

Ceanothus

1. Leaf blades clearly pinnately veined, not strongly 3-nerved from the base; flowers yellow-green, solitary or numerous but all axillary; fruit fleshy, indehiscent.

2. Leaves entire (sometimes slightly undulate but at most irregularly crenulate); flowers all bisexual; sepals 5; petals 5; bud scales (actually the reduced leaves of naked buds) pubescent.

Frangula

2. Leaves with close, small, often crenulate teeth; flowers unisexual or bisexual (plants dioecious or polygamo-dioecious); sepals and petals 4, or sepals 5 and petals 0; bud scales glabrous except for the ciliate margins.

Rhamnus

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. November 29, 2014. http://www.michiganflora.net/family.aspx?id=RHAMNACEAE.