common buckthorn Rhamnaceae Rhamnus cathartica

Leaf:Opposite or sub-opposite (partially alternate), simple, elliptical to nearly oval, 2 to 3 inches long, finely serrated, dark shiny green above, much lighter below.
Flower:Species is dioecious; small, yellow-green, 4 petals, in small clusters, appearing in spring.
Fruit:Round, 1/4 inch in diameter, drupe, shiny black when ripe in late summer.
Twig:Slender stiff, reddish brown, later with exfoliating gray layer, many end in a sharp thorn; buds, scaly, ovate, pointed, 1/4 inch, reddish brown to dark brown, appressed.
Bark:Smooth, shiny gray to reddish brown with numerous lenticels, later becoming dark gray and scaly; large specimens become rectangular blocky; inner bark is yellow.
Form:A large, suckering shrub or small low branching tree up to 25 feet tall.

Notes: