bittersweet

American/Oriental Bittersweet Celastrus scandens and C. orbiculatus
Family: Celastraceae (Stafftree)
Branching: Alternate

These two species of vine are quite similar in the winter, and are mainly distinguished by where the fruits grow out of the stem (American Bittersweet has fruits on the terminal ends of the branches only, while Oriental Bittersweet has fruits growing out of twig axils as well). Both bear the distinctive "arils" characteristic of the family (most often seen with the Euonymous genus), and these apparently can also be helpful in identification (the outer casing of American is orange and the outer casing of Oriental is yellow). The buds of both species are small and stubby, but sharply pointed at almost 90 degrees to the main stem.

The fruits of Oriental Bittersweet. They are arils, which have an interior "berry" inside a shell that splits.

Clusters of arils. They are not as distinctive once the outer shell falls away.
Notice how the fruits are growing out of the axils. This indicates Oriental Bittersweet;
American Bittersweet fruits grow only out of the terminal ends of the branches.

Lateral bud, at an almost 90 degree angle to the main stem.

Lateral bud and leaf scar of Oriental Bittersweet

Lateral bud and leaf scar of American Bittersweet
(I'm not sure if the differences are consistent enough to be diagnostic)

Mature bark of American Bittersweet