A foreign invader; it makes a fine hedge, but it is beginning to show up where it is not wanted. The tiny flowers probably go unnoticed most of the time, but they make a very pretty display close up. The long thorns and spoon-shaped leaves are distinctive. This one was blooming at the beginning of May on a wooded hillside in Mount Lebanon.

The National Park Service (in a “least wanted” posting) gives us this description:

Japanese barberry is a dense, deciduous, spiny shrub that grows 2 to 8 ft. high. The branches are brown, deeply grooved, somewhat zig-zag in form and bear a single very sharp spine at each node. The leaves are small (½ to 1 ½ inches long), oval to spatula-shaped, green, bluish-green, or dark reddish purple. Flowering occurs from mid-April to May in the northeastern U.S. Pale yellow flowers about ¼ in (0.6 cm) across hang in umbrella-shaped clusters of 2-4 flowers each along the length of the stem. The fruits are bright red berries about 1/3 in (1 cm) long that are borne on narrow stalks. They mature during late summer and fall and persist through the winter.