Berberis thunbergii, or Japanese Barberry, has been reported as an invasive plant in 20 U.S. states and the District of Columbia. The National Park Service has requested that Japanese Barberry not be planted. It is a highly adaptable and resistant plant that has been found to displace native plants, reduce wildlife habitat, raise soil pH, and reduce the depth of forest litter layers.
Japanese Barberry was introduced to America in 1875 and has become a common substitute for American Barberry and European Barberry. Japanese Barberry is a deciduous shrub that grows up to 6 feet tall. It is dense and thorny with deeply grooved brown branches and foliage that changes from bright green in summer to orange, scarlet, and reddish purple in autumn.
The flowers of the Japanese Barberry are yellow and bloom from mid-spring to early summer. It also sports glossy bright red ovoid berries. Each berry contains a single seed. The germination rate of the Japanese Barberry has been estimated at 90 percent, and its spread is aided by birds and small mammals that eat its seeds and berries.
Barberries are popular hedge plants for many reasons: they have a uniform growth rate; they transplant easily and prune well; they are disease- and insect-resistant; and they tolerate dry, urban environments better than most shrubs. However, many native shrubs can be used as non-invasive substitutes for Japanese Barberry. These include bayberry (Myrica pensylvanica), inkberry (Ilex glabra), winterberry (Ilex verticillata), arrowwood (Viburnum dentatum), mountain laurel (Kalmia latifolia), ninebark (Physocarpus opulifolius), and hearts-a-bustin' (Euonymus americana).