Japanese Barberry (Berberis thunbergii)

Barberry family (Berberidaceae)

Native Range   Japan

Description

Japanese barberry is a dense, deciduous, spiny shrub that grows 2 to 8 ft. high. The branches are brown, deeply grooved, somewhat zigzag 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.

Look-alikes

Japanese barberry may be confused with American barberry (Berberis canadensis), the only native species of barberry in North America, and common or European barberry (Berberis vulgaris) which is an introduced, sometimes invasive plant. American barberry is native to the southeastern United States, only occurring in the northeast as a rare introduction.

In contrast to Japanese barberry, which has smooth-edged (entire) leaves, the leaves of both American and common barberry have fringed edges. These two species also typically have two or three spines at each node in contrast to the single spine in Japanese barberry.

Ecological Threat

Japanese barberry forms dense stands in natural habitats including canopy forests, open woodlands, wetlands, pastures, and meadows and alters soil pH, nitrogen levels, and biological activity in the soil. Once established, barberry displaces native plants and reduces wildlife habitat and forage. White-tailed deer avoid browsing Japanese barberry, preferring to feed on native plants, giving the plant a competitive advantage. In New Jersey, Japanese barberry has been found to raise soil pH (for example, make it more basic) and reduce the depth of the litter layer in forests.

Distribution and Background

Japanese barberry was introduced to the U.S. and New England as an ornamental plant in 1875 in the form of seeds sent from Russia to the Arnold Arboretum in Boston, Massachusetts. In 1896, barberry shrubs grown from these seeds were planted at the New York Botanic Garden. Japanese barberry was later promoted as a substitute for common barberry (Berberis vulgaris) which was planted by settlers for hedgerows, dye and jam, and later found to be a host for the black stem grain rust. Because Japanese barberry has been cultivated for ornamental purposes for many years, a number of cultivars exist.

Japanese barberry has been reported to be invasive in twenty states and the District of Columbia. Due to its ornamental characteristics, Japanese barberry is still widely propagated and sold by nurseries for landscaping purposes in many parts of the U.S.

Japanese barberry is shade tolerant, drought resistant, and adaptable to a variety of open and wooded habitats, wetlands and disturbed areas. It prefers to grow in full sun to partial shade but will flower and fruit even in heavy shade.

Alternative Plants (Alternative native Species)

Many attractive native shrubs are available that make excellent substitutes for Japanese barberry and are readily available. Some examples for the eastern United States include:

  • Ink-berry (Ilex glabra)
  • Winterberry (Ilex verticillata)
  • Mountain laurel (Kalmia latifolia)
  • Bayberry (Myrica pensylvanica)
  • Arrowwood viburnum (Viburnum dentatum)

Whenever possible, use as alternatives plant species that are native and adapted to the ecological region where you live. They will be more valuable to the wildlife species that have evolved with them and depend upon them for food and shelter. Check with your local native plant society for recommendations and sources of native plants.

Biology and Spread

Japanese barberry spreads by seed and by vegetative expansion. Barberry produces large numbers of seeds which have a high germination rate, estimated as high as 90%. Barberry seed is transported to new locations with the help of birds (such as turkey and ruffed grouse) and small mammals which consume the fruits. Birds frequently disperse seed while perched on power lines or on trees at forest edges. Vegetative spread is through branches touching the ground that can root to form new plants and root fragments remaining in the soil that can sprout to form new plants.

Management Options

Do not plant Japanese barberry. Since it is a prolific seed-producer with a high germination rate, prevention of seed production should be a management priority. Completely remove the root portions as barberry can re-sprout from root fragments remaining in soil.

For disposal options, refer to disposal options page.

Plant Control

Manual control works well but may need to be combined with chemical in large or persistent infestations.

Biological

No biological control organisms are available for this plant.

Manual

Begin removal efforts in early spring. Pull small plants by hand when the soil is damp and loose, using thick gloves to avoid injury from the spines. Remove the entire root system. Dig up young plants with a hoe or shovel.

Removal of plants up to about 3 ft high is effective if the root system is loosened up around the primary tap root first before digging out the whole plant.

Mechanical

Use of a hoe or Weed Wrench ® is effective and may pose the least threat to non-target species and the general environment at the site. Tools like the Weed Wrench are useful when uprooting larger or older shrubs. Shrubs can be repeatedly mowed or cut. Mow and cut the plant in late summer to reduce seed production.

Chemical

Treatments using the systemic herbicides glyphosate (such as Roundup®) and triclopyr (such as Garlon) have been effective in managing Japanese barberry infestations that are too large for hand pulling.

For foliar treatments, apply a 2% solution of glyphosate mixed with water and a surfactant. Use this non-selective herbicide with care to avoid impacting non-target native plants. Apply early in the season before native vegetation has matured to minimize non-target impacts.

Application in late summer during the fruiting period may be most effective. Use triclopyr or glyphosphate on cut stumps, with a 25-30% concentration of the active ingredient. Make sure to apply the herbicide immediately after the stem is cut.

Caution: Applying herbicides to control invasive plants on property you do not personally own requires a pesticide applicator’s license issued by the state. A pesticide applicator’s license is required to use herbicides on public and private conservation lands.

Caution: Any activities in wetlands (from removing invasives by hand or by applying herbicides) may require a special permit under the Wetlands Protection Act and/or your local bylaws. Be sure to contact your local Conservation Commission before you act.

Notice: Mention Of Pesticide Products On This Web Site Does Not Constitute Endorsement Of Any Material.

 

More Information

For more information on invasive species in Massachusetts, refer to the Massachusetts Prohibited Plant List at http://www.mass.gov/agr/farmproducts/prohibitedplantlist.htm.

Author

Jill M. Swearingen, National Park Service, Center for Urban Ecology, Washington, DC.

References

Ehrenfeld, J. G. 1997. Invasion of deciduous forest preserves in the New York metropolitan region by Japanese barberry (Berberis thunbergii DC.) Journal of the Torrey Botanical Society. 124: 210-215.

Ehrenfeld, J. G. 1999. Structure and dynamics of populations of Japanese barberry (Berberis thunbergii DC.) in deciduous forests of New Jersey. Biological Invasions 1: 203-213.

Invasive Plant Atlas of New England. 2004. University of Connecticut. http://www.invasive.org/weedcd/html/ipane.htm .

Kourtev, P.S., W. Z. Huang, and J. G. Ehrenfeld. 1999. Differences in earthworm densities and nitrogen dynamics in soils under exotic and native plant species. Biological Invasions 1: 237-245.

McDonald, Brian (personal communication with Sylvan Kaufman).

Rhoads, A.F. and T. Blcok. 2002. Japanese barberry (Berberis thunbergii DC.). Morris Arboretum of the University of Pennsylvania, Philadelphia PA. 3 pp.

Shackleford, Ian (personal communication with Sylvan Kaufman).

Silander, J. A. and D. M. Klepeis. 1999. The invasion ecology of Japanese barberry (Berberis thunbergii) in the New England landscape. Biological Invasions 1: 189-201.

Swearingen, J. 2009. WeedUS Database of Plants Invading Natural Areas in the United States: Japanese Barberry (Berberis thunbergii). http://www.invasive.org/weedus/subject.html?sub=3010.

USDA, NRCS. 2009. The PLANTS Database (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Plant Conservation Alliance, Alien Plant Working Group http://www.nps.gov/plants/alien/index.htm