Japanese barberry | skymeadows

Japanese barberry (Berberis thunbergii)

COMMON NAMES:
barberry
Japanese barberry
Thunberg's barberry
red barberry

SCIENTIFIC SYNONYMS:
Berberis thunbergii DC. var. atropurpurea Chenault

CONFIRMATION STATUS: Confirmed.

TAXONOMY: The currently accepted scientific name for Japanese
barberry is Berberis thunbergii DC. 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. Berberis ×
ottawensis is a hybrid of Japanese barberry and common barberry (Ber-
beris vulgaris). Japanese barberry is also used to breed hybrids for horti-
cultural purposes.

NATIVE STATUS: Introduced, United States and Canada.

GENERAL BOTANICAL CHARACTERISTICS: Japanese barberry
is a deciduous shrub, usually about 3 to 6 feet (1-2 m) tall but ranging from
about 1 to 10 feet (0.3-3 m) tall. Shrubs have multiple stems originating
from the root crown, plus shoots arising from rhizomes at variable distances
from the root crown. Individual shrubs are typically dense and compact and
usually broader than tall at maturity, with widths of 3 to 8 feet (1-2.5 m).
Stems may be erect to decumbent, and have short axillary shoots and
dense, spreading branches. One authority also refers to shoots arising from
stolons. Aerial stems have simple, short, stiff spines and dense foliage.
Leaves are simple and entire, typically about 0.2 to 1 inch (0.5-2.5 cm)
long and 3 to 18 mm wide, with short petioles, 0 to 8 mm. Flowers are 8
to 15 mm wide and solitary or borne in small, umbellate clusters of 2 to 5
flowers along the entire length of the stem. Fruits are bright red berries
with dry flesh, about 7 to 11 mm long. Japanese barberry has a large,
shallow root system with rhizomes and many fine roots radiating from a
root crown. Sprouts occur from rhizomes at variable distances from the
root base and form diffuse swarms of stems.

REGENERATION PROCESS: 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 (e.g., turkey and ruffed
grouse) and small mammals which eat it. Birds frequently disperse seed
while perched on powerlines 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.

Japanese barberry populations range from small plants occurring at low
densities to dense stands with up to 40 stems/individual, and few plants
growing under the crown area. Japanese barberry stems arise not only
from seeds, but also sprout from the root crown, sprout from rhizomes,
and arise from the rooting of long stems that touch the ground at variable
distances from the root base. These many forms of reproduction can result
in diffuse swarms of stems covering a large area, making it difficult to

determine the limits of an individual plant.

The combination of multiple forms of population growth and low mortality
rates allows Japanese barberry to produce dense, persistent populations.
The invasive potential of the more than 40 cultivars of Japanese barberry
is not well known.

SITE CHARACTERISTICS: In parts of North America where invasive
populations of Japanese barberry occur, characteristics that influence its
distribution at landscape and site scales include climate and microclimate,
current and past land use, and soil characteristics. In general, Japanese bar-
berry seems to prefer mesic conditions, and invasive populations often
occur near homesites, roads, and trails. Japanese barberry can occur in
relatively undisturbed forest, and invasive populations are often described
in second-growth forests that were formerly cleared for agriculture or tim-
ber harvest, especially former pastures. While Japanese barberry often
occurs on soils with higher pH and available nitrate than uninvaded sites,
these soil characteristics likely resulted from Japanese barberry invasion,
rather than the reverse.

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 part shade but will flower and fruit even in heavy shade.

Japanese barberry prefers well-drained soils, although it has been found in
wet, calcareous situations, (specifically in a black ash swamp). It is typically
found in locations of partial sunlight such as a woodland's edge; it can sur-
vive well under the shade of an oak canopy. It is also found along roadsides,
fences, old fields, and open woods.

SUCCESSIONAL STATUS: Japanese barberry is shade tolerant
and may establish and persist in any successional stage. Examples from
the available literature suggest that it probably establishes best on open,
disturbed forest sites in early succession and usually persists as forest
succession proceeds. However, some accounts indicate that Japanese
barberry does not always persist or persists only in open areas in some
communities as succession proceeds. Substantial evidence indicates that
Japanese barberry establishment is not restricted to open sites, and that
establishment and persistence in late-successional environments is
common.

Japanese barberry is a widely planted ornamental that has spread not only
into open fields and forest edges adjacent to human development, but also
into closed-canopy forest. Dense Japanese barberry stands may have few
understory plants growing under the crown area.

SEASONAL DEVELOPMENT: Flowering occurs from mid-April to
May in the northeastern United States. Fruits mature during late summer
and fall and persist through the winter.

GENERAL DISTRIBUTION: Japanese barberry is not native to
North America, but was introduced in the 1800s. Japanese barberry distri-
bution in North America is from Quebec and Ontario in Canada, south to
Georgia and Tennessee, and westward to the eastern edge of North and
South Dakota, Nebraska, and Kansas. In the United States it is most abun-
dant throughout the Northeast with the exception of northern Maine and
northern Vermont. Japanese barberry is less common where it occurs west
of the Mississippi River and south of North Carolina. At the western ex-
treme of its distribution, it is reported from Crook County in Wyoming.

Japanese barberry is a popular ornamental and landscape plant. Local
florae indicate that Japanese barberry is commonly planted and escapes
cultivation in the northeastern United States and adjacent Canada including
Ontario, Nova Scotia, Michigan, Illinois, Ohio, and West Virginia; and the
Blue Ridge Mountain counties in North Carolina, South Carolina, and
Virginia.

Japanese barberry is native to Japan; Japanese barberry was documented
in the United States by 1818. Other accounts indicate that Japanese bar-
berry seeds were received at the Arnold Arboretum in Boston around
1875 and from there were distributed for cultivation in the United States.
Japanese barberry was promoted as a substitute for common barberry,
which was introduced to North America by early settlers from Europe for
hedgerows, dyes, and jams, and later found to be a host for black stem rust
(Puccinia graminis) of wheat and consequently eradicated. Most Japanese
barberry cultivars are resistant to infection by black stem rust and are
therefore approved for cultivation in the United States by the USDA,
Agricultural Research Service. Fewer cultivars are approved by Agricul-
ture Canada for cultivation in Canada. However, Japanese barberry is
considered invasive in many areas, although some cultivars may be less
invasive than others.

SKY MEADOWS DISTRIBUTION:

Shrub specimens can be found on trails marked in red.

       Bleak House
       Appalachian Trail/Old Trail
       South Ridge/North Ridge
       Gap Run
       Snowden
       Woodpecker Lane

       Sherman's Mill
       Rolling Meadows/ Lost Mountain
     Fish Pond

The specific distribution of Japanese barberry has not been determined.

HABITAT TYPES AND PLANT COMMUNITIES: Japanese bar-
berry is most problematic in mature forest communities in the eastern
United States, where it often forms dense thickets. It occurs in upland
and riparian settings, wetlands, pastures, and meadows. It occurs more
frequently and is more abundant in post agricultural forests than in less
disturbed, continuously wooded sites.

IMPORTANCE AND USES: Information on use of Japanese barberry
by livestock and wildlife is limited and comes primarily from reviews.

One account suggests that it is "little browsed by livestock" although some
authorities include Japanese barberry in the group of nonnative plant spe-
cies that provide "some value as wildlife food and cover". Some researchers
have found that Japanese barberry is "highly preferred by mule deer".
However, other reviews suggest that white-tailed deer dislike Japanese
barberry and selectively browse on associated native species. Gardening
experts claim Japanese barberry has become a favored landscaping plant
because of the unpalatability of its foliage to deer. However, research sug-
gests that dense populations of white-tailed deer in the Northeast may be
agents of long-distance dispersal of Japanese barberry fruits, because
hoofed browsers, especially white-tailed deer, eat barberries (Berberis
spp.) "freely" and are known to disperse fruits of other Berberis species
in western North America.

The bright-colored fruits of Japanese barberry are available to birds
throughout winter in the eastern United States, although some birds may
eat them only when other foods are scarce or absent. However, wild turkey
and grouse utilize Japanese barberry fruit heavily, and recent increases in
wild turkey populations may contribute to Japanese barberry spread. A
study in central New Jersey documented Japanese barberry seed in the
feces and stomachs of several native frugivorous birds.

Japanese barberry is a popular ornamental due to its ease of culture and
general attractiveness. Many other species in the barberry family are
also used as ornamentals, though some, such as the nonnative common
barberry (Berberis vulgaris), are shunned because they are alternate
hosts to black stem rust of wheat. Common barberry is no longer a com-
mon plant in North America, since control efforts in the early 1900s
practically eradicated it.

A close relative of Japanese barberry, common barberry, was historically
used as a substitute for the popular medicinal plant, goldenseal (Hydrastis
canadensis). Roots of both plants are rich in several alkaloids, including
berberine. A study comparing alkaloid content and antibacterial activity
of Japanese barberry with those of common barberry and goldenseal
revealed that alcohol extracts of all 3 plants exhibit activity against bac-
teria associated with sore throats (Streptococcus pyogenes) and oppor-
tunistic skin infections (Staphylococcus aureus). This supports the trad-
itional uses of these plants for wound healing and for soothing minor mouth
and throat irritations. The results suggest that with respect to its berberine
content and in vitro antibacterial activity, Japanese barberry is a potential
substitute for goldenseal, which is classified as threatened or endangered in
many of its natural habitats due to overharvesting and loss of habitat. Com-
mercial applications of these findings, with regard to Japanese barberry,
are being explored.