Japanese barberry is a perennial deciduous shrub species that originates in Europe and was introduced to North America in 1875. It naturalized by the early 1900's. It is now found in several eastern Canadian provinces (QE, ON, NS, NB) and in many eastern and mid-western US states (USDA 2011). It is also reported from British Columbia.
Japanese barberry is a spiny 0.3 to 3 m shrub with simple dull smooth leaves, with flowers solitary or in an umbel of up to 5 flowers, and red berries (Flora North America 2011). Leaves are small, entire, often spatula-shaped and green, bluish-green, often reddish in coloration; branches are brown and zig-zag.with a single spine at each node (Plant Conservation Alliance Alien Plant Working Group 2011). Roots are shallow. Japanese barberry is considered an invasive species. However it is still propagated and sold in nurseries. It can form dense stands, altering ecosystems and habitats (soil pH changes and leaf litter reduction), and is shade tolerant and drought resistant (Plant Conservation Alliance Alien Plant Working Group 2011). Reproduction is both sexual (seeds dispersed by birds) and asexual (it is clonal); it can sprout from root fragments (Conservation Alliance Alien Plant Working Group 2011).
This species flowers from late March to May over its range.
Synonyms and Alternate Names:
Berberis thunbergii var. atropurpurea Chenault
This spiny shrub may be mistaken in BC for common barberry (Berberis vulgaris). Several key features separate the two, however. The leaves on Japanese barberry are entire and untoothed, while the leaves on common barberry are coarsely spine-toothed; the flowers of Japanese barberry are solitary flowers or umbellate with up to 5 flowers while the flowers of common barberry are racemose. with 10-20 flowers per raceme (Flora North America 2011).