Common Buckthorn originates from Europe. It was introduced to North America in the 1800’s as an ornamental garden shrub. It has spread throughout Eastern and Central North America. There are extensive populations of Common Buckthorn in Western PEI and some isolated patches in the Central region.
Positively identifying Common Buckthorn can be difficult because the closely related Glossy Buckthorn is widespread and looks very similar. Both trees grow to be around 20ft at maturity. However, there are a few features that can be used to differentiate between the two:
Common Buckthorn has slightly-toothed leaf edges. Glossy Buckthorn’s leaves have smooth edges.
Common Buckthorn has a spike at the end of branches. The spike is absent in Glossy Buckthorn.
Green-yellow flowers grow in close bundles and bloom mid-spring through to early summer.
Flowers form green berries, which ripen to black in late Summer.
Berries remain all winter.
What it does in the ecosystem
Common Buckthorn tolerates a wide range of upland habitats including forests and riparian zones. Common Buckthorn outcompetes native species through a variety of mechanisms. It forms a dense canopy layer that readily shades out surrounding species, and it secretes a chemical from its roots that is poisonous to other plants. Common Buckthorn is not as widespread on PEI as its close relative Glossy Buckthorn.