Canada’s annual Invasive Species Awareness Week aims to start a conversation with citizens and organizations about cracking down on non-native plants and animals.
Introduced by gardeners in the 1880s, and then widely used for windbreaks and erosion control, buckthorn has spread aggressively. It has invaded roadsides, riverbanks, mature forests, and farm fields, forming dense stands and reducing biodiversity.
Its abundant fruit make it easy for the fast-germinating seeds to be widely disseminated, in the droppings of birds and other animals.
The fruits have an even sneakier trick to ensure spread: They act as a laxative, causing wildlife to quickly deliver the seeds into the environment.
How to identify common buckthorn
- Buckthorn is usually the first shrub to leaf out in the spring and the last to drop its leaves late in the fall.
- It often grows 2 to 3 meters tall. Occasionally it reaches 6 meters, with a trunk up to 25 centimeters in diameter.
- It is distinguished by the sharp, thorn-tipped branches in contrast to the simple or compound thorns growing from the sides of branches in the Hawthorns.
- It has smooth, dark green leaves that are finely toothed, 2.5 to 6 centimeters long, with prominent forward-curved side veins, arranged in opposing pairs along the stem.
- It produces clusters of purplish-black berries along the stems and short twigs, and each berry usually has 4 hard seeds.