Common & Glossy Buckthorn
Common (Rhamnus cathartica) and Glossy Buckthorn (Frangula alnus) are two of Ontario's most unwanted invasive plants. These non-native buckthorns invade a variety of habitats, with glossy buckthorn often invading wetlands. Common buckthorn serves as a host for the fungus that is responsible for oat crown rust. As farmers know, this fungus can reduce oat and barley yields.
- Buckthorns usually grow 2 to 3 m tall.
- Leaves are finely toothed and are arranged opposite in pairs on a common buckthorn; glossy
buckthorn leaves are alternate and have smooth edges.
- Common buckthorn typically have a thorn at the end of each branch, which distinguishes them from other buckthorns.
- Flowers are small and a light green color.
- In late summer, buckthorns produce many clusters of black berry fruits.
- Common buckthorn is found along roadsides, riverbanks, mature forests and farm fields; glossy buckthorn is often found in wetlands.
Where is Buckthorn found in our watershed?
Common buckthorn is fairly common in the NVCA watershed with particularly strong infestations in and around Collingwood. Glossy buckthorn is less common but is invading our northern wetlands in Oro-Medonte and Springwater townships.
Why is it of concern?
Both invasive buckthorns can grow in a variety of conditions and have the ability to form dense bushes that crowd and shade out native species.
Dense growth in an area can cause a change in the soil’s nitrogen level so that it better suits growth of the buckthorn.
Its fruit produces a large amount of seeds and can germinate quickly, causing population sizes to increase rapidly. Birds enjoy the fruit and disperse it widely via their droppings.
How to Control the Spread
Ideally buckthorn shrubs should be manually pulled from the ground within its first couple of years of establishment.
Pulling is easiest when soils are wet and it is recommended it take place in mid-October to cause minimal disturbance on other species nearby.
It is necessary that the entire root be removed since the buckthorn can re-sprout and cause even larger populations.
Cutting back the bush stem is another option, as long as a legal herbicide can be used to prevent re-sprouting from occurring.
Remember to clean your shoes after hiking and keep pets on a leash to avoid further spread.
Use native or non-invasive species when gardening on your property.
Early Detection is Key
Early detection and rapid response is essential for the control and/or eradication of invasive species in an area. If you find one of the invasive species listed above, please report the sighting to
Invasive Species on Private Property
NVCA does not offer a service to remove invasive species on private property. If you are looking for tips on dealing with invasive species on your property, see the links above, or visit
Ontario's Invading Species Awareness Program.
Thank you to the Ontario Invasive Species Council and the Ontario Invasive Species Awareness Program for the photo.