Common Name: Common Buckthorn
Scientific Name: Rhamnus cathartica
Provincial Designation: Prohibited Noxious
Prohibited Noxious weeds are plant species designated in the Alberta Weed Control Act. Prohibited noxious weeds must be destroyed when found, meaning all growing parts need to be killed or the plant's reproductive mechanisms need to be rendered non-viable.
Common buckthorn originates from Europe and was introduced to North America in the early 1800s. It has been to be used as an ornamental tree, a hedge plant, and as a shelterbelt.
Common buckthorn can spread quickly along forest edges and in abandoned fields. It can form dense stands that shade out native plants. It can also alter nitrogen levels in soils, making the habitat less suitable for native vegetation. Common buckthorn is also a host for some species of crop-damaging fungi.
Common buckthorn, also called European buckthorn, is a deciduous shrub or tree that reaches a height of up to 6 m. It has small inconspicuous yellowish-green flowers with four petals that appear in spring.
Common buckthorn has simple leaves that are elliptic to egg-shaped and are dark green in colour. The leaves have toothed edges, 5-7 prominent veins and are typically oppositely arranged. The twigs tend to come off of the branch at 90° and have a short, sharp spike at the end. A sharp stout spine is also present in many of the branch forks.
The non-edible fruits are round and black with three little seeds.
Common buckthorn is one of the last tree species to drop leaves in fall and, therefore, can be easily spotted later in the year.
Learn more about this species:
See Fact Sheet - Alberta Invasive Species Council