Common Buckthorn

Common buckthorn

(Rhamnus cathartica)


This plant is shade and drought tolerant with the ability to grow in a multitude of different soil qualities. All of these factors led it to be extremely prolific throughout Ontario. There are few predators to buckthorn, however, birds have been known to graze the berries in later winter due to lack of another food source. Due to the buckthorn berries being a laxative and lower in nutrition than native berries this proves to be an issue as birds are getting less nutritional value and are losing fluids due to the laxative effect
Buckthorn holds its leaves late into the fall, so if you see a shrub with full foliage, it may be this invasive. Max height is 6 meters but the average is 2-3 meters high. The branches host green leaves which split off from the stem in pairs, like a mirror image or the leaves alternate along the branch. At the end of the branches, you can sometimes find thorns and very often find blackberries throughout the shrub.


Common in most of southern Ontario, It is also found in Manitoba, Quebec, Saskatchewan and Nova Scotia

Control & Impacts

Due to its abundance, it is extremely hard to control, it is recommended that landowners fo an annual removal of the fruiting shrubs in order to control spread. If you cut the shrub, the stum will regrow, so it is advised that you remove the stump of treat it with herbicides.

It is host to the soybean aphis and oat crown rust fungus. The soybean aphid is also a promoter to the Asian lady beetle as the aphid is the beetle’s main food source. So common buckthorn-soybean aphid-lady beetle are all intertwined.
-Grows out a thick canopy that does not allow much undergrowth, crowding out indigenous plants.
-Fast germinating seeds make it outcompete many other indigenous species.

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