Common Buckthorn (RWMWD Plant Guide)

Common Buckthorn

Rhamnus cathartica

Summary ³

Rhamnus cathartica, the buckthorn, common buckthorn or purging buckthorn, is a species of small tree in the flowering plant family Rhamnaceae. It is native to Europe, northwest Africa and western Asia, from the central British Isles south to Morocco, and east to Kyrgyzstan. It was introduced to North America as an ornamental shrub in the early 19th century or perhaps before, and is now naturalized in the northern half of the continent, and is classified as an invasive plant in several US states and in Ontario, Canada.

Description ⁴

Family:
Rhamnaceae (Buckthorn)

Height:
Up to 25 feet at maturity

Habit:
Small, single-stemmed tree or multiple-stemmed shrub; Tree DBH typically between 4-8”, but can grow up to 15”; Shrub DBH up to 6”, typically less; Fast-growing

Leaves:
Glossy, deep green leaves (up to 2½” long and 1½” wide) are egg-shaped, with subtly pointed tips, margins with rounded teeth, and 3-4 lateral veins per side that curve sharply towards the leaf tip.

Bark:
Young bark is dull gray and smooth with scattered lenticels, and often appears to have faint, darker gray horizontal stripes. Older bark is very dark gray-brown to nearly black, typically very peely, and somewhat warty in appearance.

Flower:
Flowers grow in bunched clusters (up to 1½” across) of up to 10 flowers. Individual flowers (up to ¼” across) are yellow-green in color, with 4 nearly triangular, spreading sepals and inconspicuous petals.

Fruit:
Berry-like fruit (up to ¼” across) hangs in small clusters near branch intersections. Fruit begins green in color, maturing to a shiny blue-black color with purple flesh inside.

Bloom time:
June-July

Fall color:
Leaves remain green throughout the fall, typically turning orangey-brown in color long after other species have lost their leaves. Some withered leaves may persist on the branches throughout the winter.

Nicknames:
Buckthorn

Habitat:
Common Buckthorn will grow under most conditions in nearly any soil type, but does best in conditions ranging from light shade to full sun, and in soils that are moist to very well-drained. It is commonly found in woodland understories, thickets, fencerows, urban plantings, waste areas, and in a variety of other sites, especially those with disturbed soils.

Wildlife Benefits:
Fruit is a food source for birds, who in turn spread its seeds across the landscape. Flowers are attractive to some bees and flies. Winter host plant for Soybean Aphids (Aphis glycines), a common agricultural pest of growing concern.

Notes:
This species is highly invasive, and can be managed by hand pulling or herbicide treatment. Contact your local watershed district, soil and water conservation district, or the DNR for more information about invasive buckthorn control and removal.
While birds enjoy this species’ fruits, they have a powerful natural laxative effect on humans and should not be consumed.

Identification Tips:
Notable characteristics that aid in the identification of Common Buckthorn (Rhamnus cathartica) include dull grey, smooth bark on young trees, which may appear to have darker gray, horizontal striping and/or faint, scattered lenticels. Older trees have very dark brown to nearly black, often peely bark, which may also appear warty. Its buds are nearly opposite and dark brown in color, with a thorn-like spike protruding from the tip of the twig between the two buds. When branches are scraped or cut, the cambium is a distinct orange color that is not seen in other species. Finally, this species generally hangs onto its leaves far later into the season than its native neighbors, with orange-brown, shriveled leaves often persisting through the winter.

Common Buckthorn can be very similar in appearance to the native Black Cherry (Prunus serotina), especially when young; however, a young Black Cherry tree typically has lighter colored, shinier, more reddish to purplish-brown bark, distinct lenticels, and alternate, reddish brown buds. Common Buckthorn, on the other hand, typically has grayer bark and nearly opposite, darker colored buds. Further, when the branches of Black Cherry are scraped or cut, the cambium will appear green, instead of Buckthorn’s distinct orange color.

Black Cherry is also susceptible to black knot fungus (Apiosporina morbosa), which manifests as bumpy, black galls that surround portions of the tree branches, further helping to distinguish these species, especially when they grow in close proximity to one another.

References:
https://www.minnesotawildflowers.info/tree/common-buckthorn
https://www.illinoiswildflowers.info/trees/plants/cm_buckthorn.htm
https://plants.ces.ncsu.edu/plants/rhamnus-cathartica/
https://www.mortonarb.org/trees-plants/tree-plant-descriptions/common-buckthorn-illegal-sell-illinois
https://www.fs.fed.us/database/feis/plants/shrub/rhaspp/all.html

Range ⁴

Sources and Credits

(c) JanetandPhil, some rights reserved (CC BY-NC-ND), http://www.flickr.com/photos/30979614@N07/3943672583
Adapted by Ramsey-Washington Metro Watershed District from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Rhamnus_cathartica
(c) Ramsey-Washington Metro Watershed District, some rights reserved (CC BY-SA)

More Info

iNat Map

Family	Rhamnaceae
Habit	Shrub, Tree
Life cycle	perennial
Origin	introduced
Listing	invasive, noxious weed, prohibited or restricted
Bloom time	(6) June, (7) July
*sites	Lake Phalen, Snail Lake

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