Common Name: Glossy buckthorn, alder buckthorn
Scientific name: Frangula alnus, syn. Rhamnus frangula
Identification: Glossy buckthorn is an upright, spreading shrub or small tree that grows up to 23’ tall. It is often multi-stemmed. Though members of the species are usually close in width and height, certain cultivated varieties are narrow and columnar in shape. Young twigs are green but turn grey-brown with age and do not bear spines. Mature bark is dark brown with distinct white pores called lenticels. The oval leaves are arranged alternately on the twigs and are 1 ½ – 3” long and half as wide with smooth edges. Leaves are green and glossy on top, pale green below, and have prominent veins. Certain cultivars have narrow almost fern-like leaves. Flowers are ¼” in diameter and have five white petal-like sepals and five very small white petals between the sepals. Glossy buckthorn blooms from mid-spring through mid-summer. Fruits are ¼” in diameter and grow in clusters of 1 – 3. They ripen from green to yellow to red to black at maturity in late summer. Fruits contain 2 – 3 seeds each. (Dirr 2008, Hilty)
Look-alikes: Glossy buckthorn can be differentiated from invasive common buckthorn (Rhamnus cathartica) and most native buckthorns (Rhamnus spp.) by its untoothed leaves. Glossy buckthorn is very similar in appearance to the U.S. native Carolina buckthorn (F. caroliniana). However, Carolina buckthorn’s range is more southern in the Midwest and it is not found in the Great Lakes region. The leaves of Carolina buckthorn are larger – often up to 5” in length – and its flower stems are hairy, while the flower stems of glossy buckthorns are hairless (Hilty).
Glossy buckthorn is reported frequently throughout the Great Lakes region with the largest number of reports coming from northern Wisconsin and the Upper Peninsula of Michigan. On a continental scale, glossy buckthorn is most commonly reported in the Great Lakes region and in New England. USDA reports glossy buckthorn as being hardy to a minimum temperature of -38oF (Zone 3a), contributing to its wide distribution in the upper Midwest.
Additional invasive species distribution data for specific Great Lakes jurisdictions are available via:
- Midwest Invasive Species Information Network (Michigan)
- iMapInvasives (New York and Pennsylvania)
- EDDMapS Ontario
Glossy buckthorn is distributed over long distances by birds and wildlife which eat the fruit. Seed can also be spread by surface water when the species occurs in riparian and wetland habitat.
Glossy buckthorn is tolerant of saturated soils and prefers full sun exposure but can tolerate shade. It is often found invading moist woodlands, swamps, fens, streambanks, and wetland edges. However, it has also been known to grow in upland habitats including open woods, forest edges, old fields, ditches and rights of way.
Glossy buckthorn has characteristics that enable it to quickly establish large single-species stands. Once established, it produces large amounts of seed, contributing to thicket-like growth which prevents the growth of native plants. It also out-competes other species by leafing out very early in the spring and losing its leaves late in the fall, effectively extending its growing season.
Glossy buckthorn was introduced in the late 1800’s as an ornamental plant. Similar to common buckthorn, it was often used for wildlife habitat plantings, hedges, and windbreaks. A handful of cultivars with feathery leaves and a narrow crown shape are still available in trade though trade in this species (including all cultivars) is prohibited in many jurisdictions.
There is some controversy over the status of certain cultivars of glossy buckthorn – most notably ‘Asplenifolia,’‘Columnaris,’and a cultivar bred from the two called ‘Fine Line.’ Field trials have demonstrated that Fine Line produces significantly less seed than the straight species, and that its seeds germinate less readily under the same conditions (Deppe 2010). However, others in the industry have observed Fine Line spreading in a garden setting (Bachtell 2019 pers. comm.). It is not clear whether Fine Line breeds true (i.e., whether its seedlings would also be less seedy than the species), and whether the reduced rate of seeding and germination is sufficient to make it non-invasive. Population modeling indicates that for long-lived trees and shrubs, even relatively low fruiting individuals can contribute to invasive population growth (Knight et al. 2011). Of the six Great Lakes jurisdictions that regulate this species, only one has exempted the Fine Line cultivar.
Please see our Landscape Alternatives pages for more information about how the WIGL Collaborative selected alternatives.
|Alternatives for Glossy Buckthorn
Common name (Latin name)
|Tall shrub or small tree;
good for screening
|Narrow & upright form
(like ‘Fine Line’ buckthorn)
|American hornbeam (Carpinus caroliniana)||✔||✔||✔|
|American hazelnut (Corylus americana)||✔||✔|
|Northern spicebush (Lindera benzoin)||✔||✔|
|Alder-leaved buckthorn (Rhamnus alnifolia)||✔||✔|
|American arborvitae (Thuja occidentalis)||✔||✔||✔||✔|
|Arrowwood viburnum (Viburnum dentatum)||✔||✔|
|Blackhaw viburnum (Viburnum prunifolium)||✔||✔|
|Carolina allspice (Calycanthus floridus)||✔|
|Vernal witchhazel (Hamamelis vernalis)||✔||✔|
|Boxwood (Buxus sp.)
|Sweetshrub hybrid (Calycanthus x)
|Blood-twig dogwood (Cornus sanguinea)
‘Cato’ ARCTIC SUN™, ‘Winter Flame’
|Anglo-Japanese yew (Taxus x. media)
~ = trait is somewhat present but not as pronounced as in check-marked examples
a ‘Green Mountain’ is a tall boxwood cultivar and may eventually grow to 7’, though it is slow-growing
b Anglo-Japanese yew is sold as dioecious (male or female) clones, and only the females will produce fruit. The recommended cultivar is female. However, many nurseries only sell unsexed plants.
Green = native to part of the Great Lakes Basin
Yellow = native to the United States but not to the Basin
Blue = not native but not invasive
The WIGL Collaborative’s decision trees are designed to help site users, who are perhaps newly discovering that plants that are part of their home landscaping are invasive, prioritize which species should be removed first based on risk to the surrounding environment, economy, and occasionally, to human health. In a perfect world, everybody would remove all invasive plants from their landscaping right away, but in reality, removing mature woody plants involve a hefty investment of time and/or money. These diagrams can help people with multiple woody invasives in their landscaping prioritize to get the most benefit for their efforts.
To learn more about the methodology and information used to develop the decision trees and for helpful hints on how to answer the questions, please see the full report here (PDF).
The following is a brief overview of management techniques shown to be effective on glossy buckthorn. For more detailed information on how to use these techniques, please visit our Management and Control page. For technical assistance on managing woody invasive species, please get in touch with a local cooperative invasive species management group.
Timing and spread concerns: Whenever possible, individual plants should be controlled before they are able to fruit in order to prevent spread. If control is undertaken when fruit is present, it is best not to remove the plants from the site to avoid spreading seed.
Physical control: Small plants are easily hand-pulled from moist soil; larger plants can sometimes be dug or pulled using equipment. The wet soil conditions preferred by glossy buckthorn can make physical removal more feasible than for other upland shrub species. Roots must be completely removed to prevent regrowth. Top-killing methods such as mowing, grazing, and prescribed fire are only effective when followed by foliar herbicide treatment of new growth.
Some landowners are experimenting with a non-chemical variation on the cut stump method for glossy buckthorn where the freshly cut stump is covered with a tin can or fully opaque plastic bag instead of applying herbicide. If installed correctly and left in place for one to two years, this method can prevent regrowth by blocking light to the cut surface (Minnesota Department of Natural Resources). If light is blocked for long enough, the roots will eventually die.
Chemical control and combined approaches: Foliar spray is the most feasible method for a large, dense infestation, and is effective anytime plants are actively growing and fully leafed out. This method can be used as a follow-up to mowing, grazing or another top-killing method when foliar herbicide is applied to regrowth later in the season. Cut stump, basal bark and stem injection herbicide treatments are all effective and can be applied during most of the year, outside of early spring. In all cases, herbicide should be selected carefully based on site conditions, and label directions read and followed carefully.
With any treatment it will be necessary to monitor for and treat regrowth and new seedlings in subsequent years. Managers should expect treatment of dense buckthorn infestations to be a long-term commitment.
Resources on management of glossy buckthorn:
- Bachtell, K. 2019. Interview on personal experience with Frangula alnus ‘Fine Line’ at The Morton Arboretum. 10/16/2018.
- Deppe, D. 2010. Response to: Are there non-invasive species of buckthorn? (Jaquart, EM and TM Knight). Indiana Nursery and Landscape News. May/June 2010: 16-17
- Dirr, MA. 1998. Rhamnus frangula. In: Manual of Woody Landscape Plants, Fifth Edition. Champlain, IL: Stipes Publishing. 840-841.
- Hilty, J. Rhamnus frangula. In: Illinois Wildflowers. 4/10/20.
- Knight, TM, Havens, K, and P Vitt. 2011. Will the use of less fecund cultivars reduce the invasiveness of perennial plants? BioScience. 61(10): 816-22.
- Minnesota Department of Natural Resources. Buckthorn management. 1/22/19.
Photo: Chris Moody via flickr.com