common buckthorn stem with fruit Common buckthorn stem with fruit

Common Buckthorn

Rhamnus cathartica

2019 Status in Maine: Widespread. Severely Invasive.

Description: Perennial, deciduous shrub or small tree, often multi-stemmed, can be single-trunked, to ~25' tall. Despite name, lacks thorns; has small spines (up to 78" but usually < ½") at very end of most twigs.

Leaves: Simple, sub-opposite, some more nearly alternate or opposite, elliptical to almost round, toothed, with arching leaf veins, pointed tip, 1-3" long. Flowers: Small, white-green, 4-petaled, in clusters at leaf bases along stems, appear in ~June in Maine. Fruit: Round, ¼ - ½" wide, mature from green to a glossy black color in late summer. Bark: Mature plants have horizontal, lighter-colored lenticels on brownish-gray bark. Larger plants have orange inner bark.

Native range: Europe and Asia. How arrived in U.S.: As an ornamental; wind break and hedge plant.

Reproduction: By seed. Plants are usually dioecious; males do not produce fruit. Fruits are eaten by birds, mice, and deer. Seeds viable for 2-6 years.

common buckthorn flowers Common buckthorn stem with flowers

Habitat: Forests, forest edges, old fields, open areas. Shade-tolerant; will germinate, grow, and reproduce under full canopy. Tolerant of moist to well-drained soil.

Similar native species: Alder-leaved buckthorn (Rhamnus alnifolia) has larger leaves that are opposite along the stem, 5-petaled flowers, and is a low shrub (<5') of wetlands. Cherries (Prunus spp.) have lenticels but scratched bark or twig has characteristic bitter almond smell and leaves are consistently alternate. Winterberry holly (Ilex verticillata) has alternate leaves, bright red fruits, and prefers wet soils. None have orange inner bark.

Similar non-native species: Glossy buckthorn (Frangula alnus) leaves are entire, twig ends have no spines, can have both red and black fruit at once, and lacks orange inner bark. Apples (Malus spp.) have alternate leaves and leaf venation that is not as pronounced.

Fact Sheets and Identification Links

Rhamnus cathartica leaf stipules Common buckthorn stem showing leaf stipules

Control Methods

Small plants and seedlings may be pulled up by the roots when soil is moist; larger plants can be cut, but re-sprouting will occur.* Persistent cutting or mowing multiple times during the growing season over several years may kill the plant, but diligence is required (at least 3x/yr for 3 yrs is suggested). Mowing can prevent seedlings from establishing. Common buckthorn keeps its leaves late into the fall after native plants have dropped theirs. Foliar applications of glyphosate aare very effective during this period. Herbicides can also be applied as cut-stump applications (glyphosate or triclopyr solution applied immediately after cutting except in early spring), or basal bark application (for stems <6" diameter, triclopyr ester in bark oil).

* Correctly dispose of all plant parts † Follow all label directions when using herbicides

Control Technique Video Demonstrations

Please email invasives.mnap@maine.gov if you have questions about invasive species in Maine

Rhamnus cathartica fruit Common buckthorn fruit
Rhamnus cathartica terminal thorn Terminal thorn-like spine on common buckthorn, Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Rhamnus cathartica branch Common buckthorn branch