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Common Buckthorn and Glossy Buckthorn
NATIVE RANGE:
Eurasia.
Leaves of glossy buckthorn are entire, 1-3 inches long, shiny on the upper surface, oval shaped and slightly wavy. Flowers are 5-petaled, greenish white and the fruits are red, turning purplish black when ripe. Plants flower from late May until the first frost and fruits ripen from early July to September. Common buckthorn has smooth, deeply veined, oval leaves (1-2 1/2 inches long) with toothed margins. Common buckthorn is a dioecious species with male and female flowers on separate plants. Flowers are 4-petaled and yellow green in color; fruits are black. Flowering takes place from May through June and fruits ripen from August to September.
Several native American buckthorns that occur in the eastern U.S. that could be confused with the exotic species. If in doubt, consult with a knowledgeable botanist to get an accurate identification. Carolina buckthorn (Rhamnus caroliniana), is a lovely native shrub that has finely toothed leaves somewhat resembling those of black cherry, and are smooth on the underside; it produces attractive fruits from August to October. Alder buckthorn (Rhamnus alnifolia), is a low-growing shrub that may grow to a maximum of 3 feet in height, and has leaves with 6-7 pairs of veins. ECOLOGICAL THREAT: Exotic buckthorns tend to form dense, even-aged thickets, crowding and shading out native shrubs and herbs, often completely obliterating them. Dense buckthorn seedlings prevent native tree and shrub regeneration. In fire-adapted ecosystems such as savannas and prairies, the lack of vegetation under buckthorn prohibits fires. Buckthorn control is also of interest to small grain producers; the shrub is an alternate host of the crown rust of oats, which affects oat yield and quality.
HABITAT: Glossy buckthorn typically invades wetlands including swamps, bogs, fens and wet meadows but also occurs in upland habitats such as woodland edges, old fields and roadsides. Common buckthorn is primarily an invader of upland sites including open woods, woodland edges, prairies and open fields. Both species are capable of growing in full sun as well as heavily shaded areas. DISTRIBUTION: Glossy buckthorn and common buckthorn were introduced to North America from Eurasia as ornamental shrubs for fence rows and wildlife habitat and are still used in landscaping. These species are distributed throughout the northeast and north central U.S. Both species are frequent in the central and northern part of the state. BACKGROUND: Common buckthorn was introduced to North America as an ornamental shrub, for fence rows, and wildlife habitat. Introduction of buckthorn was based on its hardiness and ability to thrive in a variety of soil and light conditions. BIOLOGY & SPREAD: Common buckthorn is a dioecious plant, meaning that each plant produces only male or female flowers and fruiting trees are always female. Most of the fruits fall directly beneath the shrubs, creating a dense understory of seedlings characteristic of common buckthorn stands. The plentiful fruit is eaten by birds and mice and is known to produce a severe laxative effect, helping distribute seeds through birds, often far from the parent plant. Buckthorn often establishes beneath trees at the edges of forests and fields. SUGGESTED ALTERNATIVE PLANTS: For home landscaping and wildlife plantings many native low trees and shrubs are available from commercial nurseries. Examples include American elder (Sambucus canadensis), Black chokeberry (Aronia melanocarpa), and Juneberry (Amelanchier alnifolia). Please contact your local native plant society for recommendations of plants native to your particular area. AUTHOR and
EDITOR of the PCA-APWG WGW Fact Sheet: For more information
on exotic buckthorns, please contact: REFERENCES:
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