Frangula alnus (Glossy Buckthorn)
|Also known as:||Columnar Buckthorn, Fen Buckthorn, European Buckthorn, Alder Buckthorn|
|Life cycle:||perennial woody|
|Habitat:||part shade, shade, sun; moist; woods, wetlands|
|Bloom season:||May - September|
|Plant height:||to 20 feet|
|Wetland Indicator Status:||GP: FAC MW: FACW NCNE: FAC|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Clusters about 1 inch across in the leaf axils of new growth, 2 to 8 flowers in a cluster. Flowers are perfect (both male and female parts present), yellowish or greenish white, about 1/8 inch across on a stalk ¼ to 1/3 inch long, with 5 erect, triangular sepals, 5 white tipped stamens and single style.
Leaves and bark:
Leaves are simple and alternate, the blade oblong elliptic, 1½ to 3 inches long and 1 to 1½ inches wide, tapered at the base, the tip rounded or with an abrupt point, toothless and often wavy around the edges, the upper surface glossy, lower surface smooth or finely hairy on the veins, on a ¼ to ¾ inch stalk. The 6 to 9 veins per side are strongly parallel to each other before curving abruptly towards the tip at the leaf edge. Leaves can turn a bright golden, at least in part, in the fall though often remain green until cold temperatures freeze them off the tree.
The trunk can be single but more often multiple from the base; a single trunk is rarely over 4 inches in diameter and clusters of multiples are typically more slender. The bark is dusky to dark gray, splotched to various degrees by lighter patches of aged, sometimes warty lenticels (pores), the cambium (layer of tissue just under the bark) is a greenish yellow, the center heartwood reddish orange.
New growth is reddish green with minute hairs and prominent white vertical lenticels, the 2nd year twigs becoming brownish with flaking gray bark, the dormant twig tips with minute brown fuzz-like hairs. There is no thorn present. The older branches turn a dusty gray brown with splotchy white lenticels. The roots are a distinctive red.
Fruit is a red berry, turning shiny black when ripe, ¼ to 1/3 inch in diameter on a short stalk, with purplish flesh surrounding 2-3 seeds in the center. The fruit is readily consumed by birds which spread this invasive species through their droppings.
Glossy buckthorn was imported from Europe in the early 1900s as a landscape shrub. It was not widely disseminated in the nursery trade in Minnesota until the mid to late 70s. Popular cultivars of it had narrow, columnar forms or fine feathery foliage with names like Tallhedge Buckthorn and Fernleaf Buckthorn. All of these cultivars produce fruit with viable seeds that are spread by birds, and within one or two generations revert back to the natural, small spreading tree form that is aggressive in the landscape. Concerns in Minnesota over environmental damage due to the rampant spread of both buckthorn species into natural areas came to a head in the late 1990s when Common Buckthorn was listed as a restricted noxious weed in 1999. While this was fiercely opposed by the nursery industry, Glossy followed suite in 2001 thanks to the equally ferocious passion of Mary Maguire Lerman (Buckthorn Mary) of the Minneapolis Parks and Recreation Board. Ultimately Glossy Buckthorn itself may prove to be the most ferocious invader. It is very aggressive in both upland forests and wetlands like rare fens and tamarack bogs and even tolerating dry, sandy prairie habitats. Unlike Common Buckthorn that takes several years to regenerate fruiting branches after being cutback and produces only one crop of fruits per season, Glossy easily flowers and fruits on first year suckers, and produces flowers and fruits all season long. While many in the industry still today lament the loss of this commodity, buckthorn control continues to eat up an disproportionate amount of many resource managers budgets for which the responsible parties have never had to pay a dime.
Dormant identification for this species is important. Look for the dull gray bark with varying degrees of patchy white and roundish lenticels throughout twigs, branches and trunk. The twigs are thornless and covered by fine, brown wool-like hairs and while the cambium under the thin bark is not as deeply colored yellow-orange as Common Buckthorn, the heartwood is clearly a similar reddish-orange, and the roots are a distinctive red.
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- berry-laden shrub
- regrowth following untreated cut stump
- more leaves
- Glossy Buckthorn dormant twig, buds and bud scar
- Glossy Buckthorn roots
- Glossy Buckthorn seedlings
- woodland invasion of Glossy Buckthorn
- wetland invasion of Glossy Buckthorn
- Buckthorn branches vs. Black Cherry
- Buckthorn wood colors vs. Black Cherry
- Buckthorn cambium colors vs. Black Cherry
- November color
- Japanese beetle eats Glossy Buckthorn!
- fern-leaf cultivar of Glossy Buckthorn
- columnar form in a home landscape
- columnar form escapes cultivation, too
Photos by K. Chayka taken in Anoka and Ramsey counties. Photos courtesy Peter M. Dziuk taken at locations across Minnesota
Have you seen this plant in Minnesota, or have any other comments about it?