European buckthorn: a tenacious renegade

Nonnative buckthorn takes over habitats

  • An immense wall of European buckthorn stands to the side of a path at LeRoy Oakes Forest Preserve in St. Charles. Nonnative and invasive, buckthorn is a fast grower, and chokes out native trees. Because it spreads quickly and grows so fast, it is a constant battle to clear it from the forest preserves.

      An immense wall of European buckthorn stands to the side of a path at LeRoy Oakes Forest Preserve in St. Charles. Nonnative and invasive, buckthorn is a fast grower, and chokes out native trees. Because it spreads quickly and grows so fast, it is a constant battle to clear it from the forest preserves. Laura Stoecker | Staff Photographer

  • The leaves of the nonnative and invasive European buckthorn.

      The leaves of the nonnative and invasive European buckthorn. Laura Stoecker | Staff Photographer

  • Berries identify this European buckthorn as a female.

      Berries identify this European buckthorn as a female. Laura Stoecker | Staff Photographer

 
By Valerie Blaine
Forest Preserve District of Kane County
Updated 11/5/2011 9:47 AM

As the spectacular pageant of autumn draws to a close, there's a tree that refuses to exit the stage.

Its tenacious green foliage stands out among the newly leafless trees. The renegade is European buckthorn.

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Easily spotted this time of year, European buckthorn is a nonnative plant that's made itself quite at home in the Midwest over the past century.

Notorious for its role in diminishing habitat quality, the ubiquitous buckthorn presents both a challenge and an opportunity wherever it grows.

Buckthorn originated in the Old World where it was well-known for its many uses. According to the herbal website herbco.com, Greeks in ancient times used buckthorn "for protection from demons, poisons and witches."

Aside from these dubious claims, the berries and bark have scientifically validated applications. For example, they yield a yellow pigment that was used in mapmaking. The pigment was also a component of watercolor paints.

Most notable in the natural history of buckthorn is its role in the pharmacopeia of Europe and the early United States.

The scientific name Rhamnus cathartica reveals the plant's purgative qualities. The active components rhamnocathartin and rhamnin, present in both the berries and the bark, produce the aperient effects.

                                                                                                                                                                                                                       
 

Medicinal syrup from buckthorn was bitter to the taste and nauseating to smell. Evidently the syrup was not administered to the faint of heart. Herbalist Maud Grieve quoted a 16th-century herbal saying, "They be not (meant) to be administered but to the young and lusty people of the country which do set more store of their money than their lives."

Buckthorn made its debut in North America in the 1800s. Knowledge of the plant's medicinal uses in the Old World aided its establishment in North America. The primary reason for importing buckthorn, however, was for use as hedgerows. As such, it was an immediate hit. Buckthorn established itself well in a variety of soils, and it grew fast and dense, making an effective visual and physical barrier.

Despite its practical applications, buckthorn is a classic case of good intentions with not-so-good outcomes. Soon after its arrival in North America, buckthorn gained a foothold in our plant communities and held its ground. Fecund female trees produce thousands of berries, with four seeds apiece. These are relished by birds who -- not reading the label -- don't realize the seeds' laxative effect. Thus millions of seeds are spread by berry-binging birds with stomach aches. The seeds are quick to sprout, and now buckthorn trees are firmly established in every township of Kane County -- and all over northeastern Illinois, Wisconsin, Michigan and many states to the east.

Why has this once-desirable plant fallen from grace? The very reason for importing buckthorn -- creating dense hedgerows -- is its downfall. Because buckthorn tends to grow in dense thickets, it produces impenetrable shade. The dense canopy prevents sunlight from reaching the ground. This leads to a cascading series of ecological effects.

                                                                                                                                                                                                                       
 

Without sunlight, native wildflowers die. Sun-loving oak and hickory seedlings are doomed. The soil under the dense canopy of buckthorn becomes bereft of vegetation. With nothing to hold the soil in place, heavy rains wash the soil away. An area once flourishing with a diverse array of majestic native trees and resplendent wildflowers becomes a biological desert, a monoculture of only one green growing thing: buckthorn. Left to its own devices, buckthorn would take over the majority of our natural areas in short order.

Enter habitat heroes, the natural areas managers, restoration ecologists, and scores of dedicated volunteers. The Forest Preserve District of Kane County and partner agencies such as the St. Charles and Geneva park districts implement year-round management plans which include removal of buckthorn and its equally invasive counterparts such as autumn olive and honeysuckle. The assault begins with bow saws, loppers and chain saws. The second line of attack is herbicide to knock back aggressive re-sprouts. Prescribed burns are used as an ongoing management tool to keep buckthorn and friends from re-establishing.

Success stories abound, where land once choked with buckthorn thickets is now a renascent woodland. Young oak and hickory trees stretch tall in the open woods. Spring and fall wildflowers flourish in the dappled sunlight that once again reaches the forest floor.

Volunteer Tim Balassi has experienced the "before and after" of buckthorn removal at numerous forest preserves, and he's impressed by the difference.

"We removed a lot of buckthorn at Bliss Woods," Tim said. "This (made) way for Hepatica, Baneberry, Snakeroot, etc." Tim and fellow volunteers also cut buckthorn at Glenwood Park and Les Arends Forest Preserve, opening up thickets under which native vegetation had been suppressed for years. Marsh marigold, Joe Pye-weed and skunk cabbage now have ample sunlight -- and room -- to grow.

Buckthorn, like any plant moved from its place of origin, is not inherently bad. It is misplaced. In its homeland, buckthorn was a plant that played a positive role in both human culture and ecology. Complete eradication of buckthorn from our natural areas is unlikely, but the problem can be turned into an opportunity.

In the hands of a woodworker, buckthorn can be transformed from something undesirable into something of beauty and value. Buckthorn wood is hard, dense, and has an attractive burnt red/orange grain. It has been used for "attractive fencing, furniture, sculpture and even kitchen utensils," according to a panel of presenters at a 2005 Chicago Wilderness conference.

In "European Buckthorn: Problem for Ecosystems, Opportunity for Woodworkers," Barry Gordon wrote, "Historically (buckthorn) has been used for tool handles and small turned objects." He is spearheading research to explore the characteristics of buckthorn wood for other uses.

"A goal of the research," Gordon said, "is to publicize the species as a source of attractive wood in an effort to increase harvesting and diminish its threat."

Thus, while The Battle of Buckthorn is being fought on many fronts, there is promising potential for transforming the vanquished into something useful -- and beautiful. If you've found ways to use buckthorn -- wood, leaves, bark or berries, drop me a line and I'll share those ideas in my next column. Who knows, with a plentiful supply of raw materials, buckthorn Christmas presents may become quite the rage this holiday season.

Valerie Blaine is a naturalist with the Forest Preserve District of Kane County. Email her at blainevalerie@kaneforest.com.

                                                                                                                                                                                                                       
 

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