Buckthorn . . . the Gardener’s Foe

When buckthorn was first brought from Europe in the 1800’s, it was praised as the ideal shrub plant for creating hedges. That all changed when it began to plunder its way through our natural areas.

Like all invasive species, buckthorn lacks the natural controls, e.g. insects and disease that normally work to keep native plant populations in check. It’s also one of the first plants to foliate and one of the last to drop its leaves. As a result, it’s able to out-compete nearby plants for food, water and light, and quickly spreads over surrounding areas.

Buckthorn is spread by birds that eat and scatter its berries. When you consider that every one of the plant’s berries contains 3-4 seeds, each of which can remain viable in the soil for up to 6 years, it’s easy to see why buckthorn has become such a widespread problem.

The two types of buckthorn that are invasive are the Common Buckthorn and the Glossy Buckthorn.

Common Buckthorn (European Buckthorn)

  • Leaves: dull, oval-shaped green leaves; 1-2 inches long with fine teeth; leaves have distinct veins.
  • Twigs: tipped with thorns
  • Flowers: greenish yellow with four petals
  • Fruit: dark purple or blackish, ripen in late summer/early fall
  • Habitat: wooded edges, grazed and open areas

Glossy Buckthorn

  • Leaves: leaves similar in size and shape to Common Buckthorn, except they are shiny  and lack teeth
  • Twigs: tipped with thorns
  • Flowers: greenish-yellow with five petals
  • Fruit: dark purple or blackish; ripen in late summer/early fall
  • Habitat: wet prairies, marshes, meadows, sphagnum bogs, and tamarack swamps

Tips for Removal

  • Try killing young seedlings with a flame torch. Small shrubs do not have deep roots and can be hand-pulled or removed with a hoe. Wetting the soil beforehand or waiting until it rains will make it easier.
  • Glossy buckthorn can be tightly wrapped and eventually killed by cutting a 3 cm strip through the bark around the entire base of the trunk. This is a great option since it does not disrupt the soil, it will not cause the shrub to re-sprout, and can be done any time of the year.
  • Large shrubs (greater than 2 inches) should be cut as close to the ground as possible using a handsaw, and if possible, the entire stump removed. Plant the exposed soil, immediately, with a native tree or shrub.
  • If removing the stump isn’t possible, repeated cutting and removal of the resulting suckers will eventually kill the shrub. This will take time, so don’t give up.
  • Shrubs that have been removed should be burned or hauled away as waste refuse to prevent seeds from sprouting elsewhere.

The most persuasive reason to remove buckthorn is its effect on natural wildlife. Songbirds, rabbits, deer and squirrels find buckthorn less than desirable. Its tendency for making a thick, almost impenetrable mass on the forest floor and its lack of real nutritional value make it an unsuitable habitat for these animals. They will not spend much time in an area overgrown with buckthorn, especially if there are more desirable areas nearby.

In early March (2011) Independence County Park (Oakland County Michigan) will perform a “controlled burn” to eliminate invasive plants like buckthorn. The burn will promote better growth of native plants and provide a suitable environment for the animals.

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