Tuesday, July 12, 2016

Invasive Species Spotlight: English Ivy

Guest post by Jacqueline Hyman

Although many people may enjoy planting English Ivy as a ground cover in their yards, the plant is an invasive species that weakens trees and can carry disease.

    English Ivy (Hedera helix) is an “evergreen perennial climbing vine that attaches to bark of trees … and other surfaces by root-like structures that exude a glue-like substance to aid in adherence,” according to Plant Invaders of Mid-Atlantic Natural Areas, a guide to invasive species created by the National Park and U.S. Fish and Wildlife Services.

    This plant, which was introduced mainly by European colonists in the early 1700s, is favorable to many who enjoy a perennial ground cover that does not require much maintenance. It thrives in the eastern U.S. region and can be identified by its dark green and waxy leaves, which typically have whitish veins.

    “It’s very care-free, when you think of having to take care of something and keep it looking good,” said Carole Bergmann, the forest ecologist and field botanist at the Montgomery County Parks system. “If you’ve got a bare spot, it’ll cover it for you and stay green year round.”

    However, because of these same admired qualities, Bergmann said the plant is also “a terrible problem for natural areas.” English Ivy invades many of the 417 parks in the Maryland National Capital Park system when people grow the plant in their yards on the edges of the parks, Bergmann said. Birds and other animals, which eat the seeds, also spread the invasive vine.

    Many home gardeners, Bergmann said, throw the plant trimmings over their fences and onto the park property.

    “They think that’s no problem, they think it’s going to disintegrate and turn into compost,” said Bergmann, “and often English Ivy will re-root and go up the trees.”

    Bergmann said the plant poses two main problems: firstly, it prevents other native species from growing when it covers the ground. Secondly, the vine covers trees, weakening them and making them heavier in the wind, allowing them to blow over easily.

    According to Plant Invaders, the vine also impedes photosynthesis because it blocks the tree’s access to sunlight. Additionally, the ivy is likely to harbor diseases, such as bacterial leaf scorch (Xylella fastidiosa), according to the book.  

   The leaves and berries of English Ivy are toxic if ingested, according to the book, and may cause a variety of symptoms including diarrhea, fever, and breathing difficulty.

   In the county parks, Bergmann often enlists volunteers to help remove English Ivy because it takes a large amount of time. “English Ivy is more of a tedious job to get it off … individual trees,” Bergmann said. “[It] has roots that dig into the tree bark.”

   Bergmann strongly urges gardeners to avoid planting English Ivy in their yards, but understands that people enjoy an easily maintained plant as ground cover.

“If they … want to plant English Ivy in their yard,” she said, “the way that they can contain it is to let it just grow on the ground in their yard and not let it go up to trees.”

The  "Invasive Species Spotlight" is a summer blog series focusing on a different plant each week that is a problem for Mid-Atlantic home gardeners.

About the author:
Jacqueline Hyman is a junior journalism and English major at the University of Maryland. She is the editor-in-chief of the Mitzpeh, an independent Jewish newspaper at UMD. In addition, Jacqueline enjoys musical theater, and teaches piano and voice at Guitar Center. She is excited to be interning this summer for the Washington Gardener.

4 comments:

Anonymous said...

The reason it is okay to let it grow on the ground but not up trees is because it only flowers and makes fruits/seeds if it grows up something. The birds eat the fruits and disperse the seeds to natural areas.

Anonymous said...

Any tips for removing it from trees and garden beds?

Vin de Terre said...

A lot of what is identified as English Ivy (Hedera helix) is actually Irish ivy (Hedera hibernica); but the problems are the same. For the difference, google it and read the article in the Washington Post. There are useful instructions for eradication in the comments to that article, as well.

Anonymous said...

How can you get rid of it? It seems impossible. Even Round Up doesn't do the job.