English Ivy

English ivy, Hedera helix, is an invasive species in Washington and Oregon. It takes over areas very easily and shades out other plants.⁷ It also climbs up trees adding weight and weakening them. It also spreads very rapidly and is ground cover as well as being a climbing plant.¹ Because they have very shallow roots and crowd out other ground plants soil can become eroded and poor.⁸

Synthetic figure: distribution of English ivy in the US

The plant was native to Europe and was most likely brought over as an ornamental.³ Although the ivy has been found on both coasts, it is very invasive in the Pacific Northwest.⁵ Many people do not understand how destructive this plant can be, although it has been qualified as a noxious weed in Washington.¹⁰ One of the reasons it is so invasive in Washington state is because it is particularly good at growing in shady areas.⁶ This could also be why it is popular as an ornamental plant that people keep around.

Trees covered in ivy

 Although it is very fast spreading it is also easy to kill. Its roots are very shallow and when pulled out or have an herbicide used on it the plant will die. However, it is often hard to get rid of because it has such a large distribution and as ground cover it is intertwined with many other plants.

Ivy on a brick wall

One of the most dangerous things about English ivy is that it dramatically decreases biodiversity. When the ivy gets established it makes it difficult for small plants to survive around it and eventually it will even take down trees.⁹ To prevent spreading it is essential to ensure the ivy does not bloom, which happens when the ivy gets enough sunlight.⁶ To stop that the ivy must be taken down before it climbs high enough on trees.