Before coming to Ohio State University Extension, I worked as an interpretive park ranger in Cuyahoga Valley National Park where I spent sweltering summers dressed as Smokey Bear.
My primary duty as a park ranger (aside from directing visitors to the nearest restroom) was to teach the public about environmental issues like water quality and invasive plants. I found that most people knew at least a little bit about Northeast Ohio’s turbid water quality history (burning rivers are not easily forgotten). What surprised me, however, was the public’s lack of knowledge about an environmental issue so prevalent that it’s literally growing right before our very eyes — invasive plants.
An invasive plant is a plant that is non-native and has the ability to cause environmental or economic harm or harm to human health. I am often asked whether a native plant can be invasive. Consider, for example, poison ivy. Though native, poison ivy can grow quite prolifically and, for those who are allergic to the oils, can cause a nasty rash.
I always urge people to look beyond definitions and focus on the harm that the plant does in the environment. If poison ivy is taking over an area of more desirable plants, or if you’re highly allergic, consider removing the plant (but keep in mind that poison ivy provides valuable food sources for wildlife, so only remove if absolutely necessary).
Besides being non-native, other characteristics of invasive plants include their ability to spread and out-compete native plant populations. By out-competing native plants, invasive plants replace vital wildlife food sources and habitats, altering food chains and changing ecosystem composition.
From flowers and shrubs, to large trees, invasive plants come in many shapes and sizes. Some plants are universally agreed upon as being invasive (garlic mustard and multiflora rose, for example). Other potentially invasive plants are touted as great ornamental options. Below is a list of the top 10 invasive plants in Ohio according to the Ohio Department of Natural Resources:
• Japanese honeysuckle (Lonicera japonica)
• Japanese knotweed (Polygonum cuspidatum)
• Autumn olive (Elaeagnus umbellata)
• Buckthorns (Rhamnus frangula and R. cathartica)
• Purple loosestrife (Lythrum salicaria)
• Common reed (Phragmites australis)
• Reed canarygrass (Phalaris arundinacea)
• Garlic mustard (Alliaria petiolata)
• Multiflora rose (Rosa multiflora)
• Bush honeysuckles (Lonicera maackii, L. tatarica, L. morrowii)
Other plants known to cause problems in natural areas include Chinese and European privets, Callery pears (including Bradford pear), Japanese barberry, crown vetch, dame’s rocket, tree-of-heaven, teasel, and Canada thistle.
Don’t get caught up in invasive plants lists and definitions. I encourage you to keep a close watch on all the plants you put in your landscape. If you notice something becoming problematic, take action.
Some invasive plants simply don’t do well in a particular spot so they may not cause problems for you. Keep in mind, however, that just because a plant isn’t causing a problem in your yard, doesn’t mean that plant isn’t causing a problem for someone else in another part of town. Many plants spread when birds and other wildlife consume the fruits. Also, rivers and streams act as highways for the seeds of water-loving plants like purple loosestrife, aiding in their spread.
If you need help identifying a problem species in your yard, or would like additional information about how to control and remove invasive plants, call your local county extension office.
Danae Wolfe is the Ohio State University Summit County Extension Educator for Agriculture and Natural Resources. If you have gardening questions, she can be reached at 330-928-4769, ext. 17, or wolfe.540@osu.edu.