Multiflora rose, purple loosestrife, water hyacinth, Callery pear trees… These plants are known to be invasive thugs, and yet they are still sold at garden centers. Some are “over the fence” divisions between well-intentioned neighbors and casual gardeners. And then… these plants SPREAD where they aren’t wanted, often rapidly, from roots or plentiful seeds. Most invasive plants are very difficult to remove, and the process may take years of on-going effort.
Why would anyone want such a plant in the first place? Usually ignorance gets the credit. Folks see a pretty flower, or a shrub that will suit a certain purpose in the landscape, and they have no idea they’re about to share it with the entire neighborhood. The road to hell is paved with Japanese honeysuckle! From the Ohio Invasive Plant Council (website links, below):
“The introduction of many non-native plant species was well-intentioned. Some had medicinal qualities, others were valued in horticulture, for forage, and for erosion control. Other species arrived by accident - stowaways in cargo and ballast. Potential for invasiveness was neither known nor considered. Human population growth, environmental alteration, and the vast increase in worldwide trade have created more opportunities for the introduction and spread of invasive species.”
I hear people say, “At least it’s a green plant that looks healthy, grows along the highway, and provides berries for wildlife! And hey, isn’t natural selection a thing?” The problem is that invasive plants have an unfair advantage over native plants, and provide little or no upside to the native ecosystem. Plants and wildlife (insects, songbirds, mammals, etc.) co-evolved over millennia for their mutual benefit: In exchange for food (pollen, say, or seeds), animals help disperse the plants to new areas. The animals thrive from the nutrition and produce healthy offspring. When they’re in balance, no one species dominates to the detriment of the ecosystem. There are enough resources – and variety of resources – to create a wide range of vibrant biodiversity.
Along comes Japanese honeysuckle. (Can you tell I hate Lonicera sp. japonica?) It grows quickly, creates a pleasant hedge, and smells nice in spring. Birds discover the plump berries and Japanese honeysuckle begins to appear alongside rivers and railways, in ravines, and pretty much anywhere birds like to go. The seed germinates quickly and within a year or two, it shades out pretty much everything around it. Soon one shrub is five, then fifty, and soon you can’t see the ground any more. Sun, shade, wet, dry… it’s happy wherever it lands. Native plants aren’t capable of competing with this alien marauder and so they die out.
Wildlife biologists are finding birds with bellies full of honeysuckle berries and yet the birds are malnourished. Why? Because our native birds didn’t co-evolve with this species of honeysuckle and therefore can’t extract the nutrients they need to thrive and produce offspring. The plants they do need have been replaced by large stands of honeysuckle, and so they eat the berries. Because hey, natural selection is a thing and everybody’s gotta eat to survive!
Remember that what affects the lower levels of the food web (fungus, plants, insects, and so on) ripples up to affect every level above it, either through diminished vitality and/or a smaller population of individuals.
After learning about some of these invasive species, it can feel like an OVERWHELMING problem – can we possibly get rid of these thugs and marauders? But despite the “doom and gloom” tone of some environmental websites, remember that there are success stories – wilderness areas that have eradicated (or at least greatly reduced) plants like buckthorn and multiflora rose and reed grass, and have increased the populations of native plants to healthy levels.
What can you do in your home landscape? Learn the habits of the plants you choose to grow, and if you find an invasive one, throw it in the trash! Do not put it in the compost, because most invasive plants will think you’re sending it to fitness camp.
If you’re interested in controlling invasive plants in cool and isolated Ohio wilderness areas, and want to meet some awesome, fun-loving, plant-killing people, sign up to join a monthly removal project with The Nature Conservancy, ONAPA (OH Natural Areas & Preserves Association), or ODNR (the OH Dept of Natural Resources).
NOTE: There’s a TON of resource info on the OIPC and ODNR websites including photos and fact sheets of invasive plants and noxious weeds, area workshops around the state, and resources for neighboring states. Many of these resources are directed at home gardeners (not just park managers or farmers) and offer alternative plants to use in place of invasive species.