#24 Connecticut Invasive Plants
In the processes of moving the cactus garden the madman made an unpleasant discovery. Invasive plants were sneaking into the area surrounding the former cactus bed. I saw him walking towards me with a handful of greens. He didn’t look very happy. As he got closer, I noticed the orange roots – Bittersweet! Then I knew the cause for his agitation.
“That’s not all,” he said as he dragged me over to inspect. Oriental bittersweet (Celastrus orbiculatus) was growing up a Burning bush (Euonymus alatus) AND Japanese honeysuckle (Lonicera japonica) was twining itself in a Multiflora rose (Rosa multiflora). Right in front of our eyes we had four of the plants listed as invasive in Connecticut.
This Shouldn’t Happen
How could this happen to us? After all, we are master gardeners, we should know better. Through the Master Gardening program we learned a great deal about invasive species. We know they harm our environment, and we thought we were being vigilant about detection and removal. But here they were, happily growing-apparently getting ready to take over.
So, what’s the big deal? And, why are these good-looking bug free plants shunned by the gardening world? They are invasive. The formal USDA definition of an invasive species (plants, animals and insects) is, “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” Sounds rather sterile, doesn’t it? The madman prefers to think of invasive plants as vigorous growers with no enemies that out compete native plants and disrupt the ecological system.
Accidental Problems
The horticultural world introduced most of the invasive plants into American gardens for their beauty and vigorous growth. Since they were from a different world, our native animals and insects had not developed a taste for them – an extra benefit, they were relatively bug-free. What seemed like a good idea at the time of our Victorian ancestors turned ugly really quick. Some of these plants were real bullies and took over entire areas of our landscape. The over-abundance of invasive plants is creating an ecological nightmare – if native creatures can’t use these plants to feed and reproduce, they will move on and our outdoors will get pretty quiet.
What Does It Matter?
The madman makes a big deal about this because he likes his native environment. Thankfully, he is not alone. In 1997, the Connecticut Invasive Plant Working Group (CIPWG) was formed to increase invasive plant awareness and advocate native and non-invasive alternatives. Part of their mission is to promote reliable alternatives to invasive species. The group suggests that although burning bush does give nice red fall color to your landscape, so does the native high bush blueberry.
The CIPWG website contains a complete list of Connecticut invasive plants. Since we don’t contend with all the plants on the list, we are only going to address those that we find in our own yard.
Oriental Bittersweet
Oriental bittersweet (C. orbiculatus) was first introduced in 1860. Gardeners loved it because of its beautiful fall berries-a yellow coating that opened to expose orange berries. This prolific vine quickly covered trellises. Bittersweet’s fall cover made it a favored choice for decorations. Birds quickly developed a taste for its berries which would stay in their guts for 14-42 days. Because of this, the seeds spread over long distances very quickly.
As this plant grows, it uses trees for support – quickly girdling the trees as it twines to the top of the canopy where it spreads across treetops. The bittersweet leaves block available sunlight eventually causing its host to die. We have been fighting this vine almost as long as we have fought the Japanese honeysuckle (L. japonica) that was actually planted in our yard by a previous owner.
Japanese Honeysuckle
This trailing woody vine with its fragrant flowers has been highly prized since its introduction in the early 1900’s. It is an excellent plant for erosion control and ground cover. An established planting of honeysuckle can engulf small trees and shrubs, killing them. Because it grows in a dense mat, this honeysuckle shades the understory which chokes out many native species. Left alone, this vigorous vine will quickly take over the entire landscape as the madman discovered in our own yard. After 40 years of fighting it, we still find patches here and there. The latest outbreak was next to the old cactus garden where it was attacking a Multiflora rose (R. multiflora). And, that’s the next invasive we are dealing with.
Multiflora Rose
If the truth be told, I used to love this rose. I cut bouquets for the house during its flowering period. And then, it produced such nice clusters of rosehips in the fall. I was devastated when we learned it was invasive, but I noticed the glee in the madman’s voice when we decided to get rid of it. Good thing, too, because left alone it can grow 1-2’ per week forming an impenetrable thicket of thorns.
It spreads by runners and by birds. In the case of this rose, the seed remains viable for over 20 years. It can tolerate a wide range of conditions, so it seems to spread everywhere, destroying native species by simply taking over. As beautiful as it is, the Multiflora rose (R. multiflora) is not the best choice for a Connecticut landscape. We could say the same about Burning bush (E.alatus).
Burning Bush
Who doesn’t love the brilliant red fall leaves of this plant which was introduced as an ornamental in 1860? It is a prolific grower which can tolerate many different conditions, making it a problem in the natural landscape. With no known predators and the ability to produce numerous seeds, a single plant can quickly turn into a large colony, again crowding out native species. As aggressive as this plant is, it can’t hold a candle to Japanese knotweed (Reynoutria japonica).
Japanese Knotweed
Although Japanese knotweed (R. japonica) contains some proven medical benefits, this plant is not kind to the Connecticut environment. It was introduced in the late 1800s as an ornamental and an erosion control plant. But by the 1930s scientists realized that this was a mistake. In addition to being a rapid grower, Japanese knotweed (R. japonica) produces a toxin to suppress the growth of surrounding plants. Unfortunately, in Connecticut, you don’t have to travel very far to find a healthy stand of this weed.
Since we are on the topic of Asian invasive shrubs, next up is Japanese barberry (Berberis thunbergii).
Japanese Barberry
Like the shrubs we have mentioned, Japanese barberry (B. thunbergii) was introduced in the 1800s: its claim to fame was “Deer resistance”. What Connecticut homeowner could resist? Unfortunately, it escaped and began shading out native plants. What tipped the scales for the madman was its implication in the spread of Lyme disease. It seems that white footed deer mice, the carriers of the deer tick larvae, congregate under this barberry. Studies have shown a higher incidence of infected tick populations where Japanese barberry (B. thunbergii) is prevalent. All the reason the madman needed to start pulling this plant.
While the vines and shrubs we have been talking about shade native woodland plants, there is a larger invasive species that shades everything: the Norway maple (Acer platanoides) , once a prized shade tree.
Norway Maple
This stately ornamental is native to Europe and Asia, sound familiar? The Norway maple (A. platanoides) was brought over as an ornamental, but experience has shown its problems. As a fast growing, shade tolerant tree, it can quickly take over a woods. Because of its dense, shallow root system it is difficult for other plants to grow near it. More importantly, native insects don’t feed on its leaves and native mammals don’t eat the seeds. Studies from Vermont have shown that it is a good host plant for the Asian long horned beetle (Anoplophora glabripennis), another invasive species.
While you can still purchase this monster, the madman would prefer to eliminate it before it destroys the maple sugar industry by killing native Sugar maple (Acer saccharum) trees. Last on the list of invasives in this discussion is the Glossy buckthorn (Frangula alnus).
Glossy Buckthorn
By all accounts, the Glossy buckthorn (F. alnus) is a beautiful tree – shiny green leaves, the ability to fruit and flower at the same time, vigorous growth. Like all the other invasives, this tree is a fast grower that creates dense thickets and threatens native understory shrubs, plants and trees. It also serves as a host for crown rust fungus and the Soybean aphid. Although the madman doesn’t grow these crops, he feels there are plants better suited for the environment.
Noxious but not Invasive
The madman would like to mention one more plant – we find it all over our yard. A vigorous grasping vine that produces beautiful yellow leaves and whitish berries beloved by birds in the fall, Poison ivy (Toxicodendron radicans) is not an invasive vine. Rather, it is an important plant in the ecology of the madman’s yard. Birds use the berries as an important food source in the winter months and what is good for the birds is good for the madman. He does try to keep the vines from his paths and garden beds, but lets it grow freely in areas that are not traveled.
Seems like we have a lot of bad plants growing in our yard, but we have only scratched the surface of the invasive plant list. There are over 100 in Connecticut alone. If you don’t have these invasives growing in your yard, consider yourself lucky. The best control is to not plant them in the first place.
We All Need to do Something
However, if you do have them, it is time to create a plan to get rid of them. Hand pulling is not the only option, but it is the safest. For a good article on eradication methods, the Connecticut River Coastal Conservation District has prepared a comprehensive booklet Connecticut Invasives in Your Backyard which is available for download. The University of New Hampshire Extension has also prepared a good resource on managing invasive plants.
If you want to feel real good, the madman suggests you get in touch with a local Land Trust or other environmental organization that sponsors invasive eradication days. Volunteer some time, exert a little effort and feel good about helping preserve our natural environment. Your grandkids will thank you.
Time for lemonade.
