Michigan’s Department of Agriculture and Rural Development (MDARD) is considering updating its list of invasive species to include six trees and shrubs that you’ve probably seen in your neighborhood or local park. The current list is very short, but could soon include species like the callery pear, an ornamental tree with white flowers and a notoriously bad smell.
The state is accepting public comments through an online form until Monday, February 9. Other proposed species include Japanese barberry, common buckthorn and glossy buckthorn, water hyacinth, and water lettuce.
Stateside’s April Baer spoke with Lawrence Law, a forester with Michigan’s Department of Natural Resources, about what’s best for your garden and the environment.
Answers have been edited for brevity and clarity.
Q: What kind of threats do these species pose in Michigan?
A: We kind of started with these six because they were the most relevant to cause environmental, economic and human harm because they spread so much. They're species that we've seen in other states that have taken the lead in banning them. So it's been our recommendation for them to finally be regulated in Michigan.
Q: You mentioned human harm. What kind of human harm can these plants cause?
A: They're not the reason for human harm, but they facilitate it. For example, Japanese barberry. There have been studies out there that they are perfectly designed to essentially be a condo for the black legged tick, which spreads Lyme disease. So we see as that spreads, we could also see a correlation with the spread of the disease.
Q: I had never thought that there might be trees that should not be planted. How do you know if the trees that you're thinking about trying in the backyard might be invasive or, at minimum, undesirable?
A: When we say invasive, we think of what is recommended by our joint venture with MDARD and the DNR here. Black locust and tree of heaven are two invasive trees in the state where we have the studies and we have the data proving they’re harmful.
All these other species are more “invasive potential.” And we go through with more rigorous and scientific assessments to determine whether or not they are. So a lot of those “invasive potential” species are a “wait and see.” We haven't done those rigorous studies yet, but we are going to keep an eye on them. And that's why we really want to reach out to the public with these species to see if the public has any feelings about them, if they really love them so much.
(Check out the state’s tree species selection guide to learn more about undesirable — and desirable — trees in your community.)
Q: Let's say I look at these different trees that are invasive or undesirable, and I realize that maybe I've got some of those trees on my property, or there's one nearby. What are you recommending that people do about that?
A: I recommend you just enjoy it. It's something that's already there. It's usually a high cost to remove those sorts of trees. So I say enjoy it until it's gone and then just learn from that and grow and plant something different. It's a good opportunity to take a look at, “hey, this is what I liked from this, but maybe it wasn't right for the environment.” These restrictions are not about saying “everyone rip up all your plants because they're not good.” Enjoy it because they really do have a lot of beauty to them. And that's the unfortunate part.
But when it eventually dies, you can replace it with something wonderful, something similar in form. I like ninebark. It comes in multiple different colors. It's a native shrub. It has wonderful flowers that the pollinators and hummingbirds love. And it's a really good answer to replace something that might not necessarily be what people want.
Q: What are some trees that Michiganders should be planting, either some native or just non-invasive species that we can enjoy in good conscience?
A: We've been working with our partners with the other Midwest states, and we've been voting on what species we really, really like. And the common theme has been one of my favorite trees, Kentucky coffeetree. It's very resistant to disease and insects. It's one of the most salt-tolerant trees. So if you're salting on a snowy, icy day it can handle that runoff compared to a lot of our species. And it is just a really wonderful shade tree with strong wood. The only problem it has is during the winter. It looks so sad and barren without leaves, and people don't like it. But outside of that, I think it's one of the best trees you could plant.
There’s also bald cypress. We've seen those in Chicago at the Navy Pier, there's a bunch planted there. It's unique. It's a deciduous conifer. And people have been really embracing that one. And it's great for flooded areas or wetland areas that we have a lot of here in Michigan. And it's seen as a climate adaptable species as well.
