A Weed by Any Other Name
A young woman named Juliet once asked, “What’s in a name? A rose by any other name would smell as sweet.” It’s a fine question if you’re dreaming of Romeo Montague. But what if the rose is a non-native invasive plant?
“Multiflora rose is an aggressive, stubborn landscape invader with recurved thorns along the green stems,” says Rose Hiskes, a diagnostician at the Connecticut Agricultural Experiment Station and co-chair of the Connecticut Invasive Plants Working Group (CIPWG). “And it’s a state-listed invasive plant.”
Multiflora rose is only one among nearly 100 plants labeled by the state’s Invasive Plants Council because it creates environmental and economic damage. Rugosa rose is another.
People imported many of the listed invasive plants for their beauty (or their scent) from other continents. Others were imported for medicinal properties or farming purposes. Some, such as rugosa rose, remain in commercial trade. Other examples still legal for sale in the state include Norway maple, porcelainberry, Japanese barberry, water hyacinth, burning bush, creeping Jenny, and even the notorious mugwort. Even if they are banned from commerce in Connecticut, many are easily purchased on the Internet. One example is dame’s rocket.
Why are listed plants still sold? The science of weeds, it turns out, is complex. The answers are nuanced, and, some would say, influenced by commercial interests.
Bottom line: Though they may look like pretty roses at the garden center, invasive plants do not “smell as sweet” when they take over entire landscapes and refuse to leave. It’s worth your while to identify and manage invasive plants.
Unloved Native Plants
Yet, there’s a puzzle.
For simplicity’s sake, most of us label plants as weeds because we find them inconvenient, aggressive, or unattractive. They make us sneeze or itch, or they interfere with a tidy garden bed or a carpet of lawn. As a result of this simplified view, valuable native plants sometimes receive harsh treatment.
“There are many aggressive native plants that homeowners and groundskeepers find troublesome,” says Rose Hiskes. “Among those are several that become particularly noticeable in August and September, such as goldenrod, common milkweed, and Virginia creeper. People label them weeds, but they have important ecological roles. It’s helpful to wildlife if you can find a way to live with small populations of these plants.”
Goldenrod, for instance, has been called by some botanists the single most valuable native perennial plant for bees, butterflies, and moths. According to National Wildlife Federations’ Native Plant Finder (www.nwf.org/NativePlantFinder), more than 120 species of butterflies and moths use goldenrods as host plants for their larvae in our shoreline zip codes alone.
Note to allergy sufferers: Insects pollinate goldenrod; the plant’s pollen is not windborne. Unfortunately, another native plant, ragweed, is wind-pollinated and blossoms simultaneously as goldenrod.
And then there is the inconvenient truth about poison ivy. Though it strikes fear in our hearts, this native plant is valuable winter food for the black-capped chickadee, downy woodpecker, and 50 other regional birds—see the Menunkatuck Audubon Society’s article menunkatuck.org/winter-birds-love-poison-ivy.
Other unloved natives include violets, hay-scented fern, sassafras, sumacs, and mosses.
Cut Back Invasives in August, September
The Connecticut Invasive Plant Working Group offers a treasure chest of resources. For instance, the Invasive Plant Management Calendar is an easy-to-read guide to managing the top 10 species of concern to 2016 CIPWG Symposium attendees. Download it from cipwg.uconn.edu.
The chart with this story shows the all-important element of timing in invasive plant removal. A quick glance reveals that August and September are the best time of the year for cutting Japanese knotweed and oriental bittersweet. It is a good time to pull the seedlings of bittersweet, barberry, and garlic mustard. It is also time to mow or cut down multiflora rose, phragmites, and mugwort.
Indeed, cut and mow all the invasive plants you can find during August and September—you will probably prevent the plants from distributing seeds. For instance, garlic mustard is a biennial plant that sets its seeds in late summer of its second year. You can set back Japanese stiltgrass by mowing during the first two weeks of September, eliminating the formation of seed heads.
Avoiding Landscape Fatigue
I’ve noticed that many of us, myself included, reach a period of “landscape fatigue” at this time of year.
As summer ages into fall, we all too often focus on the perplexing quantity of green plants—wanted and unwanted—that have overgrown the spaces we envisioned for them. Avoid the temptation to give up. And when you’re shopping for plants, keep in mind that an invasive plant by any other name is still an invasive plant.
Here are some helpful resources that will help you “get into the weeds” with this timely topic of identify and managing invasive plants:
• State-Listed Invasive Plant Species: cipwg.uconn.edu/invasive_plant_list
• Invasive plant legislation: cipwg.uconn.edu/ct-state-invasive-plant-laws
Weed Identification Resources and Apps
• USDA National Invasive Species Information Center: www.invasivespeciesinfo.gov
• PictureThis: www.picturethisai.com Based on artificial intelligence, it offers about 85 percent accuracy.
• iNaturalist: www.inaturalist.org/observations/identify. This offers crowd-sourced plant identification, including invasive plants, as well as animal and insect identification.
Books about weeds:
• Weeds of the Northeast, by Uva, Neal, and DiTomaso. “The first comprehensive weed identification manual available for the Northeast, this book will facilitate appropriate weed management strategy in any horticultural or agronomic cropping system and will also serve home gardeners and landscape managers, as well as pest management specialists and allergists.”
• Eradicate Invasive Plants, by Terri Dunn Chace. “Teri Dunn Chace shows you how to recognize more than 200 common invasive plants and offers organic and responsible chemical eradication options for each species. With this reference on their shelves, gardeners, landscapers, and managers of public and private land across the country can confidently tackle the invasive plants to make room for a sustainable plant community.”
• Weed Control Methods for Use in Natural Areas, The Nature Conservancy. www.invasive.org/gist/handbook.html
• Mistaken Identity: Invasive Plants and their Native Look-Alikes, NRCS. www.nrcs.usda.gov
Kathy Connolly is a writer and speaker on landscape ecology, landscape design, and horticulture. Kathy@SpeakingofLandscapes.com.