The next time you consider buying a new plant, take a look in its pot to see if you might be taking home a bonus species.
Native hitchhiker plants can make wonderful additions to gardens or naturalized spaces. I’ve seen common boneset growing as a volunteer in potted goldenrods, and beautiful mosses and liverworts tagging along in other pots. These bonus species may take some extra water and nutrients away from the primary plant but are otherwise harmless and can help boost biodiversity free of charge!
Liverworts growing in a potted red maple sapling. Photo: Robyn Graygor.
Moss growing in an inkberry pot. Photo: Robyn Graygor.
However, other bonus plants that you may find growing in nursery pots can cause serious problems on residential and wild land.
Invasive plants are non-native species that spread aggressively and cause ecological or economic damage. They are often successful hitchhikers because they thrive in disturbance and can tolerate a variety of growing conditions.
Invasive hitchhikers can transform your land by overpowering other plants, changing species composition and altering the physical structure of vegetation. Knowing what to keep an eye out for while you are shopping for your next plant could help save you a big headache in the future.
While perusing nursery stock on the island, Natural Neighbors Program Director Rich Couse and I came across several plants for sale that had invasive hitchhikers tagging along for the ride. Read on to learn more about what we saw, how you can identify these invasive hitchhiker plants, and what you should do if you find one.
What Might Be Lurking in Your New Plant?
Mugwort
Mugwort growing out of a root ball of an ornamental shrub that is for sale. Photo: Robyn Graygor.
Mugwort (Artemisia vulgaris) seems to be one of the most common invasive plants found growing in plant pots. This perennial herb is famously hard to manage, especially once it's well established. It primarily reproduces by vegetative expansion and human dispersal of root propagules. Plants can grow from root fragments as small as 2 cm!
Away from nurseries, it can also be found growing in lawns, agricultural land, waste areas, forest edges, meadows, and roadsides. When introduced, it spreads aggressively and can form mono-specific stands.
Mugwort is one of the most common invasive plants found on residential properties on Martha’s Vineyard. We recommend smothering it in place for one or more growing seasons using a tarp covered with a thick layer of woodships.
Mugwort growing alongside a Agastache plant that is for sale. Photo: Robyn Graygor.
Tree of Heaven
The host plant of the dreaded spotted lanternfly, tree of heaven (Ailanthus altissima) is one plant you don't want to bring home. Typically reaching between 30-50’, but potentially growing up to 90’, this fast-growing tree quickly forms groves that can transform any landscape into a single-species forest.
Tree of heaven was brought to the United States from China in 1751 as an ornamental plant and became commercially available in the 1800s. It has been widely planted across cities and urban centers due to its fast growth, pollution resistance, and resilience.
After escaping cultivation, it can be found in a variety of habitats. It spreads both by seed and vegetative sprouting, and it alters soil chemistry, releasing allelopathic chemicals that discourage the growth of other species. When cut, the stump will aggressively resprout.
New trees can sprout from root suckers up to 27 meters away from the parent tree, and roots can damage sewer lines and building foundations.
Tree of heaven growing out of a Persimmon tree pot. Photo: Robyn Graygor.
Round-leaf Bittersweet
Round-leaf bittersweet growing out of an ornamental shrub pot. Photo: Robyn Graygor.
Round-leaf bittersweet (Celastrus orbiculatus) is the most common invasive plant found on Natural Neighbor visits. Known and hated by many, this woody vine was first brought to the United States from Asia in the 1860s to be used for ornamental purposes. You may recognize it from Christmas wreaths or decorative trellises.
Beyond festive holiday decorations, bittersweet has made a name for itself as one of the most successful invasive plants. It can climb up to 60 feet high and will strangle trees, forming a matrix of woody vines that smother vegetation. Its extensive root systems can extend over amazing distances, making it hard to pull up. If pieces of root are left behind, new plants will often resprout.
Persistent cutting may kill the plant, or at least help control its spread.
Multiflora Rose
Multiflora rose (Rosa multiflora) would make a dismal thorny surprise if you happened to take it home with a new plant. Introduced to the East Coast from Japan in the 1860s as a rootstock for ornamental roses, it then began being used for erosion control and for “living fences.”
New plants grow from seed or at the ends of mature plant's arching branches. The hooked thorns of multiflora rose are a pain to deal with, especially when this plant has grown into a dense, impenetrable thicket.
Individual plants can be cut or pulled with gloves, although resprouting will occur if root fragments are left behind. Mowing six or more times through the growing season for several years can be used to manage extensive stands.
Multiflora rose growing out of an ornamental shrub pot. Photo: Robyn Graygor.
Wineberry
Wineberry and mugwort growing out of an ornamental shrub pot. Photo: Robyn Graygor.
Although it produces delicious fruits, wineberry (Rubus phoenicolasius) is no better than any other invasive plant. Brought to the United States from Asia in the 1890s as breeding stock for raspberry cultivars, it has since escaped cultivation and begun growing in the wild.
Wineberry is an aggressive grower that can form thorny thickets across large areas. It spreads by seed, often carried by birds and mammals that have eaten the berries, although the fruits are not as nutritionally valuable to native wildlife as our native fruiting shrubs. It can also spread by underground rhizomes or at the end of an arching stem.
Plants can be pulled relatively easily in moist soil, though resprouting may occur. Mowing can be used in large stands to keep the plant from spreading via seed.
What to do if You Find an Invasive Plant in Nursery Stock
Hitchhikers
Unfortunately, it is not uncommon to come across invasive species in plant pots. There are many possible introduction pathways: soil may be contaminated with root fragments or seeds, nearby infestations might self-seed into nursery stock, or invasive plants that are still being sold may make their way into other plant pots.
If you see an invasive plant growing in another plant's pot, let the nursery staff know and express your concern. Do not buy the contaminated plant to avoid spreading the invasive plant to your property.
Invasive Plants For Sale
Many invasive plants have come to be so prolific because they were (or still are) distributed through horticultural trade.
As we have seen with the recent Chinese silvergrass (Miscanthus sinensis) ban, nursery stock that pre-exists the December 8, 2025, ban is allowed to be sold until December 31, 2026, as a phase-out period. As a result, when you go plant shopping you may still see Miscanthus or other recently banned invasive plants being sold.
We encourage you not to buy these plants with the intent to plant them. If you’re looking for a project, you could take on purchasing and safely disposing of invasive plants while they are in their phase-out period. More information on invasive plant disposal can be found here.
Use iNaturalist and GoBotany While Shopping
One of the best things you can do as a consumer is to educate yourself so you won’t accidentally bring an invasive plant home with you on your next plant shopping trip.
When I am searching for plants, I always make sure to read the plant tags and look up the Latin names in GoBotany to see if they are native to New England or not. If you are specifically going shopping for non-native ornamentals, I recommend doing thorough research to ensure you are not introducing any potentially problematic species.
As always, I encourage you to use iNaturalist. If you see a plant growing in a pot that doesn’t look like the picture on the tag, take a picture of it and use iNaturalist to help identify it. If there’s an invasive or non-native plant catching an unwelcomed ride, leave it behind and look for something else!
