There are several invasive plant and tree species present in Mendota Heights. Invasive plant and tree species are species that are non-native, or alien to Minnesota that outcompete and inhibit native vegetative communities by taking away light, water, and nutrients that native species would normally receive. Invasive species can negatively affect our natural environment, economy, and sometimes the health of wildlife and people. These species often reproduce rapidly, and have no native insect or animal populations that consume them, leaving them free to spread uncontrollably.
The best way to control invasive species is to prevent the spread of new invasive species to un-infested areas. You can help prevent the spread of invasive species by:
- Ensuring belongings, clothing, tools, and supplies are free of dirt, mud, and plant debris before transporting them.
- Identifying and utilizing local sources of certified firewood and weed-free hay, compost, and mulch.
- Leaving unused firewood and plant material onsite or at home. Do not transport plant material or firewood!
If you believe you have an invasive plant or tree on your property, you may contact City Staff (contact information below), or a tree care or restoration professional for help in positively identifying invasive species and recommended control methods. The following are some of the common invasive plant and tree species that you may find on your property and options for removal and management. A full list of invasive species present in Minnesota can be accessed through the MN Department of Natural Resources website.
Early Detection Species: These are invasive species that are not present or have limited presence in Minnesota, but should be reported to the Minnesota Department of Agriculture in order to prevent their spread. Call “Arrest the Pest” at 651-201-6684 (metro) or 1-888-545-6684 (toll free) or email Monika Chandler, Weed Program, or call at 651-201-6537.
Common Invasive Species: The following are common invasive and/or noxious weed species found in Mendota Heights and Minnesota, and possible methods of control.
Special Note Regarding Herbicide Use: Always read the instructions included with your herbicide, and wear personal safety gear, such as gloves and eye protection. Never use herbicide near water, in windy conditions, or during or right before rain events.
Field bindweed (Convolvulus arvensis) is an invasive perennial in the morning glory family with an extensive rhizomatous and deep root system. It has alternate, arrowhead shaped leaves and simple trumpet-like white flowers. Bindweed has seeds that can remain viable in soil for several decades, and can invade gardens, prairies, and wet areas by growing rapidly and intertwining with, and chocking out, native species.
Buckthorn is an invasive, non-native understory tree, that is often pruned as a shrub or hedge, but can reach a height of up to 20 feet or greater. It was brought to North America from Europe in the early 1800s and has long-since escaped yards and invaded our native forests. It outcompetes its native counterparts by growing rapidly and leafing out early, as well as holding its leaves later into the fall. Buckthorn also produces a large amount of dark-colored berries that germinate quickly when spread by birds or after falling to the ground. Even though birds will eat the berries (usually as a last resort), they are not a good food source and can even make some birds and animals ill. There are two species of Buckthorn: Glossy Buckthorn (Frangula alnus) and Common or European (Rhamnus cathartica) Buckthorn. It can often be confused with the native Black Cherry tree, so identify carefully before removal. Fall is a great time for removal, as Buckthorn is easily identified by its green leaves well into late fall, when other native deciduous trees and plants have gone dormant. If you are unsure if you have buckthorn on your property, please contact City Staff (contact information at the bottom of this section) for a site visit and proper identification, or contact a tree care professional.
Controlling buckthorn takes a lot of tenacity and patience. Depending on the amount of buckthorn on your property, the control methods may vary. If you have a few trees, it is a much more achievable goal when planning to do the work yourself. If you have a large stand of buckthorn, it may be best to hire a tree care or native restoration company. In most cases, buckthorn removal and control is a multi-year process. If you do have more than a few trees, make a long-term plan. Remove plants that are fruit-producing first, as well as addressing areas with fewer concentrations before tackling heavily-invaded areas.
Canada thistle (Cirsium arvense) is an herbaceous perennial with thorns along the edges of its oblong leaves. Purple flowers bloom on the terminal branched stems beginning in June. It grows to 2 to 5 feet in height and possesses both a taproot and horizontal spreading roots that can form new plants. Canada thistle invades prairies, savannas, and disturbed areas. It generally likes dry soil, but can also spread into intermittently wet areas.
- Hand pulling or manual removal for small infestations
- Cutting prior to seed production combined with spot herbicide treatment
Common barberry (Berberis vulgaris) is a deciduous shrub native to Asia that invades several habitats, including woodland and prairie. It readily produces thousands of seeds per shrub with substantial longevity and a high germination rate. Common barberry can reach a height of approximately 8 to 10 feet and has 3-pronged spines or thorns that line its branches. It has pale yellow flowers, and blooms in May and June.
Minnesota Department of Agriculture
Common burdock (Arctium minus) Biennial plant that produces a basal rosette of large leaves in its first year, and a tall stalk with purples flowers and numerous hooked bracts that form burs. Burs stick easily to clothing and animal fur.
- Hand-pulling or mowing prior to flowering.
Garlic Mustard (Alliaria petiolate) is a biennial plant that grows to a height of 2-3 feet in its second year, with heart-shaped leaves and small clusters of white flowers that bloom in late spring. Garlic mustard gets its name from a strong garlic odor that is produced when the plant is crushed. It can invade wooded sites in both upland and wet areas, and outcompete native species rapidly. You can find it in shady wooded or landscaped areas throughout Minnesota.
Several species of Knapweed (Centaurea spp.) including Brown, Diffuse, Meadow, Russian, and spotted, are herbaceous perennials or biennials from Europe and Asia that invade dry native prairie, pastures, and disturbed areas. Most species have hoary branched stems and thistle-like pink or purple flowers at the terminal stem. Knapweed blooms from July through September and grows to an average height of 3 feet.
Leafy spurge (Euphorbia esula) is a perennial herbaceous plant with alternate, thin oblong leaves with small yellow-green bracted flower clusters that bloom in late May through fall. Seeds disperse explosively and have a high germination rate. This invasive rapidly invades disturbed areas, such as roadsides, and cropland, but can also quickly invade prairies and savanna areas. It is extremely hard to control once established.
Poison Hemlock (Conium maculatum) is a biennial plant that is highly poisonous when ingested, and can even be absorbed through skin contact. It has pinnately compound fern-like leaves, large clusters of small white flowers, and can grow to a height of 8 feet. It invades native wetland communities, stream banks, and roadsides.
MN Department of Natural Resources
Purple Loosestrife (Lythrum salicara L.) is a noxious weed native to Europe and Asia. It is a semi-aquatic perennial species that invades wetland areas by forming a dense carpet of bushy growth, approximately 4 to 7 feet in height, and produces thousands of tiny seeds that are easily dispersed. It has bright pink to purple spikes of small flowers at the top of each stem, blooming from July through September.
MN Department of Agriculture
Vetches (Fabaceae Family) are spreading, perennial herbaceous legumes with a strong root system. They have pinnately compound leaflets and purple/pink flowers. They spread quickly both by seed and rhizomes, and are highly adaptable to several soil types.
Wild parsnip (Pastinaca sativa) is a flowering perennial, native to Europe and Asia that reaches approximately 4 feet in height in the blooming stage, with alternate oval leaflets and a flat-topped cluster of yellow flowers. It blooms from June through late summer, and has a toxic sap that causes skin blisters when skin comes into contact with the plant and then is exposed to sunlight. The plant invades disturbed areas and spreads rapidly once established, posing a particular threat to native prairies.
- Hand pulling (make sure to wear protective clothing, including gloves, long sleeves, and long pants)