Invasive Watchlist

by Elizabeth Monarch

When invasive species become established in a watershed, they often displace many of the native plants, cause property damage and cost thousands of dollars to eradicate. Here are three of the biggest offenders in the Lake Michigan watershed.

Japanese Barberry

japanese barberry berries are an invasive plant species in MichiganJapanese barberry is a spiny shrub with smooth-edged oval leaves that turn a beautiful, deep purple in the fall with bright red berries. It has long arching stems with needle-like spines at the leaf nodes and drooping small yellow flowers. Originally brought over from Japan in the 1800s to be used as an ornamental, Japanese barberry has escaped into the surrounding landscape. Despite its prickly charms, it has become an invasive species with a thorny disposition.

Found in a wide variety of environments, it can be along stream banks, old fields, and forests. It forms dense thickets up to 5 feet tall that shade and crowd out native plants. Not only does it alter the landscape, it also has been linked to increases in Lyme Disease-carrying ticks. The dense leaves and arching branches increase the humidity under it, perfect for tick nymphs, while providing habitat for mice, one of their hosts. Areas that have minimal Japanese barberry have been found to have significantly fewer ticks than areas with high densities of the invasive. It also alters the surrounding soil providing a habitat for non-native earthworms, which effect nutrients in soils needed by native plants.



Phragmites is an invasive plant species found in Michigan near the Muskegon River watershedFound in the United States in the early 1900s and found in Michigan in 1979, Phragmites is now distributed throughout the entire U.S. and most of Canada. A tall grass that quickly crowds out native species, it forms dense stands in wet areas such as river banks, marshes and ditch lines. Up to 20 feet tall, it crowds and shades out native plants such as cattails and makes it difficult for wildlife to use as habitat or a food source. The plant spreads primarily by its extensive root system and infestations have been measured to expand by as much as six feet per year via root spread.

The landscape of downstate Michigan waterfront property is heavily impacted by Phragmites where it completely blocks views as well as access to fishing and other water recreation sites.  It also destroys the curb appeal of homes behind it where it has filled the ditch lines. This is particularly noticeable in the down river areas surrounding Detroit and in the Saginaw Bay area. Fighting the Phragmites spread in Lower Michigan can be expensive and various organizations and governmental bodies are spending vast amounts of money.  In the Bay City Recreation Area alone from 2012 to 2016, it has cost over $125,000 to treat the shoreline. Fighting this invasive is challenging because most disturbances such as pulling or cutting stimulate plant growth and any root fragments left behind can grow into a whole new plant. Further complicating matters, there is also a native variety that looks very similar to the invasive.


Japanese Knotweed

Japanese Knotweed found near the Muskegon River in MichiganA large green shrub with thick stalks, Japanese knotweed grows fast and resembles bamboo with sprays of white flowers and large leaves. First introduced from Asia in the late 1800s, Japanese knotweed had been used for erosion control, windbreaks, fencerows and decorative landscaping projects. Japanese knotweed negatively impacts native ecosystems and landscape by forming very dense thickets that push out native plants. In riparian areas, it can survive severe floods and due to its virulent nature, Japanese knotweed quickly colonizes the scoured banks and islands.

In developed areas, it has been known to grow through pavement, sometimes resulting in damage to building foundations and roads. It is a tricky invasive to treat as any portion of the plant that touches the ground before it is completely dry is apt to root and start a new infestation. The plant is easily spread through contaminated fill dirt where it grows readily from root fragments (called rhizomes) and seeds. Due to recognition of Japanese knotweed as a severe threat to infrastructure and property values, the State of Michigan has made it illegal to purposely propagate or distribute this plant in the state.


The State of Michigan is broken into Cooperative Invasive Species Management Areas (CISMA) that will happily assist you with identification and determining treatment options for removal of invasive species from your locale. Visit Michigan Invasives Species Coalition at to find your county’s CISMA and contact information.


 Elizabeth Monarch - MRWA Guest ContributorAbout the Author: Elizabeth Monarch

Elizabeth graduated from Ohio State University with a Master’s degree in Ecological Restoration. She has worked on several different projects over her career. Various projects have included collecting data on invasive and rare plant species in the Huron-Manistee National Forest, tracking the spread of Emerald Ash Borer in central Ohio, and working with lampreys, pollution, and fish in the Great Lakes region.