The battle of invasive plants, and two to watch out for

The invasive Autumn Olive is pictured in its foliage, flowering, and berry stages. This plant can be difficult to control because even after it is cut, stumps and roots will continue to re-sprout new shoots.

By Claire Pajka

The Manchester area is currently involved in an intense invasive battle. But what, exactly, are invasive plants? An invasive plant is considered any plant that is non-native to the area and has potential to seriously disrupt or harm the balance of natural communities. According to the Jackson Lenawee Washtenaw Cooperative Invasive Species Management Area (JLW CISMA), invasive plants may also cause harm to not only the environment, but the economy or human health as well.

Not all non-native plants are invasive, but non-native plants with aggressive traits – like rapid growth rate and an extended growing season – earn the title “invasive.” Invasive species can become dangerous to the balance in ecosystems because they lack natural predators, and can easily out-compete their native-plant neighbors.

But how did invasive plants get here in the first place? Some plants were specifically brought over by European settlers for agriculture; and though non-native, are not considered aggressive enough to be invasive. Some invasives were introduced by accident, such as the case of thistle seeds hitch-hiking on boats. However, many invasives were brought purposely from their native areas for ornamental landscaping – like multiflora rose and Japanese Knotweed – and those invasives still pose a large threat to natural ecosystems today.

By learning to identify two invasive plant species–Japanese Stiltgrass and Autumn Olive, highlighted below–Manchester residents will be able to keep the native plants and wildlife happy and safe in their home ecosystems.

Japanese Stiltgrass

Japanese stiltgrass – though native to China, Japan, Korea, Malaysia, and India – was discovered in nearby Scio Township in 2017. As this is the first appearance of the stiltgrass in Michigan, early detection and rapid response are key to stopping the spread of this invasive. Stiltgrass’ ability to release a huge amount of seeds that spread rapidly by water flow, foot and vehicular traffic, and wildlife makes it extremely difficult to control its spread, allowing it to easily outcompete native plants and disrupt ecosystem balance. Reaching 2-3 feet in height and
resembling thin bamboo, the leaves are pale green and lance-shaped. If left alone, it will create a
dense mat and choke out other plants on forest floors. Identification is key before mid to late August, as stiltgrass produces flower stalks and releases seeds during this time.

Japanese Stiltgrass flower collage

Because Japanese stiltgrass is relatively new to the area, it has a higher chance of being controlled and eliminated. Time is of the essence when reporting Japanese Stiltgrass, and the JLW CISMA website asks individuals who find it to email shikha.singh@macd.org with pictures. You can also report Japanese Stiltgrass here on the JLW CISMA website by providing photos of the invasive, as well as the date and time of the observation. The Midwest Invasive Species Information Network (MISIN) online or mobile reporting app, available online or on the app store, is another invasive reporting option. The Midwest Invasive Plant Network (MIPN) is also a good resource for learning about invasive management, and contains a database of different control techniques like manual weeding, and herbicides.

Autumn Olive

The Autumn Olive, native to Asia, is a deciduous shrub that can grow to be 20 feet tall. Not only is it highly aggressive in shading out desirable native plants, but it fixes nitrogen in the soil, degrading native plant communities that are adapted to grow in specific low-nutrient soils. Much like buckthorn, autumn olive is difficult to control because even after it is cut, stumps and roots will continue to re-sprout new shoots.

To identify autumn olive, look for large shrubs with oval shaped, pointed-tip leaves that have a shimmery silver underside. Creamy white or light yellow flowers bloom in August and September in Michigan, and red berries ripen in September and October. These berries are eaten by birds, which disperse the seeds and allow autumn olive to spread to vast areas. Buffaloberry is a native look alike, but autumn olive can be distinguished by its alternate leaves, shown below.

Alternate vs. opposite leaf patterns

If you think you’ve found autumn olive, you should report it on the MISIN website or mobile app, and can learn more about management and removal techniques – such as cutting, prescribed burning, and pesticide application – on the MIPN website.

Invasive plants don’t provide adequate food sources or habitat for native wildlife, and often don’t have benefits for native pollinators, either. By keeping an eye out for invasives, and reacting quickly if they find any, residents can help sustain and bring back native biodiversity to the ecosystems around them.

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by Marsha Chartrand

Marsha Johnson Chartrand, a founder, writer, and copy editor with the Manchester Mirror, is a 50-year resident of Manchester. She has a long history of volunteer and community involvement.