About Invasive Plants

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What are Invasive Plants?

Invasive species are non-native plants and animals which have been introduced to an area outside their native habitat. Many non-native plants were brought to the US deliberately, often as ornamental plants. Autumn olive, buckthorn, honeysuckle, multiflora rose, and Asian bittersweet vines were transported to the US by the horticultural industry and many were promoted as wildlife food; many of these plants are still being sold by local plant nurseries. Garlic mustard was brought here by colonists as a food crop. Some non-native plants were transported accidentally. For example, phragmites is believed to have been transported to the US accidentally as packing material and part of the ballast dumped on the east coast by ships.

Some of these non-native species subsequently become invasive, for many reasons. Often the insects, fungi, and herbivores that kept the species in check within its native landscape do not exist in the area where the species was introduced. Some plants are allelopathic; they secrete chemicals which inhibit growth of other plants or beneficial root fungi (mycorrhizal fungi). Many invasive plants have competitive advantages over native plants, by leafing out earlier in the spring and retaining their leaves later in the fall.

Without the natural competitors found in their native habitats, invasive plants grow unchecked, and may create monocultures which exclude our native plants. This changes ecological relationships in our native ecosystems and can harm ecosystem health, reduce the diversity of our native plants and wildlife, damage ecosystem services such as flood control, increase liabilities such as fire and flooding, and reduce property values.

OC CISMA Knotweed Brochure: Download PDF

OC CISMA Swallow-wort Brochure: Download PDF

Click to see the MIPN Brochure - "Why Should I Care About Invasive Plants?"

What is Phragmites?

OC CISMA Phragmites Brochure: Download PDF

Phragmites australis, the common reed, a non-native invasive plant brought here from Europe, is threatening our property values and environment.

The phragmites found in Oakland County is an invasive alien plant. Without the natural competitors in its native habitat, it is growing unchecked. Phragmites grow in roadside drainage ditches, lake shores, and other wetlands to a height of 10-15 feet. Phragmites crowd out cattails and other native wetland plants, harming our wildlife by crowding out the native plants they depend on for food and shelter.

The dry stalks of phragmites are highly flammable. This photo from the Oakland Press shows the phragmites fire at Great Lakes Crossing on March 2012. In March 2011, 160 acres of phragmites burned at Great Lakes Crossing Mall; smoke and fire were so intense that I-75 was closed and homes and businesses were evacuated.

On April 4, 2013, a phragmites fire on Harsens Island burned 150 acres. The heat was so intense it was burning the equipment used by the firefighters. The fire chief reported that phragmites fires burn very hot, at temperatures up to 2000 degrees, and generate their own wind. The firefighters kept the phragmites fire away from nearby houses because vinyl siding and windows on a home less than 500 feet from the fire could melt. Phragmites is aggressively filling in our wetlands, road side ditches and anywhere its rhizomes and seeds take hold. This plant can dry up wetlands and clog drainage ways, requiring expensive maintenance and repair. Phragmites harms our wetlands by choking out the cattails and other native plants which wildlife need for food and shelter, reducing our biodiversity, harming ecosystems, and lowering property values.

The Beaver Island Association created a video explaining how and why they decided to control the phragmites on their island. You can watch the video here.