Invasive Plants
Purple loosestrife (Lythrum salicaria)
Purple loosestrife is a perennial herb with seeds that are mostly wind dispersed, but they can be transported by animals. Seeds float and are also dispersed by water. Plants can spread by underground roots and shoots, as well as by seed. It occurs in wetland areas including cattail marshes, sedge meadows, and open bogs. Once established, purple loosestrife displaces native vegetation through rapid growth and heavy seed production. Dense stands can change drainage patterns by restricting the flow of water. Wildlife can be affected by the displacement of indigenous food items such as cattails and pondweed.
Common reed (Phragmites australis)
Common reed, or Phragmites, is a tall, perennial grass that can grow to over 15 feet in height. Phragmites forms dense stands which include both live stems and standing dead stems from previous year’s growth. Phragmites forms a dense network of roots and rhizomes which can go down several feet in depth. This pervasive species quickly invades sites taking over wetland communities and alters hydrology and habitat by blocking light to native plants and occupies the belowground growing space.
Reed canary grass (Phalaris arundinacea)
Reed canary grass is an aggressive, cool-season perennial grass that invades and dominates a variety of wetland types including marshes, wet prairies, sedge meadows, fens, stream banks, and seasonally wet areas. This species can also grow in disturbed areas and spoil piles. Roots spread extensively by creeping rhizomes and runners. Reed canary grass is difficult to eradicate and is one of the first wetland plants to emerge in the spring, enabling it to shade out native species that emerge later in the growing season.
Japanese stiltgrass (Microstegium vimineum)
Japanese stiltgrass is an annual grass, found in a range of habitats, from wetlands to early successional fields and forested uplands. Japanese stiltgrass alters light and moisture regimes and likely affects seed germination. The most effective control method is to prevent its spread into natural plant communities by avoiding disturbance to the vegetation and soils of these areas.
Mile-a-minute (Persicaria perfoliata)
Mile-a-minute (Persicaria perfoliata) is a trailing vine with barbed stems and triangular leaves. In contrast to other invasive vines, mile-a-minute is an herbaceous annual, meaning it dies each fall and new plants grow from germinating seeds in the spring. Each vine can grow 20 to 30 feet long, forming a dense, tangled blanket of intertwined vines. In the peak growing season, mile-a-minute can put on up to 6 inches of growth a day. Its leaves are distinctly triangular or arrowhead-shaped, 1 to 3 inches wide, vibrant green, and bear many hooked barbs along the underside of the central vein and leaf stem. The dense foliage of this invasive weed blankets and slowly suffocates native vegetation, making it extremely destructive and persistent despite being an annual plant.
Small carpetgrass (Arthraxon hispidus)
Small carpetgrass is also known as hairy joint and/or joint head grass. It is a low-growing, sprawling annual grass. Small carpet grass grows up to one and a half feet in height. Stems root at nodes and have bright green clasping leaves which are often sparsely hairy on the margins. This grass grows in wet areas such as stream banks, shorelines, flood plains and wet meadows. It prefers sunny, moist areas.
Multiflora rose (Rosa multiflora)
Multiflora rose is a thorny, perennial shrub with arching stems (canes), and leaves divided into five to eleven sharply toothed leaflets. The base of each leaf stalk bears a pair of fringed bracts. Beginning in May or June, clusters of showy, fragrant, white to pink flowers appear, each about an inch across. Small bright red fruits, or rose hips, develop during the summer, becoming leathery, and remain on the plant through the winter. Multiflora rose is extremely prolific and can form impenetrable thickets that exclude native plant species. This exotic rose readily invades open woodlands, forest edges, successional fields, savannas and prairies that have been subjected to land disturbance.
Glossy buckthorn (Frangula alnus)
Glossy buckthorn is a single stem or at times, multiple stem shrub or small tree that can grow up to approximately 20 feet. Leaves are glossy or shiny on top and have a dull green underside. Leaves are also alternate along branches, entire (smooth edges) to obscurely crenulate (leaf edges have small, rounded teeth). Glossy buckthorn is shade-tolerant. However, it frequently invades sunny spots which is why it is seen growing in open fields, along field edges, along roads and paths, and any other areas that are sunny. Photo credit: Elizabeth J. Czarapata, Wisconsin Department of Natural Resources
