Three Least Wanted Plants

There are many invasive plants that can be found within the watershed, including some aquatic species. Many of these have been imported from other areas as ornamentals and escaped cultivation and others have been accidently transported from other areas. We’ll take a look at the 3 most prevalent invasive plants that are located within the watershed and what can be done to control them.



Purple Loosestrife - This species is an invasive plant that favors shoreline habitats, although it can be found in other areas such as road sides or in fields. In our community, purple loosestrife is mostly found in isolated spots along the lakeshore. This invasive plant is prolific, and will choke out native species of plants if allowed to grow unchecked. Many of the native plant species that could be affected are beneficial due to the fact that they help control erosion. Purple Loosestrife is poor in this respect. During late July and through August, it is easy to distinguish as purple flowers emerge. With isolated instances of this invasive plant are present, the easiest way to con-trol them is simply pull them out. If you pull them out, try to get the roots, if you don’t succeed with removing the roots, at least you will have removed the possibility of seeds spreading for the following season. (A small shovel may help) A week or so after the flowers are visible; seeds may start to form, so place the removed plants in a plastic bag to prevent seed spread.




Japanese Knotweed - Originally introduced as an ornamental plant, this invasive species has escaped cultivation to become a nuisance. Not only does it displace native species of plants, but if left growing near foundations and walkways, it can cause damage due to its extensive root structure penetrating cracks in masonry. Like purple loosestrife, it will prolifically grow and take over large sections of land, covering affected areas with thickets of broad, oval leaves. Although the rhizomes, or root system, are very extensive, Japanese knotweed is a poor plant for erosion/sedimentation holdback along lake shores and stream banks. A stand of Japanese knotweed can grow over 10 feet tall and be dense enough to appear impenetrable. Removal of this plant is best done by cutting near the base; at least 3 cuttings per growing season are necessary to suppress growth and spread. It is best not to try to pull knotweed out by the roots because, due to its extensive rhizome structure, some of the root system will be left to grow again. The cut stems should disposed of by bagging or burning. Do not dispose of them by placing them in a pile on the ground or a compost pit; they will likely take root and infest a new area.



Japanese Barberry - This is another ornamental that has escaped cultivation. It is known for its red berries and numerous sharp spines that can make a thicket impenetrable. The Japanese barberry is both sun and shade tolerant and can grow in a variety of soils. Once established, thickets of barberry can choke out native plant life. Birds eat the berries and thus transport this invasive to new areas. In thickets, the Japanese barberry can grow to a height of 6’ or more. Removal can be accomplished by pulling by the roots; gloves are advised due to the spines and a hoe or shovel will help. In areas where the roots are too well established, mowing or cutting can be used to control growth. The good news about these invasive species is that although present in the watershed, they have not completely overtaken native species in most areas. Many properties where invasive plants have been observed have isolated pock-ets that can be controlled by the methods outlined above. Keeping these inva-sive plants in check will help protect lakes and streams in the watershed from erosion problems and will be beneficial for habitat preservation and high water quality.