Every month, we will put a spotlight on an aquatic invasive species (AIS) in a re-occurring monthly article. Check it out! This month, we highlight a currently blooming ornamental plant – Purple loosestrife!

Purple Loosestrife

Purple loosestrife (Lythrum salicaria) is a wetland plant that was a popular ornamental due to its purple flowers. Native to Europe and Asia, purple loosestrife (PL) was both intentionally and accidentally introduced into the United States in the early 1800s. The plant was imported for decoration in gardens but soon escaped these gardens and started growing in wild places. At the same time as it was being imported intentionally, seeds were being brought over accidentally in soil used as solid cargo ship ballast.

With distinct purple flowers that grow on flower spikes, PL is easily noticeable when it is flowering. Each tiny flower has five or six petals around a yellow center. The plant blooms from early July to September. Leaves of the plant have smooth edges and grow to around 4 inches long. However, it is the stem of PL that is distinctive in identifying this plant. The stem is square-shaped and generally has four to six sides. The roots of PL can be quite extensive as each plant produces 30-50 root shoots. These roots tangle around other plant roots creating a dense root web. One of the challenges with trying to control PL is that the root structure makes physical removal difficult. In addition, new PL plants can grow from pieces of roots or stem fragments. However, PL primarily spreads by seeds. Every PL plant produces over 2.5 million seeds every year! These seeds are the same size as grains of sand and can easily be transported by wind, water, or hitching a ride on unsuspecting humans or wildlife. While seeds can germinate the following year, they are also able to lay dormant in soil for several years before successfully germinating. PL needs to be rooted in the soil but can tolerate a wide range of environmental conditions. It can grow in few feet of water such as in the ditch next to a road. It is most commonly seen along roadsides as ditches tend to provide a wet place to grow while still getting plenty of sunlight and few competing neighbor plants. PL can grow to be two to six feet tall.

Due to its ability to produce so many seeds that are easily transportable, the plant quickly spreads to new locations. With so many new plants, PL can oftentimes quickly out compete and replace native wetland plants that are more utilized by wetland animals for food, nesting sites, and cover. PL can quickly dominate a system and become the most common plant in a wetland. This can reduce habitat for wildlife as there are several cases of birds avoiding nesting sites in PL as well as fewer wildlife species in PL dominated wetlands. PL can also change the hydrology and nutrient availability in invaded wetlands. PL leaves are dropped in the fall and decompose but most native plants in wetlands decompose in the spring. This creates a change in when nutrients are released into the ecosystem that can change how the wetland functions. The dense growth of PL can also make accessing the open water difficult for boaters, swimmers, or hunters.

Purple loosestrife is classified as a Restricted species in all counties across Wisconsin.

Want to help? HELP PREVENT THE SPREAD!

Every time you come off the water, make sure to follow these steps to stop the spread of faucet snails and other aquatic invasive species:

* Inspect boats, trailers, push poles, anchors, and other equipment for attached aquatic plants or animals.

* Remove all attached plants or animals

* Drain all water from boats, motors, livewells and other equipment

* Never move live fish away from a waterbody

* Never release aquarium plants or animals into your local waterways

Follow the Fox Wolf Watershed Alliance’s Winnebago Waterways Program on our Winnebago Waterways Facebook page or @WinnWaterways on Twitter! You can also sign-up for email updates at WinnebagoWaterways.org.

Questions? Comments? Contact Chris Acy, the AIS Coordinator for the Winnebago Waterways Program covering Fond du Lac, Calumet, and Winnebago Counties at (920) 460-3674 or chris@fwwa.org!

Winnebago Waterways is a Fox-Wolf Watershed Alliance program. The Fox-Wolf Watershed Alliance is an independent nonprofit organization that identifies and advocates effective policies and actions that protect, restore, and sustain water resources in the Fox-Wolf River Basin.

Photo Credit: Liz West, Paul Skawinski