What is an invasive species?Invasive species are organisms that move to places where they are not native. They are aggressive and outcompete native species, causing harm to the ecosystem. In their homelands, natural predators limit the populations of these species. Many invasive species hitchhiked on items European settlers brought to North America. Plant seeds hid in bags of grain, ship ballast, and personal belongings. Gardeners, farmers, florists, and pharmacists brought other plants which became invasive, on purpose. Not all non-native species are invasive. Invasive plants tend to have hardy root systems, and some can produce millions of seeds per year. Invasive animals tend to be super adaptable. In their homelands, natural predators limit the populations of these species. North American animals tend not to feed on invasives because they are not used to them. Many people still introduce species noted for their 'hardiness', 'deep spreading roots,' or 'huge' seed crops. Below are several "successful" invasive species in the Lakeshore that are damaging ecosystems. . Terrestrial Plants
NPS Photo Baby’s Breath (Gypsophila paniculata)Florists brought baby’s breath to North America over a century ago for bouquets. During autumn, a baby’s breath bush breaks off at its base to roll like a tumbleweed. The wind blows them around and they drop seeds over a huge stretch of land. Its large taproot can go down 13 feet, which has allowed it to crowd out native plants like the threatened Pitcher's thistle. 
NPS photo/ M. Adams Spotted Knapweed (Centaurea stoebe)Although spotted knapweed has attractive pink flowers, it is harmful to native plants. The roots of spotted knapweed create an herbicide that prevents other plants from growing nearby. This reduces the habitat available to native plants. These chemicals can also irritate your skin so do not to pick it, or any other plant in the National Lakeshore. 
USDA Photo / M. Garland Autumn Olive (Elaeagnus umbellata)Farmers introduced this shrub to fight soil erosion, but it has spread everywhere. Autumn olive thrives in sensitive areas like grasslands and forest edges. They outcompete native vegetation for water, sunlight, and nutrients. The Lakeshore sometimes brings in goats to graze on invasive plants like autumn olive.
NPS Photo Purple Loosestrife (Lythrum salicaria)Purple loosestrife was brought from Europe to North America for gardening and beekeeping. This plant thrives in wetlands, but it can also be found along the road. A single plant sends up many flower stalks, which can produce over 3 million tiny seeds. Purple loosestrife outcompetes the native plants that animals need for food and shelter.
NPS Photo Garlic Mustard (Allaria petiolata)Europeans introduced garlic mustard for people to eat, but it has spread all over North America. It takes advantage of shady forest floors, creating thick stands that choke out native plants. They have reduced the biodiversity of many forests, and they can be toxic to native animals and insects. The pods of garlic mustard burst when disturbed, which sends their seeds flying. 
NPS Photo Common Burdock (Arctium minus)Many people may be familiar with burdock because its seed dispersal strategy was the inspiration for Velcro. The burred pods of the burdock plant allow its seeds to hitch a ride on animal fur and human clothing. The hooks of burdock seeds are so strong that they can prevent bats and birds from opening their wings once attached.
NPS Photo / D. Newman Black Locust (Robinia pseudoacacia)Farmers introduced black locust trees to the Upper Midwest for their rot-resistant wood. This tree establishes itself in disturbed areas, such as our rugged dune ecosystem. They multiply by sending up suckers from their roots or casting seeds everywhere. This can create dense stands that block the sunlight from reaching native plants on the ground. Aquatic Plants |
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Last updated: September 19, 2024