For example, songbirds do not consume the small hard seed. Muskrats use cattails to build their homes, and they show a preference for cattail over purple loosestrife for food. Waterfowl, especially ducks, avoid wetlands that have become dominated with purple loosestrife. In addition, overall waterfowl production is decreased as suitable nesting habitat is eliminated. The plant's growth is generally too compact to offer cover, and cover may be as crucial to wildlife as food.
Purple loosestrife invades wetland areas and displaces native plants, such as cattails shown here.
When Lythrum reverts to the weedy purple loosestrife, it can invade wetlands and rapidly spread. Although purple loosestrife can be very aggressive, it does have good qualities in addition to landscaping uses. The flowers are a rich source of nectar and pollen for insects such as bees, adult parasitic wasps, and syrphid flies. Apiarists prize the plant because it is in flower for many weeks in mid-summer when few other suitable plants are flowering. Purple loosestrife has been heavily utilized in North Dakota flower gardens, park plantings, and golf courses.