People living at many latitudes in North America, Eurasia, and Australia are volunteering to help assess purple loosestrife (Lythrum salicaria) in their regions. The program is part of Dr. Beth Middleton's project to compare the role of purple loosestrife in its native and invasive habitats. Purple loosestrife is native to Eurasia but invaded northern North America after accidental introduction in the 1800s. This species may be reducing the value of infested wetlands for wildlife, although this claim is debated. The results of the study will help in efforts to control and predict the future spread of this species. Growing numbers of people are volunteering to help in Australia, Canada, Turkey, and the United States. The data measurements include documenting details about your site location, measuring the height and numbers of loosestrife, and making a few environmental observations.