Just as leafy spurge looks harmless but is really an invasive species, purple loosestrife is another attractive-looking plant that can do more damage to the local environment. Purple loosestrife is a wetland invasive species that has taken over the river systems in Eastern Canada. While it looks like a beautiful flower, it is extremely aggressive and can wipe out cattails and other native flora. If its seeds spread, they can choke out wetlands. Purple loosestrife is native to Europe and Asia and was brought to North America in the early 19th century. It was likely introduced when its seeds were included in soil used as ballast in European sailing ships and discarded in North America.