In the early 1800s, seeds from the purple loosestrife made their way to the upper Atlantic coast of North America via the ballasts of European sailing vessels. The beautiful purple-flowered weed honed in on the region's thriving wetlands and began to take root as an unwelcome guest -- a predator rather than an adaptor. It spread across the country, overwhelming and suffocating the delicately balanced ecosystem of marshes, clogging waterways, strangling native vegetation and displacing wildlife.