Purple Loosestrife (2 of 2) (image) Harvard University Share Print E-Mail Caption Purple loosestrife is one of the worst invasive plant species in the northeastern United States, and has exhibited a remarkably favorable response to climate change. It now flowers three weeks earlier since the time of Thoreau. In many wetland areas it has crowded out native vegetation and competes for local pollinators like this monarch butterfly in the area of Concord, Mass. Credit Abraham Miller-Rushing Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.