[Wikipedia] Range, Habitat, Human Activity Impact: It is native to several regions of the northern hemisphere, including much of Eurasia and western North America. It is a plant of wetlands, particularly calcareous fens. It is common to abundant in many areas, but it is known to be negatively impacted by habitat fragmentation and other habitat destruction, and human activity has led to its extirpation from some areas where it was once common. (link added by Mary Ann Machi)