[Wikipedia] Invasiveness: The major threat from Japanese hedge parsley is its ability to grow vigorously and disperse rapidly.[3] Japanese hedge parsley was first introduced to North America in 1917 and has been considered invasive since its introduction.[6] Reasons for its introduction are unknown, but it is assumed it was for medicinal purposes because it is not considered ornamental.[6] The plant's current distribution as an invasive species is in southern parts of Canada and in the Midwestern, Eastern, Southern parts of the US, and Oregon. (link added by Mary Ann Machi)