Eupatorium coelestinum, commonly known as mist flower, blue mistflower, or hardy ageratum, is a perennial wildflower native to North America. The plant has a long blooming season and produces clusters of small, powder blue flowers that attract butterflies and other pollinators. Some synonyms for eupatorium coelestinum include Conoclinium coelestinum, Ageratina coelestina, and Eupatorium compositifolium. These synonyms refer to different scientific names for the same plant, but they all describe the characteristics of the mist flower. Whether you call it eupatorium coelestinum, hardy ageratum, or any of its other synonyms, this wildflower is a beautiful addition to any garden or landscape.