Conoclinium coelestinum, the blue mistflower, is a North American species of herbaceous perennial flowering plant in the sunflower family. It was formerly classified in the genus Eupatorium, but phylogenetic analyses in the late 20th century research indicated that that genus should be split, and the species was reclassified in Conoclinium.

Conoclinium coelestinum can reach a height of about 3 feet (0.91 m). It has opposite leaves, almost triangular-shaped. On the top this, the plant forms clusters of bright blue, violet or white flower heads, about 1/4 inch long. It flowers from July to November.

Blue mistflower is often grown as a garden plant, although it does have a tendency to spread and take over a garden. It is recommended for habitat restoration within its native range, especially in wet soils.