Mist Flower (Wild Ageratum; Blue Boneset)

Conoclinium coelestinum (formerly Eupatorium coelestinum)

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Photo of mist flower or wild ageratum plants with flowers
Mist flower, or wild ageratum, is a vigorous native perennial bearing fluffy-looking, bluish-purple flowerheads. It looks quite a bit like the annual ageratum that is sold as a bedding plant in garden centers.
Family

Asteraceae (Daisies)

Description

Mist flower, or wild ageratum, is a vigorous perennial bearing fluffy-looking, bluish-purple flowerheads. It often occurs in large stands. The flowerheads are in dense clusters (35–70 tiny florets per head), terminal or arising from the leaf axils, and blue or violet (rarely white). Blooms July–October. The leaves are opposite on short stems, ovate to triangular, with large teeth.

Similar species: The nonnative annual ageratum (Ageratum conyzoides) is sold as a bedding plant for flower gardens. That plant, however, is an annual with thin, fibrous roots, while mist flower is a vigorous perennial with a mass of interwoven rhizomes. Both are in the same tribe as bonesets, thoroughworts, and snakeroot.

Size

Height: normally 12–18 inches.

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Photo of mist flower in bloom
Purple Mist Flower
Mist flower, also called wild ageratum and blue boneset, gives pops of purple and lavender in late summer and early fall.

Mist Flower Wild Ageratum

A single stalk hosts a small spray of small fluffy purple flowers
A mist flower in Black Jack, MO
Habitat and conservation

Occurs in bottomland forests, swamps, banks of streams and rivers, margins of ponds and lakes, marshes and fens, ditches, gardens, railroads, roadsides, and shaded to open disturbed areas.

image of Mist Flower Wild Ageratum; Blue Boneset distribution map
Distribution in Missouri

Scattered, mostly south of the Missouri River.

Human connections

Under cultivation it spreads rapidly with an interwoven mass of roots and is highly aggressive. Cut back the plants during the summer to encourage a more compact growth habit before flowering begins in August. Where its spreading isn't a problem, it provides good color until the first frost.

Ecosystem connections

Butterflies, skippers, and bees are strongly attracted to the flowers. Other insects eat the foliage. Not many mammals eat this plant because of its bitter taste.