Aster family (Asteraceae)
Description: This perennial plant is 1-2½' tall, branching occasionally to abundantly. The stems are light green, terete, and appressed-pubescent. The opposite leaves are up to 3" long and 2" across; they have short slender petioles. The leaf blades are oval-cordate, oval, or ovate in shape, while their margins are dentate or dentate-crenate. The upper blade surface is light green and glabrous with a conspicuous network of veins. The upper stems terminate in flat-topped clusters of flowerheads. Each cluster of flowerheads spans about 1-3" across. Each flowerhead has about 40-50 disk florets that are pink, lavender, or blue. Each floret has a tiny tubular corolla with 5 spreading lobes and a strongly exerted style that is divided into two filiform parts. Around the base of each flowerhead, there are several floral bracts (phyllaries) that are arranged in 1-2 series; they are light green and linear in shape. The branches underneath each flowerhead cluster are light green and terete.
The blooming period occurs from mid-summer to early autumn, lasting about 1-2 months. There is no noticeable floral scent. Afterwards, the florets are replaced by achenes with small tufts of hair; they are distributed by the wind. The root system is highly rhizomatous; this plant readily forms colonies.
Cultivation: The preference is full sun to light shade, moist conditions, and soil containing loam or silt. There should be sufficient organic material in the soil to retain moisture. This plant can spread aggressively in moist open ground, otherwise it presents few problems. Drought tolerance is poor. Propagation is by seed or division of the rhizomes.
Range & Distribution: The native Mistflower occurs in the southern half of Illinois and the Chicago area (see Distribution Map). It is fairly common in southern Illinois, but uncommon or absent elsewhere. This plant was introduced into the Chicago area. Some local populations in the wild are probably the result of seeds or plants that have escaped cultivation. Habitats include river-bottom prairies, moist open woodlands, gravelly seeps, borders of lakes and rivers, moist meadows in wooded areas, bases of bluffs, and ditches. This plant usually occurs in poorly drained areas and near sources of water.
Faunal Associations: The flowers attract long-tongued bees, butterflies, and skippers. Other occasional visitors include short-tongued bees, various flies, moths, and beetles. These insects seek nectar primarily, although the bees often collect pollen. Insects that feed on Eupatorium spp. (Bonesets) may also feed on Mistflower. Insect feeders of this group of plants include the caterpillars of such moths as Haploa clymene (Clymene Moth; eats foliage), Phragmatobia lineata (Lined Ruby Tiger Moth; eats foliage), Carmenta bassiformis (Eupatorium Borer Moth; bores into roots), and Schinia trifascia (Three-Lined Flower Moth; eats florets & developing seeds). Mammalian herbivores rarely consume Mistflower because of its bitter foliage.
Photographic Location: The photograph was taken along a drainage canal at Kaufman Lake Park in Champaign, Illinois.
Comments: Mistflower has attractive delicate flowers that are colored in pastel shades of pink, lavender, or blue. For this reason, it is often grown in flower gardens. This plant is closely related to the white-flowered Bonesets (Eupatorium spp.), and sometimes it is still referred to as Eupatorium coelestinum. Mistflower can be distinguished from the Bonesets primarily by its colorful flowers, relatively short stature, and broad opposite leaves that are heavily veined. While species of Joe-Pye Weed (Eupatoriadelphus spp.) have similar colorful flowers, they are taller plants with whorled leaves. All of these species are similar in that their flowerheads consist entirely of disk florets.