Aster family (Asteraceae)
Description: This native perennial plant is 1-3' tall, branching occasionally. The stems are green or reddish brown, and have lines of white hairs. The alternate leaves are up to 5" long and ½" across, becoming much smaller as they ascend up the stems. They are narrowly lanceolate, oblanceolate, or elliptic, becoming linear near the compound flowers. There are usually a few teeth toward the tips of the larger leaves, otherwise they have smooth margins. A few hairs may be present along the major veins on the undersides of the leaves. The upper stems and some of the side stems have sizable panicles of compound flowers. Each compound flower has numerous small disk florets that are surrounded by about 8-12 white ray florets. The disk florets are initially pale yellow, but later become brown or reddish purple. A typical compound flower is about 1/3" across. A compound flower is subtended by small green bracts that are appressed together, or only slightly spreading. The blooming period occurs from late summer to the fall, and lasts about 1-2 months. There is little or no floral scent. The small achenes are slightly pubescent and have small tufts of white hair. They are distributed by the wind. Mature plants can develop a small caudex, with short rhizomes that facilitate vegetative reproduction. This plant occasionally forms colonies at favorable sites.
Cultivation: The preference is light shade to partial sun and moist conditions. Full sun is tolerated if the site is not too dry. Growth is best in rich organic soil, or a moisture retaining clay-loam. During dry weather, the lower leaves often wither away, and stressed out plants are vulnerable to many kinds of foliar disease.
Range & Habitat: Calico Aster occurs in most counties of Illinois, and is quite common (see Distribution Map). Habitats include moist meadows near woodlands and rivers, floodplain forests and flatwoods, seeps and swamps, semi-shaded sloughs near fields, and moist depressions in waste areas. This plant is primarily a woodland species, but it often strays into moist sunny areas nearby.
Faunal Associations: The flowers of this plant have shorter nectar tubes than many other species of asters, and they seem to attract a wide variety of insects, particularly in sunny areas. More common insect visitors include short-tongued bees, wasps, and flies, and less common visitors include long-tongued bees, small butterflies, skippers, beetles, and plant bugs. These insects seek nectar primarily, although the short-tongued bees may collect pollen, while some beetles and flies feed on the pollen. The caterpillars of Chlosyne nycteis (Silvery Checkerspot) and Phyciodes tharos (Pearl Crescent) feed on the foliage, as do the caterpillars of many kinds of moths (see Moth Table for aster species). The White-Tailed Deer and Cottontail Rabbit will browse on the foliage occasionally.
Photographic Location: The photographs were taken at the webmaster's wildflower garden in Urbana, Illinois.
Comments: This aster is more attractive in woodland areas, where it has a delicate appearance. It closely resembles such asters as Aster pilosus (Frost Aster), Aster ericoides (Heath Aster), and other species in the genus with small white flowers. The Calico Aster is a somewhat lanky plant with smaller compound flowers (about 1/3" across) and fewer ray florets per compound flower (about 10). In this regard, it is similar to the Heath Aster, but the latter species is a more compact plant with leaves that are shorter and more narrow than the Calico Aster. While the Heath Aster is often found in open prairies, the Calico Aster usually doesn't stray far from woodland and semi-shaded wetland areas. The common name refers to the diverse colors of the disk florets as they mature.