Calico Aster
Symphyotrichum lateriflorum
Aster family (Asteraceae)

Description: This is a perennial plant about 1-3' tall that branches occasionally, often leaning toward one side. The stems are light green or reddish brown, and they have lines of white hairs. The alternate leaves are up to 4½" long and ½" across, becoming much smaller as they ascend the stems. They are narrowly lanceolate, oblanceolate, or elliptic, becoming linear near the flowerheads. There are usually a few teeth toward the tips of the larger leaves, otherwise they have smooth margins. Some hairs may be present along the major veins on the undersides of the leaves. The upper leaf surface is medium green, while the lower leaf surface is light green. The upper stems and some of the side stems produce panicles of flowerheads up to 10" long and 6" across. Each flowerhead has numerous small disk florets that are surrounded by about 8-12 ray florets. The corollas of the disk florets are initially pale yellow, but they later become brown or reddish purple; they are short-tubular in shape and 5-lobed. The petaloid rays are white and linear-oblong in shape. A typical flowerhead is about 1/3" (8 mm.) across. Each flowerhead is subtended by small green bracts (phyllaries) that are appressed together, or they are only slightly spreading.

The blooming period occurs from late summer to the fall, lasting about 1-2 months. There is little or no floral scent. The small achenes are slightly pubescent and they have small tufts of white hair. Distribution of the achenes is by wind. The root system is fibrous and rhizomatous; an older plant may develop a small caudex. Clonal offsets occasionally develop from the rhizomes. 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: The native Calico Aster occurs in most counties of Illinois, where it is native and quite common (see Distribution Map). Habitats include moist meadows near woodlands and rivers, floodplain forests and flatwoods, woodland borders, 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. It prefers areas with a history of disturbance.

Faunal Associations: The florets of Calico Aster (Symphyotrichum lateriflorum) have shorter nectar tubes than many other species of asters (Symphyotrichum spp.), and they seem to attract a wide variety of insects, particularly in sunny areas. Insects that have been observed to visit the flowerheads of this aster for nectar and/or pollen include honeybees, bumblebees, little carpenter bees (Ceratina spp.), leaf-cutting bees (Megachile spp.), Halictid bees (including green metallic bees), plasterer bees (Colletes spp.), masked bees (Hylaeus spp.), Andrenine bees, dagger bees (Heterosarus spp.), Crabronid wasps, Sphecid wasps, Vespid wasps, spider wasps (Pompilidae), Syrphid flies, Tachinid flies, Muscid flies, Calliphorid flies, butterflies, moths, beetles, and plant bugs (Robertson, 1929; Graenicher, 1909; Wilhelm & Rerciha, 2017). Other insects feed destructively on the foliage, sap, and other parts of asters. These species include leaf beetles, weevils, larvae of tumbling flower beetles, larvae of leaf-miner flies, larvae of gall flies, plant bugs, aphids, mealybugs, grasshoppers, katydids, larvae of twirler moths (Gelechiidae), larvae of Geometer moths, larvae of owlet moths (Noctuidae), larvae of Tortrix moths, and larvae of two butterflies, the Silvery Checkerspot (Chlosyne nycteis) and Pearl Crescent (Phyciodes tharos). See the Insect Table and Moth Table for more information about these species. Some vertebrate animals use asters as sources of food. The American Tree Sparrow and Ruffed Grouse feed on the seeds of these plants; the latter bird also feeds on the leaves. Some herbivorous mammals browse on the foliage of these plants, including Elk, White-tailed Deer, Cottontail Rabbit, and domesticated livestock (Martin et al., 1951/1961; Schneider et al., 2006; personal observations).

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 Symphyotrichum pilosum (Frost Aster), Symphyotrichum ericoides (Heath Aster), and other species in the genus with small white flowerheads. The Calico Aster (Symphyotrichum lateriflorum) is a somewhat lanky plant with smaller flowerheads (about 1/3" or 8 mm. across) and fewer ray florets per flowerhead (about 10) than many similar asters (Symphyotrichum spp.). 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 those of 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. Its common name refers to the diverse colors of the disk florets as they mature. Another common name of this species is the Side-Flowering Aster, and another scientific name is Aster lateriflorus.

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