Description: This native perennial plant is up to 3½' tall. An individual stem is sparsely branched and rather spindly in appearance, however mature plants often tiller at the base, sending up multiple stems that create a shrubby appearance. The stems are initially green with lines of small white hairs, but they often turn brown and become bare of leaves with age. The alternate leaves are up to 4" long and ½" wide near the base of the plant, but become much smaller as they ascend the flowering stems. They are linear or oblong, and have smooth margins. Tiny white hairs on the leaves provide a frost-like appearance, but this characteristic can vary considerably with the individual specimen or local ecotype.
The flowering stems are rather long with
conspicuous needle-like leaves, and they are held erect or horizontal to the
ground. The daisy-like compound flowers have numerous disk florets that are
yellow, later becoming reddish, which are surrounded by ray florets that are
white, rarely light pink or purple. There is no noticeable floral scent. Each
compound flower is about ½" across and has 16-35 ray florets. The
blooming period occurs during the fall for about 1½ months. The seeds
have small tufts of white or brownish hairs, which are distributed by the wind.
The root system is initially fibrous, but develops a caudex on mature
plants.
Cultivation: The preference
is full sun and mesic to dry conditions. This plant isn't particular about
soil, and can thrive in loam, clay, or gravelly material. Foliar disease rarely
bothers it, although some of the lower leaves may turn yellow and wither away
during a drought. The Frost Aster is easy to grow, but can spread aggressively
by re-seeding itself. 
Range &
Habitat: This common plant occurs in every county of Illinois (see
Distribution
Map). Typical habitats include disturbed areas of mesic to dry black soil
prairies, openings in upland forests, savannas, gravelly sandbars of lakes,
limestone glades, rocky cliffs and bluffs, pastures and abandoned fields, areas
along roadsides and railroads, and various kinds of waste ground. This is the
weediest species of Aster in Illinois. It often invades disturbed areas, where
it competes with many of the more common Eurasian weeds.
Faunal Associations: Like other asters, the flowers
of this plant attract many kinds of insects, including honeybees, bumblebees,
Halictine bees, Plasterer bees, Sphecid wasps, Paper wasps, Sand wasps, Spider
wasps, Syrphid flies, Tachinid flies, Blow flies, Muscid flies, Sulfur and
White butterflies. Because the Frost Aster is one of the last plants to remain
in flower before a heavy frost, it is an important source of pre-winter
nourishment for many of these insects. The caterpillars of the butterflies
Chlosyne nycteis (Silvery Checkerspot) and Phyciodes tharos
(Pearl Crescent) feed on the foliage. Also, the caterpillars of many
species of moths are known to feed on various parts of this and other asters
(see Moth Table). Various
insects suck juices from this plant, including aphids, lace bugs, and plant
bugs. Among the higher animals, the ecological value of this plant is low. The
Wild Turkey may nibble at both the leaves and seeds. The Cottontail Rabbit eats
the tender growth of young leaves and stems occasionally, while White-Tailed
Deer may browse on the entire plant to a limited extent.
Photographic Location: The upper and lower
photographs were taken at the webmaster's wildflower garden in Urbana,
Illinois, while the middle photograph was taken at Dave Monk's postage stamp
prairie in downtown Champaign, Illinois.
Comments: This plant can be quite attractive because it is often covered with small white flowers during the fall, helping to extend the season of bloom in wildflower gardens and elsewhere. People often pull it out of their flowerbeds without realizing what it is, and instead attempt to grow exotic flowers that wither away into nothing under the hot Midwestern sun, unless they receive constant water, fertilizer, and attention. The Frost Aster, on the other hand, flourishes without any special treatment. Distinguishing the different species of asters with small white flowers can be difficult. Each compound flower of the Frost Aster has more ray florets (usually well over 20) than those of similar species, such as Aster ericoides (Heath Aster). It is a more hairy plant than Aster lanceolatus (Panicled Aster).