Aster family (Asteraceae)
Description: This herbaceous perennial plant is 2–3½' tall, branching occasionally in the upper half. It is more or less erect, although the weight of the inflorescence often causes the entire plant to lean sideways. The slender stems are light green, terete, and either glabrous, sparsely pubescent, or hairy in lines. The alternate leaves are up to 6" long and 2" across, becoming gradually smaller as they ascend the stems. The petioles are very slender and about 1" long on the lower leaves, while the upper leaves are nearly sessile. The petioles are light green and often hairy. The lower to middle leaves are lanceolate-ovate with indented bases, while the upper leaves are lanceolate with rounded bases. All leaves taper gradually into slender acute tips, while their margins are smooth and often slightly ciliate. The upper leaf surface is medium green and glabrous (or nearly so), while the lower leaf surface is light green and either sparsely pubescent, hairy along the central vein, or glabrous. The lower leaf surface also has a reticulated network of fine secondary veins. The central stem (and any upper lateral stems) terminates in a panicle of flowerheads up to 1½' long and ¾' across.
Each flowerhead is about ¾–1" across, consisting of 10-20 ray florets that surround a similar number of disk florets. The petaloid rays of these flowerheads are lavender or pale blue-violet (rarely white), and they are individually linear-oblong in shape. The corollas of the disk florets are short-tubular with 5 minute lobes at their apices. Initially, these corollas are yellow, but they become reddish purple with age. On unusual specimens, these corollas are light pink to nearly white. At the base of each flowerhead, the overlapping phyllaries (scaly floral bracts) are linear-lanceolate and glabrous to finely pubescent. Depending on the stage of their maturity, the phyllaries have patches of dark green that are diamond-shaped near their tips, or they have central veins that are dark green. Otherwise, the phyllaries are light green. The blooming period occurs from late summer through the fall, lasting about 1–1½ months. Both the ray and disk florets can produce fertile achenes. These achenes are 2-3 mm. long and oblongoid in shape; they have small tufts of light brown hair at their apices. As a result, the achenes are distributed primarily by the wind. The root system is fibrous and rhizomatous; older plants sometimes develop a small caudex. Clonal colonies of plants can develop from the rhizomes.
Cultivation: The preference is partial sun, mesic to dry-mesic conditions, and soil that contains loam or some rocky material with decaying organic matter. Calcareous ground with a higher than normal pH is tolerated. Like many other asters (Symphyotrichum spp.), the foliage can be attacked by many kinds of insects and disease organisms. The plants have a tendency to flop over while in bloom.
Range & Habitat: The native Short's Aster is a fairly common species that occurs in the majority of counties in Illinois. However, it is less common in some southern areas of the state (see Distribution Map). Habitats include mesic to upland woodlands, rocky open woodlands and slopes, limestone bluffs, woodland borders, and areas along woodland paths. Short's Aster occurs in both oak-hickory woodlands and maple-basswood woodlands. This aster often occurs in areas where limestone is close to the surface of the ground; it is usually found in higher quality natural areas. Wildfires and other kinds of disturbance can be beneficial if they reduce excessive shade from overhead canopy trees, or they reduce competition from invasive shrubs.
Faunal Associations: The flowerheads of asters (Symphyotrichum spp.) attract many kinds of insects, especially long-tongued bees, small-tongued bees, butterflies, skippers, and flies. These insects obtain nectar or pollen from the flowerheads. Some bees are specialist pollinators of asters and sometimes goldenrods (Solidago spp.); these species include the plasterer bee Colletes simulans armata, and such Andrenid bees as Andrena asteris, Andrena asteroides, Andrena hirticincta, Andrena nubecula, Andrena simplex, and Andrena solidaginis. The caterpillars of two butterflies, Chlosyne nycteis (Silvery Checkerspot) and Phyciodes tharos (Pearl Crescent), feed on the foliage of asters. In addition, the caterpillars of such moths as Cucullia asteroides (The Asteroid), Carmenta corni (Aster Borer Moth), and many others feed on various parts of asters (see Moth Table). Other insect feeders include Exema canadensis and other leaf beetles, larvae of Calycomyza humeralis (Aster Leafminer Fly), larvae of several fruit flies, many aphids (especially Uroleucon spp.), Macrosteles fascifrons (Aster Leafhopper), the plant bug Plagiognathus cuneatus, and Corythucha marmorata (Goldenrod Lace Bug). Among birds, the Wild Turkey and Ruffed Grouse occasionally eat the seeds and foliage of these plants in woodland areas. Among mammals, both the White-tailed Deer and Cottontail Rabbit undoubtedly feed on the rather smooth foliage of Short's Aster and similar asters.
Photographic Location: A woodland edge near Busey Woods in Urbana, Illinois.
Comments: This is one of the more attractive woodland asters with flowers that are larger than average in size. Short's Aster (Symphyotrichum shortii) can be distinguished from other asters (Symphyotrichum spp.) by carefully considering the appearance of the foliage and flowerheads. The lower to middle leaves of Short's Aster are indented at the base with narrow petioles. Some asters, such as Symphyotrichum sagittifolium (Arrow-Leaved Aster), have winged petioles on their lower to middle leaves, while other asters have rounded or wedge-shaped bases on their lower to middle leaves. The margins of leaves in Short's Aster are devoid of teeth (or nearly so), while other woodland asters, such as Symphyotrichum cordifolium (Blue Wood Aster), have leaf margins with conspicuous teeth. Similarly, the upper leaf surface in Short's Aster is hairless (or nearly so), while the upper leaf surface of Symphyotrichum drummondii (Drummond's Aster) is pubescent. Finally, the flowerheads of Short's Aster are usually ¾" across or more, while the flowerheads of other woodland asters are usually less than ¾" across. A scientific synonym of this species is Aster shortii.