Flat-Topped Aster
Doellingeria umbellata
Aster family (Asteraceae)

Description: This perennial wildflower is 2-5' tall and usually unbranched, except where the inflorescence occurs. There are no basal leaves. The terete central stem is light green, purplish red, or yellowish brown; the typical variety is glabrous or sparsely short-pubescent, while var. pubens tends to be more pubescent. Alternate leaves occur along the entire length of the stem; they are ascending and slightly recurved. The lowermost leaves are small and scale-like, while the remaining leaves are 3-5" long, -1" across, and relatively uniform in size as they ascend the stem. The leaves are elliptic or lanceolate-elliptic in shape, smooth and short-ciliate along their margins, and either sessile or with short petioles. The upper leaf surface is medium to dark green, while the lower surface is pale green or whitish green. The upper and lower leaf surfaces of the typical variety are glabrous to sparsely short-pubescent. The upper leaf surface of var. pubens is sparsely to moderately short-pubescent or canescent, while the lower surface is moderately to densely short-pubescent or canescent.



The central stem terminates in a flat-headed panicle (compound corymb) of flowerheads about 3-12" across. Individual flowerheads are about " across, consisting of 5-12 ray florets that surround 12-25 disk florets. The petal-like corollas of the ray florets are white; the tubular corollas of the disk florets are yellow while in bloom, but become cream-colored or dingy white thereafter. Each disk floret has 5 spreading lobes. At the base of each flowerhead, there are 2-4 series of appressed floral bracts (phyllaries) that are narrowly oblong, green, and glabrous to short-pubescent. The branches of the inflorescence are light green or yellowish brown; they are either glabrous or short-pubescent. Leafy bracts about -1" long occur along these branches; they are lanceolate to narrowly elliptic. The blooming period occurs from late summer into the fall, lasting 1-2 months. Both ray and disk florets are replaced by achenes with whitish tufts of hair. In each tuft of hair, the outermost hairs are bristly and short (less than 1 mm. in length), while the inner hairs are longer (3-6 mm. in length). Individual achenes are about 3 mm. (1/8") long, bullet-shaped, and sparsely short-pubescent. They are distributed by the wind. The root system is fibrous and rhizomatous. Occasionally, small colonies are formed from vegetative offsets.

Cultivation: The preference is full or partial sun, slightly wet to moist conditions, and calcareous soil that contains sandy-loam. The pH should be slightly acidic. This wildflower can adapt to other kinds of soil, although they are not preferred.

Range & Habitat: The native Flat-Topped Aster is occasional in NE Illinois and parts of central Illinois, while in the rest of the state it is uncommon or absent. Habitats include wet to moist sand prairies, moist sandy thickets, soggy meadows and openings in wooded areas, interdunal sloughs and swales near Lake Michigan, fens, and seeps. This wildflower is found in higher quality wetlands that are often sandy and calcareous.

Faunal Associations: The nectar and pollen of the flowerheads attract long-tongued bees, short-tongued bees, wasps, flies, butterflies, beetles, and other insects. The foliage, plant juices, roots, and other parts of Flat-Topped Aster and other asters are eaten by many insects. The caterpillars of an uncommon butterfly, Chlosyne harrisii (Harris' Checkerspot), feed on Flat-Topped Aster specifically. Other insect feeders include caterpillars of the moths Acrocercops astericola, Astrotischeria astericola, and Carmenta corni (Aster Borer Moth); see the Moth Table for other moth species that feed on asters. Asters are also host plants of Macrosteles quadrilineatus (Aster Leafhopper), various aphids (primarily Uroleucon spp.), the plant bug Plagiognathus cuneatus, the lace bugs Corythucha marmorata and Galeatus spinifrons, the leaf beetles Microrhopala excavata and Exema canadensis, caterpillars of the butterflies Chlosyne nycteis (Silvery Checkerspot) and Phyciodes tharos (Pearl Crescent), larvae of Calycomyza humeralis (Aster Leafminer Fly), and larvae of small flies in the Tephritidae (Paroxyna albiceps, Tomoplagia obliqua, & Trupanea actinobola). Some vertebrate animals also feed on asters occasionally. The Ruffed Grouse and Wild Turkey feed on the seeds and foliage, while such songbirds as the Swamp Sparrow and Eastern Goldfinch also eat the seeds. The White-Tailed Deer and Cottontail Rabbit browse on the foliage; cattle, sheep, and other domesticated farm animals also browse on the foliage.

Photographic Location: A wet sand prairie at the Indiana Dunes National Lakeshore in NW Indiana.



Comments:
Flat-Topped Aster is an attractive wildflower that favors relatively open areas that are damp and sandy. Because of its flat-topped inflorescence, it is relatively easy to distinguish from other asters (Aster spp.) within the state. In particular, the prominent disk florets of the flowerheads are somewhat unusual in that they become dingy white or cream-colored shortly after they bloom, rather than orange-red or purple. The reason Flat-Topped Aster has been assigned to the Doellingeria genus is related to the different hair lengths of its tufted achenes: the outer hairs are less than 1 mm. in length, while the inner hairs are 3-6 mm. in length. Usually, asters have a uniform length for the hairs of their tufted achenes. An older scientific name of Flat-Topped Aster is Aster umbellatus.

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