Missouri has 24 species of New World asters. They can be difficult to identify to species. Most bloom in late summer and fall. Most are perennial herbs growing from short, stout rhizomes, with 1 or a few upright stems. (Only two species are taprooted annuals, and these are introduced and rare to uncommon.) The flower clusters are usually relatively elongated (not appearing flat-topped). This page serves to introduce Missouri’s native asters as a group.
Depending on the species, the ray flowers of our native asters may be lavender, pink, bluish, or white. Although each species most commonly occurs in a particular color form, individual plants within each species may have an unusual color. For example, a typically bluish-flowering species may occasionally have individuals that bloom white, or vice versa. Also, both ray and disk flowers may change color as they mature and age. Thus the flower color is not as helpful as you might hope.
The yellow disk flowers at the center of the flowerheads typically turn reddish over time.
To identify the various species of New World asters, you must look at a variety of characters, including details of the basal, lower, and upper stem leaves; the hairiness of the plant and the types of hairs, if present; the shape, configuration, and other details of the involucral bracts (the leafy scales under the flowerheads); and the measurements of various plant parts. For accurate identification of individual species, we recommend volume 2 of Steyermark’s Flora of Missouri (Yatskievych, 2006). This web page is just an introduction.
Twenty-four species of New World asters in genus Symphyotrichum have been recorded for Missouri:
- Many-rayed (woodland) aster (S. anomalum). Scattered, mostly in the Ozarks and eastern half of northern Missouri, especially in glades, upland prairies and woodlands, and other dry, rocky areas. Involucral bracts are reflexed (bent backward), and the leaves are soft. Typically blooms purple to blue (rarely white), July–November.
- Rayless alkali aster (S. ciliatum). Native to western and northern states; introduced, collected in Missouri only once, along a railroad in Clay County. This species at first seems to have no petal-like ray florets, but actually there are several rows of them, with the petal portion of each poorly developed. This species is a taprooted annual. Typically blooms pink to pale purple, August–September.
- Blue wood aster (S. cordifolium). Scattered nearly statewide. Bottomland forests, rich upland forests, banks of streams and rivers, bases and ledges of bluffs. Typically blooms purplish blue to lavender, August–November.
- Drummond aster (S. drummondii). Scattered nearly statewide, in a wide variety of habitats. In wetter sites, it sometimes grows with blue wood aster (S. cordifolium), and in drier sites it sometimes occurs with white arrowleaf aster (S. urophyllum). It may hybridize with both, creating plants with intermediate characteristics. Typically blooms purplish blue to lavender, August–November.
- Rice button (bushy white) aster (S. dumosum). Uncommon, occurring mostly in southern Missouri; introduced in the city of St. Louis. Grows in fens, margins of sinkhole ponds, bottomland prairies, and other, usually moist place. Typically blooms white to pale pink or bluish-tinged, August–November.
- Wreath (white heath) aster (S. ericoides). Scattered to common in the Glaciated and Unglaciated Plains of northern and western Missouri; mostly absent elsewhere. Upland prairies, loess hill prairies, glades, rich upland forests. Often forms colonies. Low, leafy, bushy plant to 3 feet. Leaves pointed, small, to only 3 inches long and less than ¼ inch wide at base, these usually dropping off by bloom time; leaves are smaller toward the top of the plant. Flowerheads only to about ½ inch wide. Typically blooms white (rarely lavender to blue), July–October.
- White prairie aster (S. falcatum). Introduced; native to western North America. There are historic collections of this plant from Jackson County and the city of St. Louis. The natural range of this species approaches northwestern Missouri, and this plant may one day be discovered in the loess hill prairies in that region. Typically blooms white, July–October.
- Smooth (smooth blue) aster (S. laeve). Scattered nearly statewide, but apparently absent from the Bootheel lowlands. Upland prairies, loess hill prairies, glades, ledges and tops of bluffs, forest openings, and less commonly in bottomland prairies, fens, and pond and lake edges. The foliage is bluish green; the leaves smooth and nearly waxy, but with very rough margins. Stem leaves taper to a pointed tip, are widest at the base and strongly clasp the stem. Typically blooms lavender to purple to bluish purple, August–October.
- Tall white (panicled) aster (S. lanceolatum). Scattered nearly statewide, usually in moist or wet soils in a variety of low areas, but also in pastures, fencerows, ditches. Usually in dense colonies. A widespread, variable species with 4 recognized varieties; these might be confused with a number of other native asters. To 5 feet tall, often hairy, especially at the tops of the plant. Leaves narrow, to 6 inches long and 1½ inch wide; widest at middle. Typically blooms white (rarely pink, lavender, or bluish-tinged), August–October.
- White woodland aster (S. lateriflorum). Occurs nearly statewide, most common south of the Missouri River. Mostly occurs in wet areas: bottomland forests, rich upland forests, bases and ledges of bluffs, banks of streams, rivers, and spring branches, margins of ponds and lakes, sinkhole ponds, fens, sloughs, and moist depressions in prairies, plus pastures and gardens. This species can colonize and spread rapidly in disturbed sites, a characteristic that botanists often call “weediness.” Typically blooms white (rarely pinkish-tinged or light lavender), August–November.
- New England aster (S. novae-angliae). Scattered nearly statewide, but apparently absent from the Mississippi Lowlands and uncommon in parts of the northern and western Missouri plains. Bottomland prairies, moist places in upland prairies, fens, bases of bluffs, stream and river banks, margins of ponds and lakes, plus pastures, fencerows, and banks of ditches. Perhaps our most popular native aster in cultivation, and varieties with different growth forms and flower colors are available. A hairy plant to 6 feet tall, with clasping leaves to 4 inches long. Flower stalks and bracts are covered with gland-tipped hairs. Typically blooms reddish purple to purple (in cultivation, pink and white as well), July–October.
- Aromatic (oblong-leaved) aster (S. oblongifolium). Scattered, mostly south of the Missouri River, but extending northward locally mostly in counties along the Mississippi and Missouri rivers; apparently absent from the Bootheel lowlands. Look for it in dry, rocky places: glades, ledges and tops of bluffs, upland prairies, and openings of dry upland forests. A fragrant, hairy aster only growing to about 2 feet tall. Use a hand lens to see the small, round glands on the leaves and upper stems. Leaves clasping, lacking teeth. Involucral bracts reflexed (bent backward), covered with glands, the basal set leaflike. Numerous small, leaflike bracts on the flower stalks. Typically blooms reddish purple to bluish purple (rarely pink), July–November.
- Ontario aster (S. ontarionis). Scattered nearly statewide, most common in counties along the Missouri and Mississippi rivers; apparently absent from the Unglaciated Plains of northern Missouri. Bottomland forests, rich upland forests, swamps, sloughs, stream and river banks, margins of ponds and lakes, bases of bluffs, rarely on tops of bluffs and glades. Blooms white, August–October.
- Azure (sky blue) aster (blue devil) (S. oolentangiense; formerly Aster azureus). Scattered nearly statewide. Glades, upland prairies, sand prairies, upland forests on rocky slopes, ledges and tops of bluffs. There is complex variation within this species. Usually less than 3 feet tall. Basal leaves rough, with long stalks, blades heart-shaped at the base, with or without teeth. Stem leaves smaller the higher on the plant, not heart-shaped at the base, at the top of the plant becoming stalkless. Typically blooms lavender to purple to blue (rarely pink or white), August–November.
- Small white aster (S. parviceps). Scattered, mostly in the eastern half of the state. Upland prairies, upland forests, ledges and tops of bluffs; less commonly bottomland prairies, margins of ponds, and banks of streams; also pastures, old fields, and cemeteries. With its inrolled spinlike tips to its involucral bracts, it looks similar to white heath aster (S. pilosum) but is much less common and has smaller, fewer-flowered heads. Typically blooms white, August–November.
- Spreading aster (purple daisy) (S. patens). Scattered mostly south of the Missouri River. Glades, upland prairies, openings of forests; plus old fields, fencerows; mostly on acidic substrates. Typically blooms purple to bluish purple, August–October.
- White heath aster (S. pilosum). Common statewide, in a wide variety of upland and lowland habitats. Considered among the most widespread and “weediest” of our native asters, not common in high-quality native habitats, more common in overgrazed pastures, roadsides, and other disturbed places. Spindly-looking plant with many small needle-like leaves all along the flower stems. Flowerheads usually only about ½ inch wide. Typically blooms white (rarely pink), August–November.
- Willow-leaved aster (S. praealtum). Scattered nearly statewide. Bottomland prairies, moist depressions in upland prairies, banks of streams, rivers, and spring branches, fens, margins of ponds and lakes, bottomland forests and rich upland forests; plus ditches and other open, disturbed places. Often grows in dense colonies. With its attractively leafy branches and showy flowers, this is a good candidate for a wildflower garden, and it is often available at native wildflower nurseries. Reaches about 5 feet tall. Leaves rough, hairy, lance-shaped, to about 5 inches long, and about the same size all along the stem. Typically blooms purple or bluish purple, August–October.
- Glossy-leaved aster (S. puniceum). Scattered in the eastern half of the Ozark and Ozark Border divisions, with a disjunct population in Boone County. Fens, calcareous seepage areas along streams, and bottomland prairies. In our state, this species apparently represents relict populations from Pleistocene glacial times that survive and are confined to cool, moist microhabitats. Resembles New England aster, but lacks gland-tipped hairs on the flower stems, and hairs grow in lines along the stems. Typically blooms lavender to purple to bluish purple, August–October.
- Small white aster (frost flower) (S. racemosum). Scattered, mostly in the southern half of the state, most commonly in the Bootheel lowlands. Bottomland forests, swamps, moist depressions of upland prairies, banks of streams and rivers, margins of ponds, lakes, and sinkhole ponds, fens, and sloughs; also ditches, and other moist, open, disturbed areas. Typically blooms white (rarely pink), August–October.
- Silky aster (S. sericeum). Scattered in the Ozark, Ozark Border, and Unglaciated Plains natural divisions, north locally to Lincoln County and along the Missouri River to Atchison County. Glades, upland prairies, and loess hill prairies; dry, sandy places. This beautiful wildflower is available for sale at some wildflower nurseries and should be used more wildly in gardens. Named for the dense covering of silky hairs on the leaves, making them feel slick like silk. Typically blooms dark purple to nearly blue, August–October.
- Inland saltmarsh (freeway) aster (S. subulatum). Introduced. Scattered in the Bootheel lowlands, and apparently less common farther north and west. The native range of this species is in states to our south where it tolerates saline soils near brackish water habitats, but it has rather recently migrated northward in highly disturbed habitats, especially along roads that receive applications of salt during the winter. Where it is repeatedly mowed, this usually upright plant resprouts aggressively and forms a low, spreading, clump-forming plant. Distinctive for its hairless green to light bluish-green or sea green stems and leaves. This aster is a taprooted annual. Typically blooms white to pale bluish purple, September–January.
- Prairie aster (S. turbinellum). Scattered nearly statewide, but apparently absent from most of northwestern Missouri. Despite its common name, in our state this species is not usually found in prairies. In Missouri, it’s usually found in woodlands: openings in mesic to dry upland forests, glades, and ledges and tops of bluffs; often on acidic substrates. This showy species is a good choice for a wildflower garden. Typically blooms lavender to purple to bluish purple, August–November.
- White arrowleaf aster (S. urophyllum; formerly Aster sagittifolius). Scattered nearly statewide, but absent or uncommon in the far northwestern and southeastern corners of the state. Upland forests, margins of glades, ledges and tops of bluffs, banks of streams and rivers; also pastures, old fields, fencerows, and other disturbed places. Typically blooms white, August–November.
See “Status” below to learn why the genus Aster, which used to be so huge and contained many similar-looking plants, was divided into several smaller genera.
- The Tatarian aster (A. tataricus) is the only “true” aster (in genus Aster) found growing wild in Missouri. Native to east Asia, it’s planted as a garden ornamental. It can grow aggressively, forming dense colonies, and sometimes escapes from cultivation, especially in urban areas. It has distinctive, very robust basal leaves that are paddle-shaped, up to 2 feet long and 6 inches wide, and usually present at flowering time. The leaves become noticeably smaller higher on the plant.
Other native wildflowers called asters or false asters include:
- Members of genus Boltonia, especially B. asteroides, called false aster or false starwort, which is the most common of our 3 species of Boltonia in the state. It is used in native plant gardening.
- Flat-topped white aster (Doellingeria umbellata), formerly placed in genus Aster; it’s uncommon in Missouri, known only from fens in Lafayette County.
- Members of genus Eurybia (3 known from Missouri) used to be in genus Aster. Of these the most common, in northern Missouri, is single-stemmed bog aster (or southern prairie aster, E. hemispherica). In the Ozarks, forked aster (E. furcata) is scattered and uncommon. Large-leaved aster (E. macrophylla) has been recorded in four Ozark counties; because plants in Missouri populations of this species produce few flowering stems any given year, it is usually overlooked.
- Stiff aster (stiff-leaved aster; flax-leaved aster, Ionactis linariifolius) used to be in genus Aster. An attractive, clump-forming species, it grows scattered in the Ozarks, especially in acidic, rocky upland soils, and has gained popularity in native plant gardening.
- Upland white goldenrod (white upland aster; sneezewort aster, Solidago ptarmicoides), genetically, is clearly a goldenrod, but it looks a lot like an aster and was long considered one. It grows in Ozark open areas such as roadsides, glades, pastures, and prairies.
Height may vary from about 6 inches to nearly 6 feet, depending on species and growing conditions.
Statewide. Different species have different habitat requirements and regional distributions. Several species are grown as ornamentals. Some cultivars may have a variety of unusual characteristics.
Habitat and Conservation
Different species occur in different habitats, with some preferring moist, rich soils as in bottomlands and forests, and others preferring open, sunny, dry, or rocky locations. In addition to their own usual natural habitats, most species are also found along roadsides and railways.
Taxonomically, New World asters used to be placed in the formerly very large genus Aster, but recent research, using DNA sequencing, has convinced botanists that our New World asters belong in their own genera. The largest of these is genus Symphyotrichum. Counting all of North and South America, there are about 90 species in this genus.
There still are such things as “true” asters (in genus Aster), but those are all natives of Europe and Asia. Among the approximately 180 species remaining in genus Aster are several familiar garden flowers, many of which have been introduced throughout the world. Only one, however, has been found growing wild in Missouri: the Tatarian aster (A. tataricus), described above under “Similar Species.”
Native asters, along with goldenrods, mist flower, lobelias, and other showy late-season wildflowers, contribute to Missouri’s fall color in a big way. Scenic beauty contributes to tourism, and tourism contributes to our economy.
A number of New World asters are cultivated in gardens, and some of the species with larger heads and purple or pink rays are choice ornamentals for the garden. Be careful if you’re considering any of the species with smaller heads and white ray flowers, as most of them can spread aggressively by both seeds and by the rootstocks. If you’re looking for a native plant with large displays of white-rayed flowerheads, instead consider species of Boltonia (false aster), especially false starwort (B. asteroides), which would be easier to manage.
One of the hottest fields within the study of biology is called plant-insect interactions. It focuses on insects that eat, pollinate, live on, or otherwise interact with plants, and the specific plants they rely upon. In addition to providing information that helps agriculture, landscaping, forestry, and habitat management, this field of study also gives us solid information about the importance of all life-forms.
Humans are masters of language, and learning the word for a thing is equivalent to learning the thing itself. In botany, it helps to have strong language skills. First, you must learn the names for various plant parts and their descriptions. But then there’s the names of the plants themselves, where it helps to know some Latin. When this genus changed from Aster to Symphyotrichum, the endings of many of the species names changed, too, to match the gender of the new Latin name. For example, Aster cordifolius changed to Symphyotrichum cordifolium.
The enormous family that includes asters, daisies, sunflowers, dandelions, lettuces, and so on, is called the Asteraceae (aster-AY-cee-ee), named for the representative genus Aster. Before botanists standardized all plant-family names to be based on a representative genus name plus the ending "-aceae," this family was called the Compositae (com-POZ-uh-tee), a descriptive name based on the group's distinctive composite flowerheads.
The word aster means "star." It is used in the words astronomy (the study of stars) and astrology (the metaphysical study of how star positions, as seen from Earth, might affect people's lives). But here's a new one for you: asterology is the branch of botany dealing with asters!
Several aster species provide browse for deer, especially the basal rosettes of leaves during the winter months. Flowerheads and seedheads are eaten by turkeys and other wildlife.
Our native asters and other late-season wildflowers provide important nectar and pollen for insects, including many pollinators. At the end of the growing season, as many blossoms are winding down and turning into seeds and fruits, insects search energetically for the remaining blooms. Honeybees are stocking up for the winter. Migrating monarchs, sulphurs, painted ladies, and other butterflies busily visit asters. Meanwhile, mantises, assassin bugs, spiders, and other predators (which by late summer have grown to their maximum sizes) hang around these blossoms to hunt insects drawn to the last of the flowers.
In most New World asters, the center disc florets change color from yellow to reddish purple over time. This color change correlates with the aging of the flowerhead and a reduction of pollen available to insects, because the older flowerheads have already been visited plenty of times, and insects have already taken most of the pollen. Also, the quality of the viable pollen is diminished in these older flowerheads. The color change is a way for the plant to communicate to its pollinators.
Indeed: in a study of small white aster (S. racemosum), researchers demonstrated that the color change from yellow to red tells bees and other pollinators which flowerheads contain the most pollen, and which are least worth visiting. As a result, pollinators are more likely to visit the yellow florets, with the best pollen, which increases the plant’s chances of pollinating and producing seeds with another aster plant. Although the aster could simply close up its older flowerheads and get on with the task of making seeds, it benefits the plant more to keep the old blossoms open: the plant’s overall display of flowerhead clusters is bigger and showier for it, which serves to attract more insect pollinators from near and far.