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Plants of the Eloise Butler Wildflower Garden

The oldest public wildflower garden in the United States


Common Name
Ontario Aster (Bottomland Aster)


Scientific Name
Symphyotrichum ontarionis (Wiegand) G.L. Nesom


Plant Family
Aster (Asteraceae)

Garden Location


Prime Season
Late Summer to Autumn



Ontario Aster is a native erect perennial inhabitant of the Woodland Garden. Stems can be from 1 to 4 feet high, very hairy, particularly near the top and into the floral array, sometimes not hairy near the base.

Leaves are alternate, thin, lance shaped with the underside with dense short hair, longer hair on the midrib, the entire leaf very soft to the touch. Leaves are generally stalkless but larger basal leaves may have a short winged stalk. Leaves below the floral array also have a few coarse but shape pointed teeth and will have a pair of small wing-like growths at the stem. More basal leaves are usually dropped by flowering time.

The floral array is a loose open panicle of spreading to ascending branches with the flowers occurring in small clusters.

Flowers: The small flowers are 1/3 to 1/2 inch wide and composed of two floret types. The outer ray florets have from 15 to 26 white rays. These are pistillate and fertile. They surround 12 to 25 disc florets. The disc florets are tubular with a 5-lobed yellow corolla (sometimes cream color), the tips of the lobes, which are rather long, are pointed and flare outward, similar to many other aster disc florets. Toward flower maturity these turn reddish-purplish in color. Disc florets have 5 stamens that tightly surround the single style which has appendages at its tip. The style is exserted from the corolla throat when the floret opens. Anthers are a darker shade of yellow. The flower stalk has some small leaf-like bracts, hairy, which grade into 4 to 6 series of phyllaries around the flowerhead. The phyllaries are unequal in size, narrow and linear in an overlapping series with the outer ones the shortest. Each has a green mid-rib terminating in a pointed diamond shape tip. Tips are usually appressed, but sometimes spreading.

Seed: Fertile flowers produce a dry 3 to 5 nerved gray to tan cypsela, 1.3 to 1.8 mm long, with a white pappus for wind distribution. Seeds of most asters require some cold stratification for germination.

Varieties: The two accepted varieties of S. ontarionis are var. ontarionis where the underside of the leaf is moderately to densely hairy, and var. glabratum where the underside leaf surface is smooth or almost smooth. The former is the only one native to Minnesota.


Habitat: The plant grows from a creeping rhizome in moist meadows and woodlands and thus produces colonies of plants. Partial sun is acceptable.

Names: All the new world asters, formerly in the genus Aster, have now been reclassified, most into the genus Symphyotrichum. The genus name is from the Greek symphysis, for 'junction', and 'trichos', for hair, all of which relates to a fine division by botanists of certain plant characteristics. The species name, ontarionis, refers to "of Ontario" although this aster is now considered less common there. The former botanical name was Aster ontarionis. A much older botanical name for this aster is Aster tradescanti and Aster missouriensis. More notes about that at the bottom of the page. The author names for the plant classification are: ‘Wiegand’ is for Karl McKay Wiegand (1873-1942) American botanist, head of the botany dept. at Cornell University and authority on taxonomy and author of over 100 papers. His work on this species has been revised by ‘G. L. Nesom’ who is Guy L. Nesom (b. 1945) American botanist who has published papers on the nomenclature of asters.

Comparisons: A confusing relative is the Calico or Side-flowering Aster, S. lateriflorum but there the flowers appear more strongly on one side of side-branching stems and the disc florets have shorter corolla lobes. There are also fewer ray and disc florets; the disc floret lobes strongly reflex not just spread; the underside of the leaf has hair only on the mid-vein and the plant produces clumps but does not normally spread creating colonies of plants.

See bottom of page for notes on the Garden's planting history, distribution in Minnesota and North America, lore and other references.

Ontario Aster plant drawing

Above: The floral array is an open panicle, with flowers on ascending branches. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.

Below: 1st photo - The disc florets have a yellow corolla tube with out-flaring tips. 2nd photo - The phyllaries of the flower head are in several series, longest inner, with dark green tips.

Ontario Aster Flower Ontario Aster bracts

Below: 1st photo - A branch of the flowering panicle. Note the short hair on all parts and the leafy bracts. 2nd photo - Stem leaves have a few coarse but sharp teeth and little winged growths at the base. 3rd photo - The underside of the leaf is densely hairy, as are the edges of the small leaves and the stem.

Ontario Aster flower branch Ontario Aster lower leaf Ontario Aster stem

Below: The larger lower leaves (bottom) may taper to a short winged stalk while the very upper stem leaves (top) are stalkless, otherwise they are similar in shape.

full plant
full plant


Notes: Ontario Aster is indigenous to the Garden. When Eloise Butler composed her 1915 list of asters in the Garden, both native and introduced, this one was listed as indigenous (using the older name A. tradescanti) with the note that it was the Michaelmas daisy and sparsely found in the garden. In referring to this aster as the Michaelmas daisy she may have been referring to a convention of her time. All asters at one time were considered as "Michaelmas daisies" due to their bloom dates at the change of the season, particularly those species that could still be blooming at Michaelmas on Sept. 29th. This species is one of them. Today the name is more generally applied, except for certain asters that the nursery trade has given the Michaelmas Daisy name to, such as the New England Aster. The old botanical name for this aster, A. tradescanti, refers to the 17th century plant collector, John Tradescant Jr., who brought a number of the new world asters back to Europe, where the Michaelmas name originally got attached.

Eloise planted more of them in Sept. 1918 - plants from Washburn Park; and in 1919 from Minnehaha Park. Additional plantings occurred in 1922, '23, '27, '28. and '31. Curator Martha Crone planted Ontario Aster in 1936, '37, and 45 in 1943. Today it is more numerous. In Minnesota Ontario Aster is found in 1/4 of the counties, most concentrated in the SE quadrant of the state, including those of the north metro area. In the U.S. it is found from the central plains eastward except for the coastal states and rare in New England. In Canada it is known in Ontario and Quebec. There are twenty-four species just of Symphyotrichum listed by the DNR and the U of M as being found in Minnesota, some with several subspecies.

In 1915 Eloise wrote an essay about her asters that was sent to The Gray Memorial Botanical Chapter, (Division D) of the Agassiz Association for publication in the Asa Gray Bulletin. Text here.

References and site links

References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.

graphicIdentification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.