Plants of the Eloise Butler Wildflower Garden

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 sharp 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 and turn reddish at maturity. 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 are small and light and require light and warm soil to break dormancy. Some require some cold stratification for germination. All should be surface sown.

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 and, while obscure, it was first applied by Christian Gottfried Daniel Nees von Esenbeck in the 1800s in describing the type aster for the genus. 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.