Stems: Calico Aster is a native perennial aster that grows on erect to ascending stems to 3 feet high with branching at the top of the stem. The lower stems have whitish hairs and are green initially but can turn reddish brown at flowering time.
Leaves are thin, lanceolate (broadest below the middle), alternate with lance-like tips, uppers and mid-stem leaves mostly stalkless, lower basal leaves with stalks, sometimes with a few sharp teeth from the middle to the tips of larger leaves. Lower leaves can be up to 5 inches long but usually drop off at flowering time. The upper surface is usually without hair but may have some roughness. The lower surface is much paler in color with hair on the mid-veins.
The floral array is a pyramidal form of an open panicle, formed by long-branched side stems that contain well spaced flowers on the upper sides of the branches, hence the alternate common name of "side-flowering."
The flowers have very small heads (about 1/3 inch wide) and have two types of florets: Around the outside are 8 to 15 ray florets with white to purple tinged rays, surrounding a central disc of 8-16 tubular disc florets that initially have cream to pale yellow colored corollas, but turn to darker reddish colors at maturity (which is typical of asters in this genus). The tip lobes of the disc floret corolla strongly reflex when the floret opens. The five stamens have reddish purple anthers and tightly surround the central style. These are exserted from the corolla when the floret opens. The outside of the flower head is wrapped with small oblong to linear phyllaries in 3 to 4+ series, unequal in size, with green diamond shape tips, appressed tight against the head, infrequently spreading. Sometimes these take a purplish tone.
Seeds are a dry narrowly conical 3 to 5 ribbed cypsela, 1.8 to 2.2 mm long, with a tuft of whitish hair for wind dispersion. These cypselae can be very light in weight, being about 250,000 per ounce. Seeds usually germinate in warm locations without need for cold stratification, but if stored, storage must be dry cold.
Habitat: Side-flowering Aster grows from branched caudices or small rhizomes forming clumps. It grows best in rich, wet-mesic to dry-mesic soils with partial sun. Full sun will usually stress the plant unless there is continuous moisture. It is often found at woodland edges and other partially shaded openings.
Names: The older scientific name for this aster is Aster lateriflorus. All the new world asters, formerly in the genus Aster, have 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. Both the older species name lateriflorus and the current lateriflorum refer to the lateral flowering branches. Classifying authorities often note a number of varieties of this species. There is no particular variety of this species recognized within Minnesota by either the DNR or the U of M Herbarium as native and authorities such as Flora of North America do not accept the varieties as they feel more research should be done.
The author names for the plant classification are: ‘A.Löve’ is for Áskell Löve (1916-1994) Icelandic botanist, co-founder of the Flora-Europaea project and professor at various universities in North America. ‘D.Löve’ is for Doris Löve (1918-2000), Swedish systematic botanist, active in the Arctic and collaborator with Áskell Löve on numerous publications. Together they amended the work of the first to classify the species - '(L.)' which refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: The flowers are similar to the White Heath Aster in size, but the leaves are much larger than those of the Heath Aster; contrary wise, the leaves are shorter and more oval than those of White Panicle Aster. These latter two asters have flowers in dense clusters, not like the side flowering branches of this aster. The Ontario Aster, S. ontarionis, is most similar but the underside of the leaves have hair, not just the mid-veins, the entire leaf is soft and flexible, the disc floret lobes spread, but not strongly reflex, and there are more ray and disc florets.
Above: The floral array with its lateral flowering branches. Drawing courtesy USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service.
Below: Flowers are only 1/3 inch wide, rays are usually white. The disc florets have pale yellow corollas with reflexing lobes. These disc corollas turn reddish at maturity.
Below: 1st photo - The floral array of the plant. 2nd photo - View of the phyllaries of the flower head. 3rd photo - Stems pick up a purplish tint with age and are hairy.
Below: The flowering side branches are ascending to spreading. Note the flowers are only on one side of the branch. 2nd photo - Small stalkless leaves appear within the flowering branches.
Below: 1st photo - a mid-stem leaf with the prominent central vein. 2nd photo - upper surfaces are medium green and a little rough to the touch. The pointed teeth are few and positioned from the mid-leaf to the tip. 3rd photo - The underside of the leaf is much paler color and the mid-vein has white hair.
Below: Seeds are narrowly conical, ribbed cypselae, with a whitish pappus for wind dispersion.
Notes: Eloise Butler first noted Calico Aster growing in the Garden on Sept. 12, 1909. In her day the accepted scientific name was Aster lateriflorus. On Oct. 8, 1914 she planted 51 plants from Washburn Ave in Minneapolis. She listed them as var. hirsuticaulis, but as explained above, this distinction is no longer held. In 1917 and '18 she added others from Mahtomedi MN.
Calico Aster was listed on Martha Crone's 1951 inventory of plants in the Garden at that time. It is is native to Minnesota in the northern 2/3rds of the state, excepting some of the western counties. In North America it is found in Canada from Manitoba eastward and in the U.S. from the central plains states east to the coast. Asters are difficult to study. There are twenty-four species just of Symphyotrichum listed by the DNR and the U of M Herbarium as being found in Minnesota, some with several subspecies. The variety that Eloise Butler specifies below is one of those not recognized by botanists today as a separately classified plant.
Eloise Butler wrote about in 1915 in Asters in the Wild Garden: "O, you cunning little thing!" we exclaim at the wee blossoms peeping out through the leaves densely clothing the diffusely branched stems of Aster lateriflorus - the so-called calico aster - the purple disks and pale rays forming a pattern on the background of the small green leaves. Aster lateriflorus var. hirsuticaulis has somewhat larger flowers with yellow disks and seems to form a connecting link with A. tradescanti, the Michaelmas daisy, [note: now known as the Ontario or Bottomland Aster] which is also sparsely found in the Garden. The variety has a stricter habit than the type."
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: 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.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"