Asters: The Flowers of Frost

Monarch Butterfly on New England Aster. Photo Courtesy of Greg Thompson, USFWS
There are dozens of blue or purple wildflowers to be found, but the blues and purples that most define autumn for me are those of the asters.
Photo Courtesy of Greg Thompson, USFWS

This is a beautiful time of year here. A walk through the Iroquois Refuge or a drive into the countryside in any direction provides enough beauty to lift one’s soul. So much in fact, that it is easy to miss some of our loveliest flowers, the late blooming blue and purple flowers of autumn.

There are dozens of these blue or purple wildflowers to be found amid the fallen leaves and the tan dying grasses. You can easily pick them out from the other late bloomers. Along roadsides: dayflowers, purple coneflowers and knapweed, a few lingering thistles, teasels, burdock and chicory. At pond edges: pickerelweed. In the woods: mistflower and water mint.

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But the blues and purples that most define autumn for me are those of the asters, the flowers of frost.

It is easy to identify an aster. It is simply an autumn daisy. The yellow “she loves me, she loves me not” rays of the midsummer daisies, sunflowers and black-eyed Susans are replaced by blue or purple; the brown “eye” by yellow. Well, not quite, because asters occasionally come in other colors too, including white and pink.

purple petal flower
It is not always simple, but it IS possible to differentiate the many local species of Aster.
Photo by Pixabay on

There are about 250 species of aster to be found in North America. A 2006 article by Ed Fuchs in the Niagara Frontier Botanical Society’s journal Clintonia lists 31 species to be found here in western New York. 

With a good wildflower book like Peterson and McKenny or Newcomb it is not always simple but still possible to differentiate the local species. They are, for example, much easier to identify than those of their fall neighbors, the goldenrods, with their many hybrids. The aster species names often help as well: heart-leaved, arrow-leaved, smooth, crooked-stemmed, purple-stemmed, azure, and bog.

Although its name doesn’t describe it, the easiest to identify and one of the commonest asters of this area is the New England aster. Its flower rays are a deeper and richer purple than any of the others. If you need confirmation, its three to six foot, straight, and hairy stems are crowded with narrow leaves.

Found along roadsides and across meadows, all of these asters are perennials, second-growth plants that have replaced less viable annuals but will, if the succession continues, give way in time to taller shrubs and trees.

Why do asters bloom late? Clearly there are advantages. Their hardy competitors, even goldenrods and ragweed, are dying back. This gives the asters access not only to the sunlight they need to drive photosynthesis, but also to insects, whose pollination assures the aster’s reproductive success.

Monarch Butterfly on New England Aster. Photo by Rick L. Hansen
Monarch Butterfly on New England Aster. Photo by Rick L. Hansen

I confirmed this insect attendance when I once paused to rest in a patch of crooked-stemmed asters, a pale violet variety. In the few moments I sat there, I watched honeybees, a bumblebee, a wasp, and two species of butterfly busily probing their blossoms for nectar.

These lovely flowers will stay around until the killing frosts and early snows of November. Then they will supply seeds for tree sparrows, goldfinches, wild turkeys and chipmunks.

As you take advantage of our breath-taking fall scenery, don’t miss this exceptional wildflower bonus: the asters.