Blue Wood or Heart-leaved Aster (Symphyotrichum cordifolium) began its seasonal bloom in late September, and amazingly, at the end of November it’s still possible to find some blossoms.

Like all Aster (Asteraceae) family members, each flower ‘head’ of Blue Wood Aster consists of many tiny flowers that bloom gradually over a period of several weeks, offering nectar and pollen to a variety of flower visitors.  Each Blue Wood Aster flower head has an outer ring of ice blue petal-like ray flowers designed to advertise this feast. Tiny tubular disk flowers form the center of the display; this is where Blue Wood Aster makes its bountiful food available in hope that while dining, visitors will pick up pollen and transfer it to another plant of the same species, enabling pollination to occur.

Blue Wood Aster’s disk flowers are pale yellow when they’re in bud and when they first open. They turn pink or magenta as they age, and when they have been successfully pollinated.  This color change is a signal to pollinators, directing them to the receptive yellow flowers which are not yet pollinated and that will reward them with nectar, and steering them away from blossoms that are already satisfactorily pollinated and will not produce a nectar reward.  This evolutionary adaptation makes the most efficient use of both the plant’s and the potential pollinator’s efforts.

To share in the bounty offered by Blue Wood Aster, I invite you to a virtual time-lapse visit to our garden in central New Jersey.  You can see the last Blue Wood Aster blossoms for this year, and a selection of the many of the visitors that this lovely plant hosted throughout the season. Notice that the potential pollinators are generally visiting the yellow disk flowers, those that are still open for business, not the pinkish flowers that have shut down their nectar production.

Bumble Bees are the most frequent visitors.

But many species of Sweat Bees (Halictid bees), and even Honey Bees dine on Blue Wood Aster nectar and pollen.

A Mason Wasp stopped by for nourishment.

Many fly species paused to drink, most disguised as bees or wasps in an attempt to appear threatening to potential predators.

Even late season butterflies and moths were able to refuel on Blue Wood Aster nectar.

Meanwhile, a Brown-hooded Owlet Moth caterpillar dined on the leaves and spent flowers of Blue Wood Aster.

Blue Wood Aster is native in much of the eastern half of the United States, and in British Columbia, Manitoba, Ontario, Quebec, Prince Edward Island and Nova Scotia in Canada. It can be found in a variety of habitats, including woodlands, meadows and roadsides.  There may still be some blooming near you!

 

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Resources

Eaton, Eric R.; Kauffman, Ken. Kaufman Field Guide to Insects of North America.  2007.

Eastman, John. The Book of Forest and Thicket.  1992.

Mader, Eric; Shepherd, Matthew; Vaughan, Mace; Black, Scott Hoffman; LeBuhn, Gretchen. Attracting Native Pollinators: Protecting North America’s Bees and Butterflies. 2011.

Rhoads, Ann Fowler; Block, Timothy A. The Plants of Pennsylvania.  2007

Wagner, David L.; Caterpillars of Eastern North America, 2005.

Wilson, Joseph S.; Carril, Olivia Messinger. The Bees in Your Backyard. 2016.

USDA NRCS Plant Database