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Giant Ironweed

Common Name: Giant Ironweed.

Scientific Name: Vernonia Gigantea.

What to look for?  Flat-topped clusters of lovely rose-purple, tubular flowers atop a tall plant. The Giant Ironweed is an upright perennial with a purplish green, stiff, central stem which branches at the top. The green leaves are oblong or elliptic in shape. The central stem terminates in a flat-headed panicle of flowerheads. The apex of each flowerhead consists of dozens of rose-purple disk florets which are shaped like flared tubes. Flowers give way to rusty seed clusters.

Where can they be found at Carillon Stonegate Pond? These Giant Ironweeds were seen in the restored prairie around APD HQ campus.

How big are they? Tall! Giant Ironweed grows from four (4) feet up to seven (7) or more feet tall. The large, but oblong leaves are approximately nine (9) inches long and two (2) inches across. Each panicle of flowerheads is approximately five (5) inches across.

Where do they grow and thrive? The Giant Ironweed is native to Illinois. And while it is more common in the southern part of the state, it is also found up north. Across the U.S., it is generally confined to the eastern half of the country. Primary habitats include prairies, other grasslands, old fields, roadsides, savannas, and woodland borders growing on dry to moist soils. It is especially common in overgrazed pastures.

When do they bloom? The blooming period of the Giant Ironweed occurs from late summer to early fall and lasts one month or so.

Do birds, insects or other wildlife associate with this plant? The nectar of the Giant Ironweed’s flowers attracts bee flies, butterflies, skippers, and primarily long-tongued bees. The caterpillars of various moths feed on this wildflower. Because of the bitter foliage, other animals shun this plant as a food source.

Interesting Facts About the Giant Ironweed:

  • The genus name 'Vernonia' was given in honor of William Vernon, an English botanist who worked in North America.

  • 'Ironweed' refers to the toughness of the stem and the fact that it is exceedingly difficult to dig up this species with a shovel.

  • In an average year, a single plant can produce as many as 19,000 seeds.

  • Giant Ironweed is also known as Tall Ironweed.

For more information on the Giant Ironweed and sources of information used in this blog (these are several of the sources that I am using to learn as I blog), please visit Illinois Wildflowers, Missouri Botanical Garden, The Ohio State University Weed Guide, and U.S. Forest Service Plant of the Week.

The Carillon at Stonegate community is very fortunate to have a variety of wetland, forest and prairie environments conducive to a variety of birds and other wildlife, insects and plants. Our community and the Kane County Forest Preserve do an exceptional job in maintaining this natural environment – both for the benefit of the birds and wildlife and for our residents to enjoy.


Take a hike and see what you can find – and identify!

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