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Swamp Thistle

Common Name: Swamp Thistle.

Scientific Name: Cirsium Muticum.

What to look for?  Lovely pink spike-like flowers (Note that I avoided using “Thistle” and “lovely” in the same sentence!). The Swamp Thistle has a hollow six foot stem. The leaves are medium to dark green, deeply cut and pointy – but not sharp.  Each stem terminates in an oblong, light green bud or flowerhead with hints of pink. It has a cob-webby appearance with fine white hairs. At the flattened top of the flowerhead during bloom, there is a dense cluster of numerous disk florets; there are no ray florets or petals. The corollas of the disk florets are narrowly cylindrical. These corollas vary in color from pink to pinkish purple.

Where can they be found at Carillon Stonegate Pond? From mid-summer and through September, you can find the Swamp Thistle in bloom scattered around the shoreline and banks of Carillon Stonegate Ponds.

How big are they? Swamp Thistle can grow to as much as six feet tall. The leaves are up to eight inches long and up to three inches across. Each flowerhead is about one and one-half inch long.

Where do they grow and thrive? The Swamp Thistle is native to the continental U.S. and is common across northern Illinois. Habitats include wet, sandy prairies, sandy swamps, marshes, fens, swales between sand dunes near Lake Michigan, and pastures.

When do they bloom? The blooming period of the Swamp Thistle occurs through summer from late June to September.

Do birds, insects or other wildlife associate with this plant? The flowerheads of Swamp Thistle attract many insects, including bumblebees, honeybees and other longer-tongued bees, Hummingbird Clearwing Moth as well as butterflies. Some small songbirds eat the seeds of thistles, especially the American Goldfinch, which also uses the hair tufts of thistle seeds in the construction of its nests. The Ruby-Throated Hummingbird occasionally visits the flowerheads of thistles for their nectar.

Interesting Facts About the Swamp Thistle:

  • The seeds of the Swamp Thistle are long, oblongoid, and dark brown to black with bands of yellow at their upper ends, distributed by the wind and enjoyed by the American Goldfinch.

  • Most people do not grow thistles as ornamentals around their yards and gardens, but the flower is attractive and is welcoming to bees and butterflies.

  • Thistles are unloved; as the late U.S. Poet Laureate Maxine Kumin stated in one of her poems: “Sheep will not eat it / nor horses nor cattle / unless they are starving” and it is “choking the sweet grass / defeating the clover”.

For more information on the Swamp Thistle 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, University of Texas Wildflower Center, Friends of the Wildflower Garden, Minnesota Wildflowers and an article, The Good Thistle.

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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