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In the Highways, In the Hedges: The Aster Family - Thistles and Their Cousins

The hottest thistle in town! Just ask these Black Swallowtails.

As a kid, one of my Dad's farm chores was removing thistles with a large sickle. He stood far back as he did so. You know why he did if you've ever accidentally gotten up-close and personal with one of these prickly plants. They can cause some serious scratches, sometimes accompanied by an impressive rash. And prolific? They practically invented the concept. Thistles come to STAY. They multiply like crazy, and they take over. Nobody loves thistles. Not gardeners, not farmers, not native plant enthusiasts. Nobody. Unless you love butterflies and things that are purple, and then you secretly love thistles because you know what a nuisance they are.

Musk Thistle at Cave Springs Natural Area

Here in Arkansas, we have a few different kinds of thistle: Musk (Carduus nutans), Bull (Cirsium vulgare), Yellow (Centaurea solstitialis) and Field (Cirsium discolor) are our most common types, with the entire genus of Cirsium being listed as noxious weeds. But it's not all bad news! We do have some natives, such as the Tall Thistle (Cirsium altissimum), which bloom late and set seed just as the Goldfinches are beginning to nest.

The Goldfinches put the finishing touch on their nests by lining the inside with soft thistle down plucked from thistle plants. The thistle seeds ripen just as the baby Goldfinches hatch, their first meals will be regurgitated thistle seed feed by both parents.

Arkansas Master Naturalists

Plus they're gorgeous, and purple, and butterflies love them utterly. Confidential to everyone: I am now accepting applications for the Secret Thistle Fan Club. Details pending.

Thistle Fan Club, founding members. Left to right: Fiery Skipper, Bumblebee, Eastern Swallowtail, Great Spangled Frittilary. All pictures from Lake Fayetteville.

Also delightfully purple, and actually welcome in our forests and gardens are the Ironweeds. Named for the toughness of their stems, Ironweeds are another favorite among pollinators, acting as food source and host for many butterflies and skippers.

Altalopedes camestris: Sachem, a small skipper butterfly, enjoying some ironweed near my house.

We've got seven Ironweeds that are common here, with some notable natives like Baldwin's Ironweed (Vernonia baldwinii), and Great Ironweed (Vernonia arkansana). It's not difficult to tell Ironweeds apart, but it's fiddly and technical, requiring a good look at different parts of the plant. Ironweeds will also hybridize where ranges overlap, which complicates identification.

Vernonia Arkansas: Great Ironweed at Lake Leatherwood

A hybrid of Vernonia Arkansana near Blossom Creek in Rogers, AR

While you probably won't feel a need to definitively identify an Ironweed (I rarely do), you might want to know if what you're admiring is a Thistle or an Ironweed. While this is not true in all parts of the country because of different plant varieties, I find that it's pretty easy to distinguish them here. The flowers on Ironweeds are smaller than thistles, and there are usually many more flowers. A closer look at the Ironweed flowers will also reveal little curlicues, like those seen above.

The Asteraceae family reunion wouldn't be complete without mentioning knapweeds, blazing stars, and gayfeathers. Sunflowers are also members of the family Aster, but I feel like they deserve their own post, so we're just concentrating on Team Purple for now. I don't see as many bees and butterflies on these thistle cousins, but I always notice their vibrant color and fireworks-like flowers.

Liatris hirsuta: Hairy Gayfeather at Lake Wilson; Centaurea maculosa: Spotted Knapweed at Lake Wilson; Liatris aspera: Rough Blazing Star at Roaring River