Butterweed, Butterwhat?

A green wood by a river

A surprising flower in Thatcher Woods

At this time of year, the woodland savannah is green, green, green. The spring ephemerals have quit blooming and the summer players—woodland sunflower, Joe pie weed, the grasses and goldenrods—are still mustering their strength. So as you walk through the green shade, there’s not much color—oh, some delicate white sweet Cicely, perhaps, but little more than that. It’s enough to make one wonder how the butterflies and bees are getting their nectar and pollen. You get your "plant eyes" on, in the sense that you are identifying by leaf shape, habit of growth and shade of green: you focus on fundamentals, on what really characterizes each plant, rather than the gaudy flower.

So there a fellow forest preserve volunteer and I were last week, walking through the bottomland along the Des Plaines River, comparing specimens of Asian and native honeysuckle, avoiding poison ivy, noticing the raspberries coming along, listening to the bull frogs croaking and the woodpeckers and robins commenting on perceived conditions, and generally enjoying the green gloom, when a vast flare of sunlit yellow caught our eyes. Across a flooded river inlet was at least an acre of three-foot tall plants topped by bright yellow flowers where such things shouldn’t be, as if a crew of flashy strangers had crashed a Quaker meeting. We were compelled to investigate, which involved some navigation around the water and dealing with a muddy sloping bank.

What we found was a plant neither of us recognized. Now, without boasting I can say I am familiar with most of the plants in Thatcher Woods: even if I don’t yet know their names, I recognize them, like neighbors from the next block over. And my friend is pretty good, too. There are also various plants I’ve read about and then recognize when I encounter them, as when I first saw hoary puccoon in a dry prairie I was visiting. But this? Deeply lobed leaves, a daisy-like composite flower, seed puffs like a dandelion, and a ridged hollow stem—nope, never saw it before. Never expected to see it or knew to look for it. Could it be a Senecio, a ragwort, of some kind? Well, it didn’t match anything in the Peterson’s Field Guide to Wildflowers I had with me. Those leaves. That somewhat brittle, easily snapped, hollow stem. We figured it might be a non-native invasive, introduced since the book was published.

Later I described the plant to my colleague, an environmental biology instructor, also a plant geek and a superior sleuth. The next day a name, Senecio glabellus—alternatively Packera glabella, common name butterweed—and links to Missouri and Ohio websites showed up in my in-box. The plant is also called cressleaf groundsel (“groundsel” is from an old Anglo-Saxon word “groundeswelge” meaning ground swallower) and it is toxic to grazing animals—though deer have enough sense to avoid it. Now that I had the name, I could easily check Swink and Wilhelm’s Plants of the Chicago Region: they say the plant is native to southern Illinois, but has been introduced in Du Page County. Illinois Wildflowers says the same and gives it the epithet “weedy,” adding that its native range has expanded north from southern to central Illinois. Yet here it is, ensconced and happy in Cook County.

A couple of days later I went back to take pictures. There had been rain, and the whole area was flooded. A doe and two fawns appeared nearby, sensed me upwind and moved off, not too fast. A bullfrog croaked. A great blue heron grunted in a slightly higher key. The butterweeds stood blooming bravely, up to their waists in water.

Related Posts:
A Date with Some Turtles
Gardening in Thatcher Woods, with Help
Behold the Inglorious Garlic Mustard