Edible wild plants: A guided tour at Theresa Marsh

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Theresa Marsh State Wildlife Area is not small. From County Highway 28, which cuts across the northern end of it, a vast sea of cattails stretches nearly to the horizon. I’d never heard of it, however, until I went there recently for a hike led by Dianne Robinson, a naturalist with the Wisconsin DNR.

Sandhill cranes

I’ve seen the Wildlife Area before—many times in fact. It is adjacent to Interstate 41, which I’ve driven often on my way to points north. But the small wooden sign identifying the marsh has escaped my notice and the wetland is out of sight from the freeway, beyond a tree line.

Hunters know the area though. That was easy to tell and not only from the numerous signs indicating where they could and couldn’t hunt. I wasn’t there long before a group of hunters came out of the marsh with two canoes and two brace of enormous-looking goose carcasses.

But I wasn’t there to hunt. I joined about a dozen other folks who came to learn about edible wild plants. The “hike” turned out to be a short stroll along the dirt road leading to a gravel parking area next to the marsh. The edible plants we found there were mostly very common ones like dandelions, yarrow, chicory and even cattails. Believe it or not, cattails produce more edible starch per acre than any other green plant! Whoa. Who knew? (Well, the U. S. Army did. There was a plan to use the plant for the war effort during World War II, according to a website called “Eat the Weeds.”)

As you might expect, the edible parts of many wild plants don’t often look like recognizable foods, except for berries and salad-like leafy greens. The most obviously food-like plant we found was wild grape. Although smaller than commercially grown blueberries, let alone grapes, they hang in clusters just as you can imagine.

Clusters of wild grape on the vine

The other thing about edible plants is they tend not to be photogenic, especially when the edible parts are underground as with wild parsnip. We learned that if we were to dig up the root it would look very much like the ones in the grocery store. However, although it has an edible root, wild parsnip is better left untouched. If broken open it oozes a chemical that can cause severe, painful burns when exposed to the sun. The resulting blisters can leave long-lasting scars.

I did manage to get some photographs of a few of the plants, edible or not, as well as of the surrounding landscape. Robinson, our guide, said that her primary purpose in offering the hike was not so much to educate people about the plants as to acquaint us with the marsh. I am following that lead. She told us that, unlike most parks and except for sections designated as refuges, you are free to wander around off trail in wildlife areas such as this one. (I would be cautious about that during hunting season, though! Wear bright colors.)

Robinson with milkweed, the fresh shoots of which are edible. The sap of the plant, however, is toxic. “I would never eat any plant in the wild unless I knew it was safe.” Robinson repeated this advice like a mantra every now and then during the hike. Milkweed, of course, is a well-known food source for monarch butterflies if not humans.

 

The berries of the hawthorn are edible, if you can safely pick them from among the seriously threatening thorns! And then, after you have braved your way through the thorns to grab a handful of ripe berries you must remember to spit out the seeds. They contain cyanide. Yes. Deadly. (See Robinson’s advice, above.)

The Rock River spills out of Theresa Marsh at the point where we were hiking along the road. Across the wetland surrounding the river we could make out the rooftops of Theresa Station.

The tiny unincorporated hamlet consists of a dozen or so buildings along a dead-end road leading to, yes, a railroad. I assume it once had a station.

Smartweed, which grows in and near the wetter places, blooms from June through September. Not edible but pretty, said Robinson. Eat the Weeds claims it is in fact edible, but so strong and spicy as to not being worth the effort—like eating “a piece of burning paper.”

Robinson holds up a wild cucumber. The name might easily fool you into thinking it is edible. The spiky “cucumber” is a seedpod and is as inedible as it appears! 

Considering our topic, I should note that foraging for certain types of edibles, such as berries, nuts, and mushrooms, is legal on state lands like this. You are not allowed to harvest other parts of plants, including seeds and roots. The official guide is on the DNR website.

On my way back to Milwaukee after the tour ended I found another lovely view of the marsh beneath a sky dotted with Georgia O’Keeffe clouds. Widely dispersed clumps of brown-eyed Susans and goldenrod appeared almost to mirror the stippled sky. If you want to go there, Theresa Marsh State Wildlife Area is just off Interstate 41 between Highway D and Highway 28 and only a few miles east of its more famous neighbor, Horicon Marsh.