Thursday, June 23, 2022

Mysteries in the Fen: Bladderwort Turions

The warmth of the water was comforting, and I reveled in the textures on my soles. One step sunk into fuzzy sphagnum moss and the next oozed silky muck up between my toes. It’s hard to believe this all was frozen solid just a few months ago. I moved cautiously, placing each foot deliberately and testing the substrate before shifting my weight and committing to the step.

Caution was warranted not only because I was barefoot and wary of impaling myself on a hidden stick, but also because I was nearing the edge of one of several pools of open water that dot the bog mat. I’ve tried to measure the depth of these pools—but ran out of gear at 95 feet. The bog mat that supported us above those fathoms was simply a woven mass of poorly decomposed vegetation called peat.

Cade and Olivia, the Museum’s two new Summer Naturalist Interns, were exploring the fen (like a bog but with groundwater flow) with me. A dark mass of adorable, wiggling, toad tadpoles pulled us toward the edge of the open water first. Then Cade spooked a young garter snake out of a clump of leatherleaf and it swam to safety on a little island of peat. Dragonflies and damselflies darted around the stems of bog rosemary, sedges, and other wetland plants at the water’s edge. Their shimmering wings added an aura of magic.

“Oh!” I exclaimed happily, as a submerged plant caught my eye. Its thin, branching, bottle-brush leaves looked somewhat similar to coontail or even watermilfoil, but I knew better. “Bladderwort!” I exclaimed. I’ve written about this carnivorous plant with yellow snapdragon-like flowers before.

While individual bladderwort leaves are pretty insubstantial, they can grow in thick masses in wet ditches and shallow ponds. Photo by Emily Stone.

Pulling up the whole plant—this species grows as a free-floating leafy stem less than a foot long—I found the namesake bladders. Smaller than an apple seed and of a similar shape, the translucent capsules sparkled in the sun. That beauty is deadly.

Flat-leaved bladderwort, Utricularia intermedia 

Each bladder, nestled among the thread-like leaves, is a trap with a door that opens inward. The plant can pump water out of the bladder, flattening it and creating a vacuum inside. Bristles near the trapdoor look like a good feeding habitat and act to funnel tiny prey toward their demise. When a minuscule invertebrate nudges trigger hairs near the door, the flap swings inward and sucks in both water and lunch. The door snaps shut as the bladder fills.

This translucent bladderwort trap is also a stomach. Tiny aquatic creatures trip trigger hairs, get sucked in, and then digested. Photo by Emily Stone.

Digestive enzymes and resident bacteria digest the prey, which takes anywhere from fifteen minutes to two hours, depending on their size. To reset the trap, the plant uses special cells to pull nutrient-laden water into the stem. Not only does this feed the plant, it restores the vacuum that is essential for the capture of future prey.

There are over 200 species of these hungry little plants worldwide, and although they live everywhere except Antarctica, their centers of diversity are in South America and Australia. Across all of their range, they live in moist soils or open water that is nutrient-poor. Their carnivory compensates for that deficiency.

It’s kind of neat that we in the Northwoods have something in common with the tropics…but there’s one BIG difference, right? Winter.

The stem of bladderwort I picked up had more than one type of bulbous appendage. In addition to the pale bladders, at one end was a green mass the size of a pencil eraser. This is the key to their winter survival. The shortening days of late summer induce the formation of this turion—a dormant bud that is capable of growing into a complete plant. It is essentially a shoot that waits to elongate. All the leaves and stems are there—just crowded together. Many aquatic plants overwinter as turions.

The overwintering turion of a bladderwort is made of tiny leaves all scrunched together. Photo by Emily Stone.

Curiously, the same plant hormone (abscisic acid) that triggers trees to lose their leaves in the fall also instigates bladderwort’s turion formation and keeps them dormant even through balmy fall weather. As winter approaches, the dying stem drags its attached turion to the bottom of the pond, out of reach of killing ice.

In the spring, warming water triggers changes that increase gas content. Supposedly, the turion then detaches from its mother plant and rises to the surface, breaking dormancy after just two warm days.

But along the edge of this pool in the fen, I found several turions that had not started expanding and were still attached to their stems. What happened? Did they sink down 95 feet and then rise back up? Did they nestle into a corner of the bog mat and use sphagnum as a cozy blanket? When will they begin to grow?

And what new mystery will I discover the next time I go squishing around this magical place with muck between my toes?

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and to see what we are up to.

Thursday, June 16, 2022

Cotton, Not Cottonwood

Just back from a hike and eager to see what my camera recorded, I plugged my memory card into the computer. I thought I’d captured nodding trillium in just the right light, and I knew my photos of columbine were well-framed between two trees. I’d done my best to focus on a tiny spider hiding among the bright, pollen-filled anthers of a white trillium.

But zooming in on these photos, I noticed something wrong: each of these flowers was fuzzy. No, it wasn’t a faulty autofocus, the images were pretty sharp. It’s just that the flowers were truly covered in fuzz.

The columbine flowers—with their five red nectar spurs pointing skyward on delicately arching stems—were the worst. Was that dryer lint in the woods? And then I remembered: the small rock outcrop where they grew was surrounded by aspen trees. The path had been littered with aspen catkins erupting in white fuzz. My fingertips had a memory, too, of the sticky feeling of columbine stems—the perfect tackiness for capturing fuzz.

Off the cuff, many folks would tell you that the white fluff flying on the breeze this time of year is from cottonwood. The thing is, Eastern cottonwood—Populus deltoides—is pretty rare in the northern third of Wisconsin. But, as it turns out, the white fuzz is a family trait, and local relatives abound.

Cottonwoods are in the willow family, along with aspens and poplars. And, as is typical in plant families, their flowers are all very similar. Although tiny and lacking pretty petals, the flowers cluster together on long, drooping catkins that emerge before the trees’ leaves. With a lovely yellow-green hue, they provide us with some of the first colors of spring.

The flowers’ early emergence is necessary, because they are pollinated by the wind. Spring breezes filter through bare twigs to pick up pollen from catkins on a male tree and deposit it on the catkins of a female tree. Yes, individual trees are one sex or the other, a trait that botanists call dioecious, which means “two houses.”

Catkins of male flowers simply drop to the ground once they’ve sent their pollen on its way. After they are pollinated, the female flowers develop into small, green fruits that are all lined up on the catkin like a braid of chili peppers.

The green fruits on this aspen catkin have split open to release their tiny seeds—each surrounded by a tuft of fluff that will carry it away on the breeze. Photo by Emily Stone.

Once the seeds are ripe, the capsules split open and curl back adorably—like elf shoes. Out pour tiny seeds, each surrounded by a halo of cottony fuzz. While many allergy sufferers grumble during this phase, the fluff is not the cause of allergies—the pollen that fertilized those seeds was the problem.

Between their small size and mini-parachutes, aspen seeds drift easily on the wind. Their window for world travel is brief, though, since the seeds only remain viable for a short time. Some seeds, like oaks and cherries, fortify themselves for a long wait, banking on patience to help them win the reproduction game. Willow family seeds play a different game—investing a minimum of energy but producing gobs of seeds. Most seeds succumb to desiccation, or fail to land on suitable soil for germination.

If all of the seeds seem to land on your lawn, creating an annoying carpet of natural lint, there’s a fun way to get rid of them. I recently saw a video of a park in Spain (Populus trees grow worldwide!) where someone had set fire to the cotton! Like a mini version of a prescribed prairie fire, the dry cotton burned quickly and left the lush green grass untouched.

Seeds that do win the jackpot of soil moisture, temperature, and sunlight germinate rapidly and begin the race to grow. This is one reason aspens are pioneer species. When a site has been disturbed by a forest fire, flood, or landslide, seeds can float in and grow quickly in the abundant sunshine. Once established, aspens spread by sending new clones up from their roots.

Since many groves are made up of clones of the same individual, a large area may be entirely male or entirely female. Male trees don’t make seeds, and therefore don’t make cotton, either. The forest around my fuzzy columbine flower was female.

If you find yourself irritated by all the cotton drifting around, take a moment to appreciate that across the Northern Hemisphere, dozens of species of cottonwoods, aspens, and poplars are sending their tiny seeds out onto the breeze. And everywhere they land, people just like you are grumbling about the mess.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and to see what we are up to.

Thursday, June 9, 2022

Nature’s Drumbeat

By Guest Writer Anne Torrey

Columnist’s Note: Anne Torrey, of Gordon, WI, participated in a Natural Connections Writing Workshop I led last fall, and is continuing to hone her craft. I hope you enjoy her unique account of witnessing a common event—the drumming of the ruffed grouse. While the first drumming reached our ears months ago, the subtle beats still echo through the woods as males assert their territories and make sure they’ve attended to all of the ladies.

–Emily Stone, Naturalist/Education Director at the Cable Natural History Museum.

We were glad to be hiking in the forested hills despite the miserable weather. The air was fresh with the loamy scent of decaying leaves, and the wonders of early spring filled our senses. Tiny green buds pushed their way upward and out, while the chirping birds joyfully gathered more materials with which to fortify their nests. The creek was rushing with water from the recently melted ice, overflow soaking beyond the marshy edges. Woodpeckers were noisily tapping away, searching for lunch.

Anne and her dog Tug love to explore the spring wood. Photo by Eli Torrey.

About five miles in, we came to a large stand of mature aspens. Stopping for a moment, I was startled to hear what sounded like a helicopter, rapidly gaining speed. Suddenly it stopped. Huh? Wait, there it was again, only this time it sounded more like an old boat motor starting up, quickly gaining RPMs. Put…put...put…put..put..put.putputput. Then it stopped.

Confused, I looked at my husband who smiled and gestured toward Tug, whose tail was sticking straight out, ears perked, and staring into the woods. He lifted a paw. He was pointing! Eli and Tug had heard this before and knew exactly what was happening. We were being treated to a performance of spring drumming of the male ruffed grouse. A grouse makes this motor-like sound by standing on a drumming log about a foot from the ground. He stretches himself tall, and begins beating his wings against the air, ever more quickly, creating a vacuum, much like lightning creates thunder. Only instead of a loud BOOM! we get the pulsing thumpthumpthumpthump of a vintage two-cylinder tractor.

“Tuggy SIT!” Eli said quietly. “Good boy!” As we searched the woods for the source of the drumming, we noticed movement straight out to the left of our position. Grouse are difficult to spot due to their brown speckled feathering. Unlike many species, the male ruffed grouse cannot use showy good looks to attract a mate; instead he relies upon this fantastic musical show. As we watched and listened to his amazing display, we kept our eyes peeled for any interested females.

Typically, a male (sometimes called a Thunder Chicken) keeps his six-to-ten acres to himself and stays put for life. One or two females may also live in his territory, but they do not constitute a partnership. Once mated, he returns to his bachelor pad and the female moves as far as a half-mile away. She makes her nest in the leaves at the base of a tree stump or clump of brush.

Over a two-week period, the single mom will lay a clutch of 8-14 buff-colored eggs. She waits to begin incubating until she has laid the last egg, so that all of them will hatch at about the same time, in less than a month. Once the thumb-sized chicks have dried off, they are ready to leave the nest and begin foraging for protein sources like insects and tiny animals. As they grow, they will gradually switch to a diet of primarily fruit and green plant materials.

The little ones begin to fly short distances at about five days old, resembling tiny, feathered bumble bees. Due to multiple factors, only about 45% make it to fall. As adults, their numbers are further diminished by hunters, predators, and their own clumsiness! Grouse fly in startled spurts when disturbed, and occasionally meet their demise by crashing into trees—or your car—in a moment of panic.

The aspen grove is the favored home of the ruffed grouse, as it has an abundance of winter buds and then fresh leaves. Later this spring, we will return to this spot and perhaps Tug will point out some flying “bumble grouse” chicks so we can observe the next phase in the life cycle of the ruffed grouse.

This grouse found some unusual objects on a potential drumming log in the middle of a Boundary Waters campsite. Photo by Emily Stone.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and to see what we are up to.

Thursday, June 2, 2022

The Sunny Chemistry of Marsh Marigolds

Cold mist pelted my face as I biked along the narrow shoulder of the county highway. Earlier in the morning I had been overly optimistic about the forecast and the weather radar, with the end result of me bike commuting in the rain. The chill seeped inward, and my thoughts followed, so that soon I was grumbling wordlessly in my head about the soggy, gray weather.

One look upward was all it took to brighten my mood—something golden was shining through the misty swamp. No, not the sun—it was a huge patch of marsh marigolds! With large, vivid green leaves, and yellow, cup-shaped flowers, these members of the buttercup family provide lovely patches of color even in soggy wetlands. Their scientific name, Caltha palustris, means “goblet of the marsh” Suddenly, riding my bike in rain became a lot more pleasant.

While the showy flowers may beckon you to take some home, all buttercups can cause irritation and blistering of the skin if handled. Swallowing any part of the plant can cause intense burning of the mouth and digestive tract, followed by nausea and convulsions. All mammals, not just humans, seem to be affected. Luckily, a bitter taste warns of the inedibility of this common plant, and lethal poisonings are rare.

The culprit for these nasty reactions is a chemical called ranunculin, named for the Ranunculaceae family in which is it found. Ranunculin is both an “antifeedant” (a chemical agent that causes a pest to stop eating), and an insecticide. In one study, worker ants who encountered ranunculin showed a 19% increase in their mortality rate, and the authors suggested further research into the chemical for commercial pest control.

So how does a plant even begin to make a toxin like this? I’m not a chemist, but from piecing together information in a Wikipedia and Google Scholar treasure hunt, this is my explanation: The marsh marigold manufactures glucose, a type of sugar, during photosynthesis. Then, another small organic molecule is bound to the glucose, creating the glycoside called ranunculin.

Many plants store chemicals in the form of inactive glycosides like this. Glycosides are activated when enzymes break off the sugar molecule, making the other chemical available for use. In the case of ranunculin, it breaks down into protoanemonin, which is the glycoside chemical that causes the skin and bowel irritation associated with marsh marigold.

Plant glycosides are often used as medications, and marsh marigold has a long list of traditional medicinal uses. Do you need to remove a wart? Cure a cold? Ease the symptoms of anemia, convulsions, or coughing? Marsh marigold has been used to treat all of those, although there is little modern medical evidence to support its use.

With further exposure to air and water, the skin irritant protoanemonin is changed to the more benign chemical anemonin, which German scientists have found to have antispasmodic and analgesic properties. It, and not protoanemonin, may be responsible for the medicinal properties of marsh marigold. Or maybe they work together. Both medicine and nature are complicated.

This beautiful spring flower is also listed as an edible, with many cautions. Leaves and tightly closed buds must be boiled in a few changes of water, and while the leaves can then be eaten like spinach, the buds still need to be pickled for a month to be safe. All of these techniques probably help to change the toxic protoanemonin into the less hazardous anemonin. Still, I don’t think I’d mess with it.

It’s hard to imagine all of what goes on at a chemical level in nature. Here is a common plant, growing in mucky wetlands, that uses carbon, hydrogen, oxygen, and energy from the sun to make food, chemical weapons, and pharmaceuticals.

And the amazing talents of marsh marigolds go even further. Even a glimpse of their sunny blossoms brings a smile to my face, causing the release of endorphins and serotonin in my brain, and the end of my dreary wet grumblings. How wonderful is the chemistry of nature!

Author’s Note: This article was originally published in 2013. 

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and to see what we are up to.