Thursday, September 24, 2020

Point Your Beam of Curiosity at the Universe

Room by room, I went through the house gathering supplies and turning off lights. Finally, only the string of Christmas lights that I use as a nightlight by the front door remained. Cool air brushed my cheeks and a breeze sighed through the pines as I slipped yellow-lensed safety glasses over my eyes. Anticipation bubbled up. With a click, the heavy flashlight in my hand turned on, and a new world appeared. 

As I swept the beam back and forth across my yard, I was stunned to see that many leaves looked deep red. This isn’t an ordinary flashlight: it’s a V3 Black Light UV Flashlight from the brand uvBeast. They didn’t pay me to mention that, but I know some of you would want to know.

My first encounters with the magic of black light were in the back corner of Spencer’s Gifts on rare shopping trips to the mall. My white t-shirt glowed, along with the psychedelic posters of magic mushrooms and Grateful Dead bears. Cool, but not really my style.

Then, in early 2019, scientists at Northland College published a paper describing how flying squirrels fluoresce hot pink in UV light. That type of surprising science IS my style, so as I developed the Cable Natural History Museum’s “Mysteries of the Night” exhibit (which opened on August 4), I ordered a fancy UV flashlight and dreamed up ways to use it. Now that the mosquitoes are dead and darkness is falling before my bedtime, it finally made sense to take my new toy out for a night hike. 

Gravel crunched under my feet as I headed down the driveway. I soon discovered that red leaves were everywhere, but not every leaf was red. This was especially puzzling in patches of moss, where some tufts remained green. Green is, of course, the normal color of a leaf in daylight. That’s because chlorophyll within the plant cells reflects green light back to our eyes. The chlorophyll also absorbs the violet, blue, and red wavelengths of light and then transfers most of their energy to other molecules for photosynthesis. Some of the absorbed light is re-emitted in a lower energy state—which also means a different color. 

Ultraviolet or black light is very high-energy. The destructive power of UV light can be harnessed to kill bacteria and viruses, but it can also damage our eyes if we’re not careful. That’s why we wear UV protective sunglasses during the day, and why I was wearing safety glasses with yellow lenses for this black light adventure. It is also why we experience “snow blindness:” the cornea of the eye becomes temporarily cloudy to prevent excess UV from burning the retina. About 10% of normal sunlight is in the UV range.

So, when I shined my fancy flashlight at the leaf, the high-energy ultraviolet wavelengths were absorbed and re-emitted as lower-energy red light. This re-emitted light is called fluorescence. The process is impacted by the health of the leaves. In fact, scientists measure chlorophyll fluorescence to help detect many types of stress in plants, like the early stages of an infection; or drought. Remember when I mentioned that some mosses were red and others didn’t seem to fluoresce? As far as I could tell, it was the happy, well-moisturized mosses who fluoresced, and the dried out specimens who didn’t. 

My flashlight didn’t just illuminate blood-red plants. A blue-white glow in the leaves revealed a mushroom hidden beneath the duff, and a millipede crawling over it. The tiny blobs of a slime mold (appropriately named tapioca slime mold—that should help you picture it) shimmered in a weird shade of greenish white. Grasses looked blue due to the properties of ferulic acid bound within their cell walls. A small patch of lichen on a tree trunk—a species who I know is usually drab gray—glowed orange. In one patch of happy red moss, a tiny grub shone brilliantly as it wiggled around, its digestive tract visible within its translucent body. 

As I crawled along the high, mossy bank of my driveway, my beam of light illuminated wonder after wonder. The lives I thought I knew were transformed by this new way of seeing. 

A light mist began to fall, so I headed back inside. Room by room I went through the house, putting things away and getting ready for bed, until once again I’d turned out all the lights.

When I awoke the next morning, the headlines were all about signs of life on Venus. Did you read about this, too? Jane Greaves, an astronomer at Cardiff University in Wales, pointed a telescope at our neighboring planet and used radio waves to identify the molecules swirling around its atmosphere. She found relatively high levels of phosphine, which is a chemical often produced by tiny organisms who don’t use oxygen. Is there life on Venus? It’s too early to tell. 

What I can tell is that wherever we choose to point our beams of curiosity, they inevitably illuminate something new and wonderful. And if you ask me, that says more about our universe than our aim.

Crab Nebula
Credits: NASA, ESA, J. Hester and A. Loll (Arizona State University)

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

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 brand-new Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and to see what we are up to.

Thursday, September 17, 2020

The Ash Tree Mystery

I’ve always loved a good mystery. It probably started with The Boxcar Children books. Those mysteries aren’t about murders. They contain just the right amount of delicious suspense without being scary, and often I learned something from those books outside of my normal experience, too. The mysteries I read these days are about nature, whether in a book or in the wild. And recently, I’ve been seeing something mysterious in the woods. 

Now that the cold weather is triggering trees to draw green chlorophyll back into their twigs, their yellow and orange pigments—always present—are suddenly visible. After swamp maples and other occasional stressed out trees, black ash trees are the first to show fall colors. Black ash swamps are currently a warm shade of gold, and provide a cheerful place to gaze while the clouds are gray and heavy. In among those sunny leaves, though, are scraggly, dark brown clumps about the size of a softball that I’ve puzzled about off and on for years. 

Black ash swamps show their colors in early fall. Photo by Emily Stone.

Are they clumps of seeds? Well, no. Ash seeds do hang in clusters, but they take the shape of little, oblong samaras—winged seeds like maple helicopters—that change from pale green to straw-colored (not dark brown) as they ripen. 

Are they clumps of dead leaves? It’s not that, either. Sometimes I do see ash trees where their leaves haven’t fallen off completely, but there aren’t scraggly clumps left behind; there are just elegant, yellow-green leaf petioles. 

On a recent kayak trip down the Namekagon River, I spotted an ash tree with the mysterious clumps, and since I was paddling next to a forester, I pointed them out. “Well, you know,” she said, “individual ash trees are either male or female.” I didn’t know that! We reasoned that since the female trees would be producing the seeds—which look different than these clumps—these would most likely be the male flowers. Now I had a lead, and I brought it back to Google.

At first, the photos of male ash flowers that popped up just looked like small, maroon pompoms tipped with pollen, and that wasn’t helpful. But as I scrolled through the images, a brown clump appeared, and I followed it through to a blog post about ash flower galls. Of course. I should have guessed. The clumps are caused by critters!

The male flowers on black ash trees are transformed into scraggly brown masses by a microscopic mite. Photo by Emily Stone. 

Ash flower gall mites (Eriophyes fraxinivorus), look like translucent walruses. At only 2/100 of an inch long, however, they are not visible to the naked eye. All winter, fertilized female mites hang out on ash twigs, sometimes even crawling inside the fuzzy brown scales that protect the flower buds like a warm winter jacket. Come spring, the mites feed and lay eggs on the developing flowers. As with any gall, the feeding action stimulates the plant to grow around the interloper. On a goldenrod stem, for example, a fly larva creates a globe-shaped gall. 

These ash flower gall mites cause a much more messy reaction. Under the mite’s influence, flower stems grow longer than normal, and even fuse with their neighbors. Everything curls, twists, branches and fringes, and forms a broccoli-like mass. Several generations of baby mites called nymphs find food and protection within the gall over the course of the summer. 

In September, the green gall turns into a woody, brown clump, and suddenly I start noticing and pondering this mystery all over again. Once dry, the galls may remain on the tree for a couple years, and can be unsightly, but won’t cause the tree much harm. 

Galls are a widespread example of a symbiosis, where two different species have a close living relationship. I’ve written about oak apple galls, goldenrod galls, willow pine cone galls, willow rose galls, and aspen leaf galls—they’re all fascinating! 

So, mystery solved, and yet another story about a gall added to my list. Maybe The Boxcar Children should add this one, too, and call it: “The Ash Tree Mystery.”

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

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 brand-new Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and to see what we are up to.

Thursday, September 10, 2020

Little Packets of Fatty Goodness—New Research

On a humid morning in late July, I found myself hiking the steep trail to St. Peter’s Dome with an energetic family and a swarm of mosquitoes. I remembered fondly back to my early spring hikes—when the wildflowers were in full bloom and the bugs had not yet hatched. 

I interrupted my own reverie when I spotted a little green capsule dangling among the graceful leaves of a large-flowered bellwort. Last May, I’d stopped several times to photograph this plant’s sunny yellow petals, and here was the next step: a pod full of seeds. 

The seams on the 3-sided pod were already bursting, an action which botanists call “dehiscence.” As I cradled the opening pod, tiny seeds landed in my palm. With cream-colored faces and tiny white wigs, they could be the start of some miniature George Washington dolls. Actually, though, the wigs are little packets of fatty goodness called elaiosomes. I like to describe them as donuts for ants. 

The seeds from large-flowered bellwort are topped with appendages to attract ants. They also remind me of George Washington in his wig. Photos by Emily Stone. 

Back in 2013, when I first learned and wrote about elaiosomes, the most popular hypothesis was that the flowers were bribing the ants to carry their seeds into anthills, where they would be discarded on a compost heap—well-fertilized and out of the reach of hungry birds and raging wildfires—to grow. Other hypotheses are being tested as well. Recent research highlights other nuances of the relationship between ants and plants. I called three of the scientists doing that research to find out more. 

Dr. Chelsea Miller, who recently earned her PhD from the University of Tennessee in Ecology and Evolutionary Biology, did some field work that sounds lovely. First, she went out in early spring, when all of the Trilliums were gorgeously in bloom, and flagged 30 individuals of a few different species. Then, she went back in late summer when their seeds were almost ready to dehisce, opened the pods a tad early, and put the seeds out on a “seed depot,” which is a fancy way to say a place that ants can get to that also allows scientists to keep an eye on the seeds. Then she sat down, set a timer for an hour, and waited. 

Chelsea Miller studied how ants disperse the seeds of Trillium flowers for her PhD research. Provided photo.

As you can imagine, Chelsea saw more than ants. “I had a lot of quiet time to myself in the woods,” she told me. “It’s kind of a gift.” An oblivious deer wandered by, interesting birds grew used to her presence, and once a bear showed up. Chelsea also saw (about half the time) one or more ants arrive at her depot, pick up a seed by the grippy elaiosome, and carry it off. She then followed the ant until it dropped the seed or arrived at its nest, and measured that distance—usually only a couple of meters or so. 

Chelsea observed that seeds from common and widespread species of Trillium seemed to attract more attention from ants than their more rare Trillium cousins. Using mass spectrometry, she confirmed her hypothesis that the elaiosomes of the widespread species contain more of the nutritious oleic acid than the rare species of Trilliums she tested. The conclusion is one any entrepreneur can understand: flowers are more successful when they make more desirable donuts for ants. 

The capsule from a Trillium flower splits open to reveal brown seeds with white elaiosomes. These attachments provide ants with nutrients in exchange for transport, but new research points to additional complexities in that relationship. Photo by Emily Stone.

We can watch as an ant removes an elaiosome and either eats it or feeds it to the colony, but what if the ant is adding or subtracting things from the seed that we can’t see? Dr. Chloe Lash, who just earned her PhD from the same lab as Chelsea, studied how ants impact a seed’s microbiome as they handle it. Microbes are living things like fungi and bacteria who we can’t see with our naked eye. 

In order to do the study, Chloe made a pool of the microbes, extracted DNA, and put the samples through a machine that sequenced the DNA. This told her who all was there and their relative abundance. She analyzed the microbiomes of bloodroot and wild ginger seeds straight from the seed pods; after ants had handled them; and after she had removed the elaiosomes herself. As predicted, the microbiomes changed. Ants not only removed the elaiosomes, they also removed several potential pathogens from the seeds and altered the entire microbial community.

The seeds of bloodroot contain elaiosomes AND a microbiome of fungi and bacteria. After an ant removes the elaiosome, the microbiome is altered as well! Photo by Emily Stone.

One day, while Dr. Kirsten Prior, now a professor at Binghamton University (SUNY), was watching her own seed depots for signs of ants, a slug crawled by and scraped the elaiosome off one of the seeds. At first she was just annoyed at its interference, and then, as science often works, she decided to study the slug. In Europe, native slugs eat whole seeds to get at the nutritious elaiosome, and then poop out the seeds where they can grow. This non-native slug who Kirsten observed just stole the donut and left the seed where it lay, interrupting its dispersal. 

Why should we care about nefarious slugs? Ants disperse the seeds of 30-40% of our understory plants, including many of the beautiful spring wildflowers who are disappearing. There are other invasive villains out there, too. Non-native earthworms seem to displace ants. In other places, non-native ants may be changing how and which seeds get moved around. 

During the interview, Chelsea told me that “The most exciting thing is how much we don’t know!” These scientists have made interesting discoveries about relationships that are integral to our ecosystems—and that impact our favorite wildflower woods. They’ve also made it clear that we have much more to learn. I, for one, learned that sometimes it is worthwhile to take a walk in the woods…even during mosquito season.

Nodding trillium seed capsule. Photo by Emily Stone.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

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 brand-new Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and to see what we are up to.

Thursday, September 3, 2020

Award Winner: Beaver Costume

(I’m thrilled to announce that this article won 2nd place in the Newspaper/Family Participation-Youth Outdoor Education category of the Outdoor Writers Association of America’s 2020 Excellence in Craft Contest! It’s a little bittersweet to post it just as school begins, since our MuseumMobile lessons are moving to a virtual format during the pandemic.)

“Are you going to dress someone up like an animal again?” asked an eager fifth grader at Drummond Elementary this week. I’d called on the student with his hand up because I was hoping that he’d answer the question I had just asked: “What do you remember learning on my first two visits to your classroom this year?” 

Jane Weber, our MuseumMobile Educator, recently developed three new lessons for our fifth grade classroom visits. In the fall, students learned about white-tailed deer, and practiced deciphering a deer’s age by the teeth in cleaned jawbones. For our winter visit, we dressed two students up like fish, and compared the adaptations of prey fish (sharp spines, laterally compressed bodies, and eyes on the sides of their heads) with predator fish (sharp teeth, torpedo shaped bodies, and eyes on the front of their head). 

Now, for our spring lesson, we were about to learn about beavers. Like all animals, beavers have an impressive suite of adaptations that help them survive in their habitat. As teachers, Jane and I have adapted to a 5th grader’s sense of humor, and designed the lesson around dressing a kid up like a beaver.

I started with the feet. Beavers’ hind feet are webbed, of course, to help propel them through the water. Oddly, they also have a split nail on their second toe, which acts like a comb for spreading oil throughout their fur and removing debris. That oil is very important to beavers as they swim underneath the ice all winter long. Without it, they would be wet and chilled to the bone. So, after fastening two giant foam webbed feet around my victim…er volunteer’s ankles, I also handed her a photo of an oil can.

Two brown gloves went on next. Beavers have surprisingly dexterous hands that they use to bring mud to their dam and lodge, to hold twigs while eating, and to dig out deeper channels for swimming. 

The class roared with laughter when I pulled a fancy faux fur jacket out of my tub. These students have been growing up in our MuseumMobile program since they were in pre-K, and some of them remembered feeling the soft pelt of a beaver in their early years. One girl gazed off into the distance as she described the soft, warm underfur of her memory. Another piped right in to tell me about beavers’ longer, shinier guard hairs that help shed water. 

Jane had sneakily sewn a strip of Velcro under the back hem of the jacket. To this, I affixed a giant, flat, brown beaver tail, which also got a laugh. I also pulled a real (dried) beaver tail out of my tub to show around the class. They’d also seen this in kindergarten, but beaver tails never get old. Of course one kid peered at the cut end and exclaimed in disgust. Beavers use their tails for fat storage, and the now desiccated fat isn’t exactly pretty. But it was useful when the beaver was alive. That fat fuels their metabolism during the long winter to help them stay warm. 

The students easily came up with three more uses for a beaver’s tail: swimming rudder, warning signal, and a kick-stand to help them balance when cutting down trees. Their tails also help beavers dive quickly under the surface, and help them stay cool in the summer. One thing that a beaver tail isn’t useful for: patting mud onto their dam and lodge. Only cartoon beavers do that. 

Before handing our beaver her Mardi Gras-style mask on a stick, I brought out a real beaver skull. This isn’t the first time these students have seen that exact skull. It’s neat to provide continuity through the years. In kindergarten they have their first introduction to beavers, admire the skull, and feel the stick that’s been de-barked by a beaver’s teeth. In second grade we bring out the beaver skull to illustrate how the teeth of an herbivore differ from that of a carnivore. In fourth grade, when we dissect owl pellets and find lots of little mouse skulls, I show the beaver skull as a bigger example of a rodent’s orange front teeth. 

Today we look more closely at the skull, and talk about the iron that stains the teeth orange, giving them added strength. We also note that the eyes, ears, and nose of a beaver are all sitting right at the top of its head. Even while swimming with their body completely submerged, beavers can have all of their senses attuned to danger. 

Before I hand our volunteer her mask, I ask the kids how many of them use goggles for swimming. Beavers have built in googles, I tell them, and of course we’re all jealous. I’ve never met a pair of goggles I like. But beavers have a third, clear eyelid, called a nictitating membrane. It protects their eyes from debris while they swim. I show the class a clear plastic lens covering the eyes of our beaver mask, then hand it over to our busy beaver. 

The last prop is a pair of ear muffs. Water in your eyes isn’t the only issue. Beavers have valves in both their ears and nostrils to keep the water out while diving. Now we’re all seriously jealous, as we commiserate over how terrible it feels to get water up your nose or stuck in your ears while swimming. Beavers may look a little odd, but they have some sweet tricks up their fur. 

Our completed beaver now spins slowly to show off her adaptations, and we applaud her cooperation before dismantling the costume. 

Then I pass out bingo cards filled with pictures of animals. The dams that beavers build, and the ponds that fill in behind them, are incredibly valuable habitat for countless species. I start calling off animals that rely on beavers: songbirds, wood ducks, kingfishers, mink, dragonflies, great blue herons, deer, pileated woodpeckers, and water lilies. At this point, the entire class is on their edge of their seats, just needing one more square to win. Of course, I’m chuckling to myself, because I designed three different bingo cards that would all win at the same time. “Leopard frog!” I call, and the class erupts. 

As I clean up my supplies and wrap up the class, I’m still chuckling to myself. “Bingo!” I think to myself. Jane did a great job designing a lesson to teach fifth graders about the amazing adaptations of beavers. 

(Check out the virtual version of this lesson I created last spring! )

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at Or order it from our friends at to receive free shipping!

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 brand-new Mysteries of the Night exhibit. Connect with us on Facebook, Instagram, YouTube, and to see what we are up to.