The Chemistry of Nature

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!

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI, at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April, 2014.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.

Little Packets of Fatty Goodness

After you notice one, you start seeing them everywhere. Despite the chilly breeze and gray skies, my eyes never stopped scanning the dry brown leaf litter as we hiked up the trail to St. Peter’s Dome. Last year at this time, our Spring Wildflower Hike revealed a lush jungle of blooming, buzzing, growing, greening plants. The earliest bloomers, like spring beauty and Dutchman’s breeches were already past, except in chilly microclimates.

On this day, I exclaimed in delight at the tiny crimson petals thrusting out of the bud on a beaked hazelnut twig. A single leatherleaf shrub in bloom with delicate yellow flowers brought similar excitement. Then, when I noticed the first tightly furled spike of trillium leaves that had worked its way up through the dry maple leaves, I was ecstatic.

The group stopped with me to search for more, and as our eyes adjusted, our mental search images honed, and the tiny green spikes appeared everywhere. Although we could not identify the spikes, we knew from last year that these could be wood anemone, large-flowered trillium, violets, Dutchman’s breeches, and bloodroot. The fully unfurled leaves of spring beauty, just over an inch long, clustered in the shelter of a fallen log.

These spring ephemeral wildflowers have figured out that they can make use of the rich soil in the shady depths of deciduous forests, so long as they get a head start on the trees. In part because they only show up for such a short time each spring, they have captured many a heart.

In particular, many of these flowers have a close, symbiotic relationship with ants. You don’t see it now, but in a month or so, when they are done blooming and have gone to seed, a soap opera emerges. All the wildflowers I listed above attach a packet of fatty goodness, like a donut for ants, to the outside of their seeds. Called an elaiosome, this little bit of energy-rich lipids, amino acids, and other nutrients, shows that the way into an ant’s hill is through its stomach.

Ants carry the elaiosome, still attached to its seed, down into their hill. There the ants may feed it to their larva or eat it themselves. The seed, which is smooth, hard, tough to hold on to, and impossible to eat, is thrown into the ants’ midden or garbage heap. Here, in a nitrogen- and phosphorus-rich environment, among moist, decaying plant matter and the bodies of dead ants, the seed has a wonderful place to grow. It is safe from birds, other insects, and even forest fires. This type of ant-assisted seed dispersal is called myrmecochory.

Myrmecochory (mur–me-co-cory) is exhibited by more than 3,000 plant species worldwide, and is present in every major biome on all continents except Antarctica. One study determined that it has evolved at least 100 separate times in 55 different plant families.

In nature, when there is success, there is often a cheater. Hepatica, a beautiful purple or white spring ephemeral flower that emerges before its leaves, is an unassuming swindler. Instead of providing a detachable treat for the ant, hepatica just covers its seed in a non-removable elaiosome with the same chemical cues as its neighbors’ true elaiosomes.

When ants take hepatica’s seeds back to the nest, the elaiosome can’t be eaten, and the chemical cues stay intact. Instead of being stripped of its packet of fatty goodness and thrown in the trash heap, the hepatica seed stimulates each ant that passes by to pick it up by the permanent, fatty handle and carry it somewhere else. Hepatica saves energy by not making a large elaiosome, and it benefits when its seeds are distributed more widely. In return for their dispersal services, the ants get nothing. Hepatica is a parasite!

If cheaters win, though, then pretty soon everyone starts cheating. For a mutualism (a symbiotic relationship where both parties benefit) to continue, it must provide appropriate rewards. Scientists have found that seeds with true, tasty, edible elaiosomes are transported by ants much more often than the cheater seeds of Hepatica and others like it. “In this situation, cheating … establishes a background against which better mutualists can display competitive superiority, thus leading…to the reinforcement of the mutualism (Pfeiffer et al, 2009).”

Such drama, on what may seem like a small scale, impacts entire ecosystems on six continents. In this northern hardwood forest, maple leaves cushioned my knees as I crouched down to get look closer at the just-opened flowers of Dutchman’s breeches. A bit of movement caught the corner of my eye, and I shifted my focus to a patch of soft moss. A tiny black ant was scrambling its way across a jungle of leaves. As my gaze widened, I noticed another ant, and then another and another, all busy with their own lives. After you notice one, you start seeing them everywhere.

The Smell of Rain

Throughout the morning, the fluffy white clouds grew larger and more numerous, cluttering up the blue sky. The temperature on the bank sign rose sharply from 40 degrees in early morning, up to 77 degrees by early afternoon.

After lunch, I stepped outside to run errands. A blast of hot, humid air washed over me as I opened the door. We just finished winter with a blizzard, and now it is summer! Then the rain began to fall. I stood under the overhang and watched as huge, splashing, cold drops plunged down through the warm air. Now it not only felt like summer, it smelled like summer.

You have probably smelled it, too: that sharp, pleasant, green scent of rain on dry earth. Those same wonderful odors will even rise up from concrete and asphalt. This smell has a fancy name, and also a biological explanation. The name is “petrichor,” which comes from the Greek word for rock (petra), and their word for the fluid that flows in the veins of the gods in Greek mythology (ichor). You are smelling the blood of the gods sprayed up from the rocks. It is defined as "the distinctive scent which accompanies the first rain after a long warm dry spell."

This wonderful word was coined in 1964, by Isabel Joy Bear and R. G. Thomas, two Australian researchers who discovered that the scent originates from an oil which plants produce during dry spells to retard seed germination and early plant growth. This may be an adaptation plants use to limit competition during times of low moisture. Rain washes the oil away, stimulating germination and growth again. During the dry spells, the oil may also be absorbed into rocks and soils. Falling raindrops liberate the compounds from both plants and rocks, and fling them into the air we breathe.

The rain tapered off, and I walked down the street on my errands. From the bare soil in expectant flower gardens, another scent rose up to meet my nose. This earthy aroma is characteristic of healthy, post-rain soils, and sometimes is even included in perfumes. The name for this scent, “geosmin” also has a Greek origin (combining the words for earth and smell) and a biological explanation.

Geosmin, an organic compound, is produced by several classes of microbes in the soil, including cyanobacteria (blue-green algae) and actinobacteria (especially Streptomyces, which are important to medicine as a source for antibacterial and antifungal agents as well as anticancer drugs). The organisms thrive when the conditions are damp and warm, and create geosmin as a byproduct of living. In an effort to reproduce before they dry out, the bacteria also release geosmin-scented spores. Rain flings these compounds into the air, just as it does with petrichor, and we smell “earth.”

Smelling that wonderful earthy smell is one thing, but tasting it is quite another. Beets, some wines, and bottom feeding fish like catfish and carp all derive their characteristic earthy flavor from geosmin. Some folks like it, and others don’t. Even the water we drink can be tainted with the flavor, though it will not hurt you. Human taste buds are very sensitive to geosmin, and the average person can detect it at a concentration of 0.7 parts per billion. The human nose is even more sensitive, and is able to detect geosmin at concentrations as low as 5 parts per trillion.

In deserts, the presence of geosmin usually indicates water. Camels may follow the scent to an oasis, and then disperse the spores to new places on their travels. Some cacti scent their flowers with geosmin, thereby attracting thirsty insects who are tricked into serving the plant as pollinators. Closer to home, some biologists suspect that petrichor, washed into streams by rain, signals spawning time for freshwater fish.

In Australia, aboriginal people associate geosmin with the first life-giving rains of the wet season, and with the color green. So important is this smell that geosmin perfume, rubbed onto their bodies, serves as a symbolic connection of body and landscape. According to research done at the University of Queensland, “The odor is believed to be protective and cleansing, linking present generations to their ancestors.”

Rain is grace; rain is the sky descending to the earth; without rain, there would be no life. -- John Updike

Without rain, we could not smell petrichor, geosmin, the blood of the gods, the scent of the earth, the link to generations past. Without rain, we could not smell summer.

Soon the clouds thinned and dispersed, the pavement dried, and the sun shone. The smell of summer lingered on the breeze, and lilac buds began bursting with green in their effort to catch up!

The Tribes Wake Trilling

“You think it will never happen again. Then, one night in April, the tribes wake trilling.”

The first time I read this line from Mary Oliver’s poem, Pink Moon—The Pond, it thrilled me to the core. You may have felt that excitement, too, as you stepped outside to view the moon or let in the dog and were drenched by the music of frogs singing their hearts out in the cool, wet darkness of spring. The wood frogs are often first, with a series of sharp quacks, almost like a duck. Spring peepers live up to their name with high-pitched peeps. Enough peepers shouting at once sounds almost like sleigh bells. Then there is the “crrreek,” of the western chorus frog, that approximates fingers running over the teeth of a comb.

Why do the calls of amphibians give us such a thrill? Perhaps because it is a sure sign that spring is coming. Or maybe we sense their joy at being animate after a winter of being frozen solid. It might also be that we can feel the urgency in their voices as the males try valiantly to attract a female and procreate before the next guy steals her.

Frogs aren’t the only ones trilling this time of year. Yellow-rumped warblers and pine warblers are two early migrants with their own sort of trilling calls. In my college ornithology class, we decided that pine warblers sound like a UFO landing, and the yellow-rumped warblers have a much more variable call. Birdjam.com has excellent recordings of both. They have both arrived back in the northwoods, so listen up!

Frogs and warblers are exciting signs of spring, but on a recent evening, it was another call that pierced right through my window. “Old Sam Peabody-Peabody-Peabody,” whistled the white-throated sparrow. Instantly, a flurry of memories swirled around my brain like snowflakes in April.

As a sophomore in college, I had the opportunity to be the teaching assistant for a literature course called “Pens and Paddles in the Northwoods.” We were to spend 15 days in May paddling in the Boundary Waters and reading Thoreau, Olson, and Jaques. I had never been that far north in the spring. My parents, who spent their honeymoon in the Boundary Waters, later traveled there for 100 days, and “dated” during ornithology field trips in college, were ecstatic with anticipation for me to experience it as well.

One evening during spring break, as I was home borrowing gear, my dad went to the box of old records (you know, those round black things that play music), and selected one to put on the turntable. He checked the track list, and placed the needle carefully. Suddenly, the piercing cry of “Old Sam Peabody-Peabody-Peabody,” filled the room. “Listen for this,” he said. “You can’t miss it…this is the sound of spring in the North.”

Listen I did. Through swirling snowflakes, cresting whitecaps, dismal rain, and mucky portages, the white-throated sparrows sang us on with unceasing vigor. It was a tough trip during a cold spring, but somehow, being able to identify that bird call renewed my self-confidence each time I heard it.

I have since spent many weeks in the Boundary Waters, and sometimes the white-throated sparrows called with such intensity in the spring that I pleaded with them to give us some peace and quiet. Nowadays, with a full-time job, I don’t get up to canoe country until August, and all I hear are the abbreviated calls of late summer. White-throated sparrows do breed in northern Wisconsin, but I don’t hear them as much here.

It is snowing again today, and I could have started yet another article with a skiing adventure. But it’s May now – and I’m pretty sure you would rather read about frogs and birds.

You might be wondering how all these trilling tribes fare when the weather changes so quickly. There is certainly some mortality, but the frogs can accumulate sucrose (sugar) in their bodies. The sucrose concentrates fluids, and reduces ice crystal formation. Since they can freeze solid without harm for three or more days, this quick cold spell shouldn’t be a concern.

Even though the birds prefer summer temperatures, they always carry their own down jackets. Cold is not an issue, as long as their metabolism has enough fuel. The yellow-rumped warblers glean tiny insects off twigs, and may still be able to find enough food with a foot of snow on the ground, but the white-throated sparrows, who are ground-feeding seed-eaters, will now have a harder time.

Soon spring will really come, however, and all of us will sing a little louder.

“You walk down to the shore. Your coming stills them, but little by little the silence lifts until song is everywhere…”

Plus, looking on the bright side, there is one trilling tribe that has not woken up yet – mosquitoes!

For over 45 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April, 2014.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.

Desert Adaptations in the Northwoods?

A vivid blue sky stretched overhead as the intense spring sun rose above the twiggy treetops. The thick blanket of fresh, white, snow reflected bright rays up and under the brim of my cap. Ski tracks that had been crunchy with ice just 30 minutes ago were now softening as the temperature rose steeply from a nighttime low of 18 degrees, to a daytime high of 45. The one thorn in my day was an uncomfortable crack in the winter-dry skin of my left heel.

It was amazing to be skiing in late April, in Wisconsin, and it is amazing that I can begin yet another Natural Connections by describing an experience on the ski trail. This particular day, with its bluebird sky, bright sun, and warm temperatures, also reminded me of another spring ski in a faraway land called Utah.

Back in 2005, I did an internship with the National Park Service leading school field trips and working in the visitor center in the Needles District of Canyonlands National Park. I lived in the tiny little town of Monticello (very similar to Cable!) at the base of the Abajo Mountains. Even though their name means “low,” the mountains tower above the intricately carved sandstone canyons of the park.

One weekend, my roommate and I took our skis and drove up the mountain road to where the snowplows stopped. From there, we skied up and over the snow-packed pass, and stood breathless at the view. From the midst of winter, we looked out on a sunbaked summer landscape of red rock canyons below fluffy white clouds. The view fueled our anticipation for spring. The only thorn in my day was cracked lips from the desert-dry air.

You might not think that Wisconsin and the desert southwest have much in common, but I found enough similarities in Utah to feel at home there, too. The snow, for one, was a nice connection. And half-buried in that snow were manzanita bushes with small, waxy, evergreen leaves on short woody stems. They bore a family resemblance to their cousins, other plants in the family Ericaceae, who are some of my favorite residents of Wisconsin bogs.

If you’ve ever explored a bog, you may have noticed that quite a few plants have those small, waxy evergreen leaves. Leatherleaf’s name advertises its tough appendages, while the lovely names of bog rosemary, bog laurel, small cranberry, and snowberry contrast with their hardy leaves. All are in the Ericaceae family.

Down in the desert canyons, the fuzzy leaves of sagebrush, Indian paintbrush, globemallow, and the in-rolled leaves of mountain mahogany also reminded me of my Wisconsin home. That might seem odd, but have you looked at the underside of a Labrador tea leaf from your local bog lately? The leaf margins roll in on a dense patch of wooly orange hair, and hairs also carpet the tightly-curled leaves of its neighbor, bog rosemary.

Why might desert plants and bog plants have some characteristics in common? For one thing, they both deal with a lack of water and desiccating winds during at least part of the year. But aren’t bogs soggy? Well, yes, but not when they are frozen, a condition that can extend late into spring. Plus, sometimes the peat in bogs builds up so much that plants are elevated above the water table. Deserts and bogs are also poor in nutrients due to slow decomposition rates.

Evergreen leaves are great for contending with low nutrient availability and short growing seasons, because plants do not need to grow new leaves each year, so they are less dependent on nutrients getting recycled. However, unlike deciduous leaves, evergreen leaves must deal with the absence of liquid water in winter (or in the summer for that matter.) The thick, waxy cuticle is a plant’s first defense, since it reduces water loss from evaporation. It serves the same purpose as the beeswax-based salve I massage into the cracked, dry skin of my heel and lips. This protective wax is as useful in Wisconsin winters as it is in Utah!

Although waxy leaves help protect them from drying out, plants still need to exchange some gases through their stomata to carry out photosynthesis. Stomata are pores in the leaf that allow gas exchange. Along with taking in the carbon dioxide necessary for photosynthesis, water vapor can also escape during transpiration. To reduce this loss, plants – both here and in the desert – try to create a “boundary layer.”

The boundary layer is a thin zone of calm air hugging the surface of the leaf. In this layer, the conditions are less harsh (less hot and dry) than in the wider world, and the temperature and moisture gradient is less steep. Therefore, the larger the boundary layer, the slower the rate of water loss. Hairy and in-rolled leaf margins increase the size of the boundary layer and slow water loss from transpiration. Humans create our own boundary layers with fuzzy wool sweaters and fleecy mittens.

Today we stand in Wisconsin – on the edge of winter – admiring the view of a distant spring. Although it may look quite different from southeast Utah, similarities can be found across all communities if we are willing to look a little closer. This holds true in our human communities just as much as in our natural communities. Where can you see our own Midwestern toughness and resilience reflected around the globe?

“It is a wholesome and necessary thing for us to turn again to the earth and in the contemplation of her beauties to know of wonder and humility.”

--Rachel Carson

Change

For the past few weeks, I enjoyed writing about things I had been mulling over for months. First, it was instinct and faith. Spring is a time of rebirth and renewal for almost everything, and organisms follow age-old clues to schedule their spring events. As we all wait for the relative ease of summer, looking to the sky can be a comfort no matter what you believe is up there.

Then I got philosophical about wind, and how it is both a symbol and a source of unity, freedom, eternity and balance. Most importantly for this time of year, the wind is the Earth’s attempt to find a temperature balance.

Recently, I shared stories of the many amazing organisms (including humans!) that look forward to the maple sap run each year. You can find all these stories on our Facebook page, or our blog at http://cablemuseumnaturalconnections.blogspot.com/.

All the while I was writing, something else was gnawing at my brain as well: an unpleasant, but fascinating understanding of how these three topics, and many others, are connected to each other, and to our actions.

Last year, UW-Madison professor Steve Vavrus and a colleague at Rutgers University published a paper hypothesizing that warming in the Arctic would cause the jet stream to slow down and meander like a river flowing through the plains. This, in turn, transports less warm air from the oceans over the land, and sets up more extreme weather.

The big-picture mechanism for this connection between warm oceans and slow-moving/extreme weather is not too hard to understand. Wind moves from high pressure to low pressure and equalizes temperature differences. When the temperatures are not as different, the wind does not have as much oomph. Melting ice in the Arctic, Professor Vavrus explained, allows heat stored in the ocean to escape to the atmosphere where it changes the pressure patterns.

It came as no surprise to the scientists, then, when record-low sea ice coverage in the Arctic last summer was followed by the coldest March in Wisconsin in 35-40 years, and a cold April full of slow-moving blizzards. Professor Vavrus acknowledges there is some natural fluctuation of the circulation patterns, and that weather and climate are different things, “But we're arguing the loss of sea ice is ... loading the dice in favor of a more negative Arctic oscillation pattern.” It is loading the dice in favor of extreme, unusual, and sometimes unpleasant weather.

The same meandering jet stream, he noted, could also explain the unusually warm spring in 2012. If a meandering jet stream is like a river, some bends are favorable to cold spells; others are favorable to extreme warmth. Either way, these unusual weather patterns are symptoms of climate change.

While we might be frustrated by the snow this spring, last spring people preparing to tap maple trees were just as disappointed by the early heat wave that severely shortened sap season. Cold nights are necessary for strong sap flow, and early bud-break stops it.

Wisconsin is one of the highest sap-producing states, and the crop value of syrup can be over $5.8 million a year. The value of this ancient tradition in terms of cultural history is immeasurable. You can read more at www.climatewisconsin.org.

This year, reports from tappers both old and new all point to the fact that this is just a weird year. As temperatures fluctuate from warm enough to cold again, the sap starts and then stops flowing. High winds steal away heat that trees absorb from the sun, slowing sap flow. Some sugarbushes are reporting record sap flows already, while others have not even started.

Maple trees respond to temperature to cue their sap flow, but other organisms rely on day length and sunlight intensity to prompt spring events. Many creatures in each category rely on each other for food, pollination, or other symbiotic services. What happens, then, when the day length and the temperature do not match up like the creatures expect? Will their faith in the progress of spring serve them well? Or will old instincts not work in a changing climate?

These are heavy questions to ponder, as I trudge through the slush with sleet pelting my face. The balance brought by wind, the comfort of the sky, the renewal of spring…will these change, too?

For over 45 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The current exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.