Dynamic Earth at the Market

by Kevin Theissen


Our planet is a dynamic, ever-changing system and this past Saturday at the market we explored the fascinating science of geology with a team of students and faculty from the University of St. Thomas.   Geologists use physical models to understand the natural behavior of streams like our local Mississippi River. The models provide insight on major processes such as erosion, transport, and deposition–and the sometimes hazardous consequences which include flooding and landslides. Visitors got hands-on experience investigating the interactions between water flow and landscape with a table-top stream table. They created hills, dams, slopes, and stream channels and experimented with changes in the rate of streamflow. Visitors learned that the “sediment” for our stream table was an unexpected material—recycled toilet seats!



The Earth’s large crustal plates move at the rate that our fingernails grow and accordingly lead to much slower changes than rivers. Given hundreds of millions of years, however, those slow changes mean dramatic differences.   Visitors observed marine fossils of organisms known as brachiopods, bryozoans, and crinoids representing a shallow tropical sea that once covered the Twin Cities and much of southeastern Minnesota during a period of geologic time known as the Ordivician, more than 450 million years ago. Reconstructions of plate movements suggest that Minnesota was likely centered on the equator during this time.


Visitors also donned 3-D glasses to get dramatic views of a variety of important plate tectonic settings where plates converge, spread apart, and slide past each other.   Perhaps the best example of this is the Pacific ‘Ring of Fire’ which includes deep-sea trenches, mid-ocean ridges, and several large mountain chains.


Junior scientists topped all of this off by decorating their own pet rocks!



Red Leaf, Green Leaf: Exploring Plant Pigments

By Laura Nelson

Do you know why leaves change colors in the fall? The answer has to do with chemical compounds in leaves known as pigments. You may have heard of the green pigment chlorophyll. At the Nokomis Market on July 27, visitors explored how other pigments are present in leaves all the time but are invisible until autumn. Seasonal changes, including shorter daylight hours, cause plants to break down chlorophyll which is quite “expensive” in the amount of energy needed to produce it. Visitors explored the importance of chlorophyll in photosynthesis by recreating the photosynthetic cycle on a felt board. When photosynthesis slows in the fall and a plant breaks down chlorophyll into its components, it will recycle these component nutrients. Other pigments that were once hidden become visible because of the breakdown of chlorophyll. The pigments xanthophyll (yellows and browns), carotenoids (orange), and anthocyanins (reds and purples) are the vibrant colors we see showing through in autumn.


To explore the idea hidden pigments, market goers performed chromatography, the process of separating a substance into its components. Visitors separated colors by marking a dot on a piece of chromatography paper, dipping it in water, and observing the water soak up the paper through capillary action. The results showed that secondary colors like green separated into primary colors like blue and yellow. You can perform your own chromatography with markers at home using coffee filters.


Separating leaf pigments takes up to an hour, so market goers prepared their own take-home leaf chromatography kits. Market Scientists provided leaf samples from a common houseplant called Zebrina with bright purple and green leaves. Visitors tore the leaves into small sections, put them in a plastic vial, and covered the leaf bits with a small amount of isopropyl alcohol. Equipped with their own leaf samples, chromatography paper, and instructions, market goers left with science kits to explore leaf pigments. Curious about the results? Take a look at the chromatography paper below. Can you pick out the two primary pigments anthocyanin and chlorophyll?



Visitors separated colors with a prism, but instead of pigments, they saw different wavelengths in the visible light spectrum. Our youngest visitors also enjoyed observing leaf trichomes, or hairs, under a microscope. Thank you to Nokomis Market for welcoming the Market Scientists and for all the visitors who explored leaf colors with us!



Pollen and Plant Development

By Claire Milsted


Almost all of our food comes directly or indirectly from flowering plants (angiosperms); many plants without conspicuous flowers, such as corn, fall into this category. Angiosperms release specialized cells known as pollen to carry half of their genetic information to other plants for reproduction (though many angiosperms also pollinate themselves). This Saturday’s Market Science session at Midtown Farmer’s Market focused on pollen and plant development. Even though the farmer’s market was unexpectedly rained out before 11am, many visitors were able to participate in one or more activities designed to trace plant development from a flower to pollen to seed.

A bumblebee visits a rhododendron in Saint Paul. Bumblebees are important pollinators.

In many species, this pollen must be carried by animal pollinators. About 35% of the global food supply comes from plants that require animal pollinators. Our first activity was a guessing game that asked visitors to guess how various flowering plants are pollinated. Most visitors knew about the importance of bees, but some were surprised to learn about other important vectors of pollination. For example, corn is wind-pollinated, while the Blue Agave Cactus is pollinated by the Mexican Long-nosed Bat.

A Mexican long-nosed bat prepares to pollinate a Blue Agave Cactus. Image via nwf.org

Visitors were also offered the chance to examine various flowers both with the naked eye and with a dissection microscope. Visitors examined lilies and tomatoes, which have simple flowers with several pollen-containing anthers surrounding a pollen-receiving stigma. There were also compound flowers, with a single flower-head made of several small flowers. The compound flowers on display were chrysanthemums, the invasive species Queen Anne’s Lace, and daisies. Daisies are members of the Asteraceae family, which have flower heads that look like a single flower surrounded by petals, in fact each of the small bumps on the head are an individual disk flowers; the structures that look like petals are in fact ray flowers.

A member of the Asteraceae grows in Saint Paul

Visitors were also able to look at pollen from daylilies and tomatoes under a compound microscope. Daylily pollen was much larger and had a different shape. Finally, visitors were invited to dissect soaked beans and examine them under a dissection microscope. Volunteers explained the various components of a bean seed–its protective coat, two cotyledons which store energy for the growing plant, and a small embryo with two visible embryonic leaves (epicotyls). Hopefully these activities exploring flowers, pollinators, pollen, and seeds gave visitors a clearer view of the developmental and reproductive processes that play an important role in our gardens and on our farms.


Healthy Prairies


Have you ever seen a Minnesota prairie? If you have, you’re lucky! It is such a unique and fascinating ecosystem, but is disappearing at an alarming rate. Minnesota had over 18 million acres of prairie in the late 1800’s, and now only 1% of that remains.

A few scenes from a Minnesota prairie

The Healthy Prairies Project is a UMN research initiative funded by MN LCCMR to help conserve and restore our native prairies.  On Saturday, visitors at the Midtown Farmers Market got to meet the Healthy Prairies team and learn about this precious MN ecosystem! They even got to make their own “seed balls” filled with native perennial grass seeds, which they can take home to grow their own prairie plants.

Making seed balls filled with native MN perennial grass seeds

Perennial prairie grasses like Big Bluestem (Andropogon gerardii) and Sideoats Grama (Bouteloua curtipendula) have very deep roots that help reduce soil erosion, filter water, and store lots of carbon. Plus, they’re extremely drought tolerant!

You can compare the roots of regular turfgrass (far left) and native plants to see that natives have a lot more going on underground!

There are also a whole host of prairie wildflowers that serve as important food sources for lots of pollinators like bees and moths. You can learn more about planting a prairie garden here.

A small bumblebee seeking out nectar and pollen from Purple Coneflower (Echinacea purpurea), a MN native wildflower

But did you know there’s even cool stuff going on inside the leaves of these plants? Every leaf of every plant you see has fungi and bacteria living inside; we call these microbial dwellers leaf endophytes. At the Healthy Prairies Market Science session visitors got to see the huge diversity of fungi that live inside the leaves of some prairie plants.

These Petri dishes are growing fungi collected from leaves of Purple Prairie Clover (Dalea purpurea)

As UMN graduate student Mara DeMers explains,

If plants are filled with fungi and bacteria, just what are those microorganisms doing in there? In fact, different endophytes do different things, and there are MANY different fungi and bacteria that live as endophytes. So the short answer is: Lots of things!

What’s the long answer? Some endophytes can protect their plant hosts from being eaten, or help them survive in hot or dry places. Others might actually be pathogens, but are living as endophytes because some condition isn’t right for them to cause disease. For many endophytes, we still don’t have an answer. Maybe they help the plant, or maybe they hurt the plant, or maybe they don’t affect the plant at all. We don’t know yet!

Plant endophytes are a rapidly developing field in biology, and the Healthy Prairies team is on the forefront of research investigating the roles these microbes play in the prairie.

We hope you enjoyed visiting the Healthy Prairies team at Midtown, and that you’ve thrown your seed balls far and wide! There are lots of prairies you can visit across the state; here are a few to get you started.

Ethnobotany: Using plants for food and medicine

By Stephanie Erlandson

This Saturday (July 9) we got to strengthen our connection to plants by examining more closely what we eat, and how some common plants can be used for medicine.

We eat plants all the time, but we rarely take a closer look at what’s inside.  By dissecting plants, we can look at their seeds, their ovaries (yes, plants have ovaries!) and figure out if a specific plant part is a fruit, a leaf, a stem, or a root.  We can also learn more about how plants are related to each other.  For example, the African horned melon (kiwano) is actually closely related to the pumpkins, squash, and watermelons that are more common here in Minnesota.

There were a variety of plants available for dissection, and a map showing the origins of many different agricultural plants from around the world.  Many of the plants that we rely on for food are actually not native to Minnesota (e.g. wheat, oats, watermelon, peas, almonds, coffee).

Visitors were also asked to vote for their favorite berry, and many were shocked to learn that cucumbers are a type of berry, but raspberries and strawberries are not! After voting, visitors learned that a true berry is a fruit that is fleshy, has many seeds on the inside, and grows from only one ovary on a single flower.

Finally, we had some examples of medicinal plants (ephedra, spearmint, horsetail, ginkgo) to view, and we talked about which medicines they provide.  For example, pseudoephed came from the ephedra plant and aspirin came from willow bark.  Willow bark contains salicylic acid, which is a precursor to aspirin.  What plants did the medicines in your cabinet come from?

There are many more medicinal plants around the world that are still unknown to science, and the process of discovering them is still ongoing.  For example, a new chemical was recently extracted from the sweet wormwood plant, and it was found to be very effective at treating malaria.  The scientist to discover the drug, Tu Youyou, was awarded the Nobel Prize in 2015.

Hopefully this market science day will help encourage people to take a closer look at the plants around them, and appreciate everything that they do for us!

Genes, Genomes, and GMOs

By Diana Trujillo

On June 25, we had a session about the code underlying all living things: DNA! The purpose of the Genes, Genomes, and GMOs session was to demystify DNA and genetics for market goers.


Using commonly available items such as coffee filters, soap, salt and rubbing alcohol, kids and adults alike had great fun extracting DNA from strawberries. We learned that the “stringy white stuff”, aka DNA, contains genes, which determine strawberries’ shape, color, taste, and growth habit!

That string is an accumulation of DNA extracted from a strawberry!

In order to look at DNA more in depth, another activity was DNA origami. We put our folding skills to the test, creating a spiral staircase that depicts the double helix structure of DNA. These two anti-parallel strands contain complementary information which allows the sequence to reliably be copied and passed down from one generation to the next. Want to recreate the human genome using DNA origami? Great, only 3 billion more to go!

A very small section of DNA. We have over 3 billion base-pairs (the single letters connected to one another across the helix) in our human DNA!

For those wondering how it all comes together, we used a poster to show that DNA strands are coiled many times in order to be packaged into cells, and that the collection of all the genetic information in one cell constitutes a genome. The genes within a genome have natural variations among individuals, such as tall vs. small plants or red vs. yellow fruits. For thousands of years, humans have unknowingly selected the very best gene variants during the course of a crop’s domestication.


Newer technologies allow us to make targeted changes to genomes, such as the disruption of a gene, or introduction of new genes. The result? Genetically modified organisms, or GMOs. In one final activity, Erik showed us which produce items currently on the market are genetically modified, and explained which ones will be available in coming months.

Erik Solhaug, a University of Minnesota graduate student, shows off a mix of crops in a GMO guessing game.



Pollinators: the BUZZ about Bees

by Morgan Carr Markell

This past Saturday (June 11th) we got to teach market visitors about bees and their important relationship with flowering plants.


By gathering food from many flowers, bees provide pollination services. They carry pollen from one flower to another so that the plant can produce more plants and we humans can harvest fruit. We brought pinned bees and wasps along with close-up photos of branched bee hairs with pollen on them to show people why bees are exceptionally good at carrying pollen from one flower to another. Kids also got to make their own pollinators out of pipe cleaners (see photo below) and use them to move artificial pollen (flour) from one artificial flower (cup) to another. It was fun to see all the fuzzy, colorful pollinators that they designed!

Busy ‘pollinators’ pollinating ‘flowers’.


Some kids wanted to make pipe cleaner flowers too so Mohamed, Grace, Jason, and James worked out a method (see flower on the observation hive in the photo below). Also, we discovered that pipe cleaners and pom-poms make great antennae, which bees need to taste pollen/nectar and communicate with each other (see James’ antennae below).

James wearing his antennae.

Native Bees

We wanted to give visitors a feel for how diverse bees are. There are over 20,000 species of bees worldwide and over 400 species in Minnesota alone . They have very different lifestyles, living alone or in groups, making nests in stems or underground, and using lots of different methods for carrying pollen back to their young. They also vary tremendously in size (see photo of the pinned bees below).


We especially wanted to give people concrete steps that they can take to help bees. Lots of people asked about making artificial nests for stem-nesting bees and took our “Plants for Minnesota Bees” handout . A few even came back to show us the bee-friendly plants that they bought at the market!

Honey Bees

We had a bee veil that kids could try on, and beekeeping equipment, including a smoker and hive tool, for them to touch (see photo below). Our biggest draw was the glass-walled observation hive filled with honey bees. Everyone wanted to find the queen! She kept challenging us by moving around and hiding behind workers on the glass. Our thanks go to the nearby vendors that gave us ice for our bees. By 1 pm it was almost 100°F!


We also had goldenrod and basswood honey for people to taste and compare. Although some people loved the strong, spicy goldenrod taste, most people preferred the basswood honey’s flavor. Honey bees make honey from nectar by concentrating it down to 20% water or less and using enzymes to convert the sucrose sugar in nectar into the glucose and fructose sugars of honey. However, flowers control the specific flavor of the resulting honey by adding their own unique blend of chemicals to their nectar. Yay for biodiversity!

Atoms, Colors, and changes in our Chemical world!

by Joseph Topczewski

This past Saturday (June 4th) we were able to explore Chemistry at Market Science. Our event lived up to its name of “Atoms, Colors, and Changes in Our Chemical World!” and we explored all three in five different activities.


The first activity was centered on a color change caused by adding dry ice to water that contained a pH indicator. The dissolved CO2 (dry ice is solid CO2) formed carbonic acid and lowered the pH of the water – a reaction that we could see by color change!  This is the same process that occurs when there is an increase in atmospheric CO2, which is a leading cause of ocean acidification.


The second activity helped us see two other signs of a chemical reaction and also explained some of the ecological effects of ocean acidification. In this activity we mixed clear solutions of Na2CO3 with CaCl2 and caused the precipitation of CaCO3 as a white solid – another sign of a chemical reaction! CaCO3 is the main component of clam shells and coral and these structures are biosynthesized by a similar albeit more complex process. The CaCO3 is not always stable though. As we saw by adding citric acid, the CaCO3 dissolves in acidic solutions and then bubbles form! Bubbles are gas evolution and are a third sign of a chemical reaction. This is essentially the same reaction (sped up) that causes clams and coral to struggle to form shells in an acidified ocean.

Our third activity showed how chemistry can be handy to know about with everyday experiences. The activity focused on cleaning pennies with a little bit of science. While participants struggled to clean their penny in clean water or in soapy water, exposure to some citric acid polished it right up by dissolving the outer layer of copper oxide. See chemistry can be useful.


The fourth activity asked participants to think about what we are breathing – air. As it turns out air is a gas and gases have special properties. We explored some of those such as the relationship between volume and pressure, moles of gas, and temperature. The last was the most dramatic since we shrunk the balloons in liquid nitrogen and then let them warm up in front of us. While no extra gas was added, they got a lot bigger!


The last activity was perhaps the most popular – making SLIME! After all slime is cool. Even though the slime was a lot of fun we were also able to explain what the cross linking of polymers can do to its physical properties.


I think we had a great time at the market having fun with chemistry. I hope everyone can enjoy some chemistry this week and we hope to be back again!

Birds at the Market!

by Nick Minor, Allison Haaning, and Isabella Armour

On May 28, we had a session all about birds. We used bird specimens (from the University of Minnesota’s Bell Museum of Natural History) to examine differences within a species, differences between distantly related species with shared names (American and European robins), wing coloration, and specialized beaks. We also tried our hand at identifying local Minnesota birds by sight and call, and we made bird feeders to attract local birds. Oh–and there was live red-tailed hawk demonstration from the University of Minnesota’s Raptor Center!

Out of all the animals on earth, few reconnect us to nature quite like birds do. We explored why and learned some new things along the way.

Where to start? Before we learn anything else about birds, we have to learn their names. Naming things allows us to communicate more clearly and organize collective knowledge. Bird species are often very distinct from each other, in both appearance and sound, and their names often reflect this. For example, did you know that cardinals were named for their resemblance to Catholic Cardinals, clergy members who wore long red robes and peaked hats?  Bet you can guess how hummingbirds got their names!

Cardinals were named by Europeans in North America after the Catholic clergy members of similar appearance.

Many common Minnesota birds can also be identified by their appearances and calls. Throughout the year, even in urban areas, there are often at least ten bird species to be found. At the right place and the right time, bird species may number up to triple digits! The ability to put names on species as we observe them furthers our awareness that we share this planet with other numerous other captivating organisms. Learn your Minnesotan neighbors  from this video:


Which birds do you recognize? Which are new to you? For more information about these species, check out http://www.allaboutbirds.org.

Once you look for them, birds are everywhere! In virtually any habitat from pole to pole, we can observe a rich diversity of bird species. Wherever we look, even in highly altered urban landscapes, we can find nesting house sparrows, fluttering pigeons, yammering red winged blackbirds and so much more. All we have to do is open our eyes and ears. This ubiquity makes birds the perfect plugin to the natural world no matter where you live. How could we not wonder about them when they’re always around?

With just a little effort, we can get closer to our avian neighbors. One way to do this, of course, is with bird feeders. We hosted a simple, take-home-bird feeder making station where market-goers could construct their own feeders. For instructions to make one of the bird feeders we made, visit http://www.everydaymomideas.com/2012/10/easy-bird-feeder-craft.html.

Allison Haaning (UMn graduate student) and Isabella Armour (UMn undergraduate student) are ready to make bird snacks!

Another way to get closer to birds is with a little help from optics. Starting early in the 1900s, advances in binocular technology allowed naturalists a new way to observe species in the field – one that did not involve shooting them. Instead, naturalists could go out into the field and observe birds’ behavior as well as their plumage. Thus, a new era in nature observation was born. Along with the invention of the field guide by Roger Tory Peterson, binoculars are one of the most historically significant technologies for enhancing people’s understanding of nature. We wanted to share this with market-goers, so we brought binoculars from the Bell Museum of Natural History to demonstrate their use. Do you have a pair of binoculars at home?



Another reason why birds are so fascinating is, of course, their beauty. What could be as striking as the red of a male Northern Cardinal against the white of a snowy Minnesota winter? What could be as soothing as the song of an American Robin on a warm summer evening? Birds have aesthetically pleased us humans as long as we have coexisted with them. In birds, beauty takes on many different forms. Each of the earth’s approximately 10,000 bird species is unique, and there is even variation between individuals birds within a species. All of this variation leads to a spectacular diversity of beautiful forms, but here’s the big question: why does this exist?

We explored this diversity with some carefully selected specimens from the University of Minnesota’s own Bell Museum of Natural History. These specimens hail from around the world, each telling their own unique story and providing a treasure trove of valuable data to scientists.

Nick Minor (UMn undergraduate) displays an array of bird specimens.

We had a specimen of the diminutive European Robin to compare to the American Robin. European explorers named the American Robin after the European Robin, which shares an orange breast. But even though they are similar in appearance, 200 years later we would learn that these two “robins” are not closely related at all!

The American robin was named after the little European robin (foreground) because the they look similar.

We also had a couple specimens of the Yellow-headed Blackbird, a larger relative of the familiar Red-winged Blackbird. Both specimens were females, but one lacked dark coloration. Why? Likely some genetic mutation or illness made the white female unable to produce dark pigment. But notice that she still has yellow color. This shows that this bird produces the dark and yellow colors in fundamentally different ways: the birds produce the dark color themselves but get the yellow pigment from their diet.

These two birds are the same species, but one had a genetic mutation and can’t produce dark feathers, but it can get a yellow breast from nutrients in its food.

Some exotic, tropical specimens were also on display. We brought the extravagant Lovely Cotinga, a member of a family of birds that we might as well call South America’s birds of paradise, and the colorful Collared Aracari, a small toucan with obvious serrations on its bill for mashing up tough, tropical fruit. We also brought the metallic green Great Jacamar, which hunts large aerial insects and kills them by beating them against branches with its large bill, and a Paradise Tanager, a representative of one of the most diverse families of birds on earth.

These tropical specimens are even more brightly colored than some of our local birds!

We learned so much from our bird specimens and we explored techniques to get closer to our local birds, but we didn’t have birds stop by and check our feeders.

Katie Burns and Jamaica of the Raptor Center talk about the lives of red-tailed hawks.


Representatives from the University of Minnesota Raptor Center filled in the missing piece, arriving part-way through the morning, with Jamaica, a very-much-alive Red-tailed Hawk! Red-tailed hawks live throughout much of North America, feasting on different kinds of prey in different areas, they eat a lot of small rodents, but in some parts of the US they get more adventurous: in the American Southwest they can grab rattlesnakes! We saw an example red-tail skull that showed the large eye sockets of these birds: they use eye sight as a primary hunting tool! You may often see these hawks on roadsides, where they have open space to spy prey. We learned that roadside trash is especially dangerous for hawks: mice come and snack on the trash and then hawks can be hit by cars as they swoop in for their meal.

Jamaica is a big bird, but only weighs about three pounds! Check out those talons!

Birds are engaging to us not only because they are everywhere, or even because they are beautiful, but because they are so very wonderfully alive. Coming in so many forms, birds have the power to get us out of our own heads, every now and again, and remind us that there are exciting, mysterious, and surprising things happening around us all the time.

And all we need to do, then, is take a step back and look.

Many thanks to all those who joined us on May 28th! Special thanks to the Minnesota Raptor Center and the Bell Museum of Natural History!

P.S. Here are some handy bird-related resources for diving deeper into birding:

http://ebird.org/ – Come here to explore local citizen science data to find species and contribute your own observations to science.

http://feederwatch.org/ – Do you have a birdfeeder? Using this citizen science project, your observations could contribute to science.

https://www.allaboutbirds.org/ – One of the best online bird guides.

http://www.audubon.org/bird-guide – The National Audubon Society’s online bird guide, which recently got a beautiful design overhaul.

https://moumn.org/ – The website of the Minnesota Ornithologists’ Union, one of the pre-eminent bird groups in Minnesota.

http://mn.audubon.org/ – Minnesota Audubon coordinates birding trips, conservation outings, and everything in between for Minnesota birders.