Archives For Plant Science & Conservation

Conserving plants is one of the most significant challenges of our time—and a major focus at the Chicago Botanic Garden. From studying soil to banking seeds, from restoring habitats and protecting endangered plant species to developing new ones, Garden scientists are fighting plant extinction, pollution, and climate change through diverse and exciting research.

Just below the summit, we scrambled past enormous boulders to an unhappy sight—a small group of beautiful aspens in big trouble.

As curator of woody plants at the Chicago Botanic Garden, I’m interested in what’s happening to quaking aspen (Populus tremuloides) because the trees have become increasingly threatened by geologic disturbance and climate change. The Garden is part of a research group that’s working to collect root pieces and other genetic material from the aspens in the Chisos Mountains of west Texas; the material will allow us to raise the trees in cultivation and then plant new ones in the wild. The quaking aspens project is just one part of a broader Garden goal to protect species and promote biodiversity.

As part of the initiative, I met with Adam Black, director of horticulture at the famed Peckerwood Garden in Hempstead, Texas. Adam is a plant geek at heart and knows the Chisos Mountains intimately from 20-plus years of exploring there. He put together the collaboration between the Chicago Botanic Garden, Peckerwood Garden, the National Park Service, and the University of Florida School of Forest Resources and Conservation.

Quaking aspen growing out of the boulder field below Emory Peak, Big Bend National Park (white trunks visible in foreground)

Quaking aspen growing out of the boulder field below Emory Peak, Big Bend National Park (white trunks visible in foreground)

In mid-February, Adam and I began the long, steep trek toward Emory Peak, in Big Bend National Park, gaining about 1,800 feet of elevation in 4 miles. Passing through Laguna Meadows, I first glimpsed the stunning white bark of the aspens growing out of enormous boulders above us. Adam and I dropped our packs and scrambled across the boulder field, photographing the terrain and aspens as went.

The chalk-white bark of these quaking aspens (Populus tremuloides) contrasts with the Mexican pinon pine (Pinus cembroides) growing amongst the boulder field.

The chalk-white bark of these quaking aspens (Populus tremuloides) contrasts with the Mexican pinyon pines (Pinus cembroides) growing in the boulder field.

When we reached the trees, it quickly became clear that this grove of aspens was unlike any other I had seen before. Aspens usually grow in enormous clonal groves, which means that the trees are essentially a single plant, connected by one elaborate root system. The grove below Emory Peak includes only 40 trees or so, in poor health. Jason Smith, Ph.D., forest pathologist at the University of Florida in Gainesville, believes that the trees are under stress from the radiant heat of the rocks in which they are growing. When the trees grow to about 25 feet high, they get a canker disease—a fungal infection—and quickly die. 

Adam and I collected root pieces and shoots from six separate trees in the grove, all good genetic material that will allow us to cultivate the plants. Reaching the roots was no easy task. The aspens are growing in the remains of what appears to be a major rock collapse from an igneous intrusion, or rock formed from intense heat that has crystalized into molten magna. While most aspen colonies spread upward from roots in less than 18 inches of soil, these trees grow through several feet of stacked boulders. As we moved from tree to tree, I struggled to keep my footing on the shaky boulders and tried not to cause a rock slide down the mountain.

With GPS data and root sections in hand, Adam and I climbed up to the mountain’s East Rim, where we were rewarded with stunning views of the Chisos Mountains, canyons carved out by the Rio Grande River and Maderas Del Carmen Reserve in northern Mexico. The next morning, camping on the mountain rim, watching the sunrise cascading across the United States-Mexico border, I forgot about the 8-mile descent ahead of me until it was time to pack up and go. During the hike down, Adam and I stopped by the second group of quaking aspens that we’re studying; a month earlier, Adam and Dr. Smith had collected root pieces from the trees for propagation.

Sunlight fading over Sierra Del Carmen in Coahuila, Mexico

Sunlight fading over Sierra Del Carmen in Coahuila, Mexico

After the team cultivates new plants from the genetic material we collected, the trees will be distributed to botanic gardens and arboreta across the country and added to the institutions’ conservation collections. The team is also doing genetic testing on the Chisos Mountains trees to determine how they relate to other aspen populations.


©2018 Chicago Botanic Garden and

The SciFi Rant

Boyce Tankersley —  March 2, 2018 — 6 Comments

I have been a fan of science fiction since the early days of Star Trek on TV (Yep, I am that old). I think it is one of my strengths, as a scientist, that I have the ability to visualize “out of bounds” solutions. I like to think this open-mindedness has contributed to my successes.

I discovered a love of growing plants and archaeology as a young child on a ranch in West Texas, surrounded by miles of vegetation and peppered with intriguing traces of the people that had lived on the land before I got there.

Coming from a family of modest means, I realized that I did not have the luxury of “discovering myself” at college, and so at 16, I made a short list of possible careers with their pros and cons: growing plants and studying ancient civilizations. Neither career path was going to result in wealth, but that was not a major goal in my life’s plan. (Yes, I have on several occasions wished for time travel to reevaluate the advantages of wealth.) A strong contender was archaeology, but one of the cons was that if I were out of a job, I would not have the skills to grow food to feed my family. Don’t you just love spreadsheets? So growing plants was to be my career—and if I were unemployed, at least I would have the skills needed to grow food for my family.

I soon learned that within the whole plant science field were a number of specializations, not just “growing things”: horticulture, botany, plant taxonomy, plant physiology, plant genetics, agronomy, and plant pathology. Yikes, another decision!  Like any good budding scientist, I knew research was in order:

  • Horticulture is the art and science of growing plants.
  • Botany is the scientific study of plants, including their physiology, structure, genetics, ecology, distribution, classification, and economic importance.
  • Plant Taxonomy is the science that finds, identifies, describes, classifies, and names plants.
  • Plant Physiology is a sub-discipline of botany concerned with the functioning—or physiology—of plants.
  • Plant Genetics deals with heredity in plants, specifically mechanisms of hereditary transmission and variation of inherited characteristics.
  • Agronomy is a branch of agriculture dealing with field-crop production and soil management.
  • Plant Pathology is defined as the study of the organisms and environmental conditions that cause disease in plants, the mechanisms by which this occurs, the interactions between these causal agents and the plant (effects on plant growth, yield and quality), and the methods of managing or controlling plant disease.

Horticulture was the name of the discipline I wanted to specialize in, and that, as radio commentator Paul Harvey used to say, “was the rest of the story.”

So where does the rant about SciFi fit in?

Siting on the couch with my son and watching E.T. the Extra-terrestrial for the umpteenth time, I was dismayed to learn in the director’s cut that the original title had been The Botanist. Now everyone in plant sciences knows that botanists are great folks to share a beer with, but they are lousy at growing plants. If they could grow plants ,they would be horticulturists, not botanists. But I let this one slide, Steven Spielberg is a great guy, and everyone deserves a break sometimes. Besides, in an alien culture, perhaps the two are more closely aligned. (Another example of out-of-the-box thinking!) 

Fast forward to The Martian, a real thriller that pushed all of the right buttons in my SciFi loving psyche…except that they described the survivor as a botanist. No self-respecting botanist would know enough about growing plants and their requirements to pull off that feat. Nope, another missed opportunity. Obviously a horticulturist; a botanist would have studied the tubers as they dried up and died. The horticulture field just lost another opportunity to attract the first generation to grow plants on another planet!

ET: A tiny botanist, or maybe something a little more cross-disciplinary? Photograph: Allstar/Cinetext/Universal

ET: A tiny botanist, or maybe something a little more cross-disciplinary? Photograph: Allstar/Cinetext/Universal

Mark Watney may be a biologist, but here he's a horticulturist. Photo via

Mark Watney may be a botanist, but here he’s a horticulturist. Photo via

The stomach flu earlier this year was a really unpleasant experience, but while channel surfing Netflix last weekend, I came across a SciFi series called The Expanse. Yep, that was me for four days straight—watching a total of 26 episodes—knowing that I was out of it enough to be able to come back in a time of health and catch some details my fevered brain didn’t absorb. (Yes, Netflix was concerned and periodically offered me alternatives, but I was hooked.)

About halfway through the second season, the action shifts to a food production facility featuring solar collectors, greenhouses, and plants grown in hydroponic solution. Vital to survival of our species in space, plants cleanse the air and provide nutrition for space-based operations—NASA has been working on it for at least 40 years. Great scenes, great actor, actually got the technical terminology right…and then they referred to him as a botanist!

My wife, son, and our new puppy came rushing to my bedside—such a cry of anguish they had never heard. They reassured neighbors at the door that everything really was “all right.” Ugh!

A FluorPen is used to measure the chlorophyll fluorescence of Arabidopsis thaliana plants.

John “JC” Carver, a payload integration engineer with NASA Kennedy Space Center’s Test and Operations Support Contract, uses a FluorPen to measure the chlorophyll fluorescence of Arabidopsis thaliana plants inside the growth chamber of the Advanced Plant Habitat (APH) Flight Unit No. 1. Half the plants were then harvested.

Dear SciFi movie writers, directors, etc.: In space, plant scientists probably wear many hats, but please note: horticulturists grow plants; botanists study them.

©2018 Chicago Botanic Garden and

In honor of Black History Month, I would like to call attention to a botanist who would have fit in very well at the Chicago Botanic Garden: George Washington Carver. He was a gardener, a soil scientist, an inventor, a genius, and a good guy.

George Washington Carver (1864–1943)

George Washington Carver (1864–1943)

You probably know Carver as the famous black scientist who invented dozens of products for peanuts. What’s most important about his story is why he devoted so much time and ingenuity to peanuts and how he did so much more than make a high protein sandwich spread and cooking oil.

I’m not a historian or biographer, so this story will omit details about Carver’s life—being born into slavery,  studying agriculture in an era of racial discrimination, and becoming a botany professor at Tuskegee University. While these details are interesting and definitely worth learning, you can read about all that in other places. Instead, this snapshot is devoted to celebrating how one humble scientist used his botanical superpowers to solve a real-world problem. It is a story about successfully tackling agricultural sustainability and economic stability at the same time.

Carver grew up in the south and he knew the agricultural conditions very well. Soil in the southern states is fine and dry. Summers are long and hot. These are suitable conditions for growing cotton, a profitable cash crop. The problem is that cotton needs a lot of nitrogen. Several years of growing cotton on the same patch depletes the soil, making the crop yield less and less over time. In the late nineteenth century, commercial fertilizer was not available—and even if it had been, the poor people who worked the land couldn’t have afforded it. To make things worse, in 1892 a little pest called the boll weevil moved northward from Mexico and began invading and destroying cotton crops. The boll weevil population spread and plagued the south through the 1920s and ’30s, making the life of a cotton farmer even harder and less rewarding.

Peanut plant (Arachis hypogaea)

Peanut plant (Arachis hypogaea)
Photo by Biswarup Ganguly [GFDL or CC BY 3.0], via Wikimedia Commons

A cotton boll weevil (Anthonomus grandis)

A cotton boll weevil (Anthonomus grandis)

Freshly harvested peanuts, still attached to the roots of the plant.

Freshly harvested peanuts
Photo by Pollinator [GFDL or CC-BY-SA-3.0], via Wikimedia Commons

Carver knew this life because he had lived it, and he wanted to make it better. He worked to teach farmers about crop rotation. Legumes (like peanuts and soybeans) and sweet potatoes have the ability to convert nitrogen from the air to a form that plants can absorb from the soil. Planting what is called a “cover crop” of peanuts instead of cotton for a year restores the nitrogen in the soil so the cotton grows better the next year. As an added benefit, diversifying crops by growing peanuts and other plants that the weevils do not eat helps reduce their population so there are fewer to harm the cotton crops. Sounds like the answer to all of their problems, right? So of course, farmers changed their practices right away, and lived happily and sustainably ever after.

Not quite.

You see, at that time peanuts were only used as cheap feed for livestock, and nobody was buying a lot of them. A farmer could not earn as much money growing peanuts as he could from his dwindling crop of cotton, so changing crops was financially risky, even as the cotton was failing. Carver realized he had to solve the market problem or farmers were never going to plant cover crops. THAT is why he set out to invent more than 100 uses for peanuts from 1915 to 1923. 

Products that were developed by George Washington Carver and made available commercially.

Products that were developed by George Washington Carver and made available commercially. Photo via the National Park Service Legends of Tuskegee exhibition.

He didn’t stop there, He also worked to promote his inventions to businessmen and investors in order to create a demand for peanuts, because, as we all learned in high school economics, when the demand goes up so does the price. Then—and only then—did the sustainable practice of crop rotation take hold.

But wait, there’s more.

The increased demand for peanut products also led to an increase in peanuts imported from other countries. In 1921, Carver spoke to Congress to advocate for a tariff on foreign peanuts so American farmers would be protected from the competition. Though it was highly unusual for a black man to speak to Congress in those days, his appeal won over the legislators and tariffs were imposed.

Peanut flower (Arachis species)

Peanut flower (Arachis sp.)

George Washington Carver did not seek wealth or fame for his work. He found personal satisfaction in scientific discovery and using his talents to make the world a better place for farmers and everyone. I believe if he were alive today, he would have embraced the challenge of researching and teaching people about sustainable urban agriculture to improve the health, nutrition, and livelihood of low-income city dwellers just as he did for rural farmers 100 years ago, and I believe programs like our Windy City Harvest grow out of that same spirit and desire to help people make a better living for themselves.

©2018 Chicago Botanic Garden and

Pop quiz: What kind of natural habitat is increasing in urban areas? This is not a trick question. Rather, the answer offers a slice of good news on a planet that has been increasingly turning from green to gray.

Green roofs are on the rise in cities, according to Kelly Ksiazek-Mikenas, Ph.D., who has a newly minted doctorate degree from the Chicago Botanic Garden and Northwestern University’s graduate program in plant biology and conservation. In Illinois, where more than 99 percent of native prairie has been lost since the 1800s, this is especially good news. 

Kelly Ksiazek-Mikenas in the Plant Science Lab

Kelly Ksiazek-Mikenas, Ph.D., in the Plant Science Lab

Dr. Ksiazek-Mikenas, a former biology teacher, spent six years studying these engineered habitats and their potential to support biodiversity.

The plant scientist is now eager to share her findings: When started carefully and with a long-term plan in mind, these sites do grow up to support species, natural communities, and genetic diversity.

“When you have these three pieces working, you have a good foundation that should sustain plant life over long periods of time and live through environmental changes, and that look and function like a diverse prairie,” she said.

Dr. Ksiazek-Mikenas examined shallow (up to six inches of soil depth), low-moisture roofs from Glencoe, Illinois, to Neubrandenburg, Germany, before reaching that conclusion. While the roofs within the United States are generally younger, some in her German sites were up to 93 years old, providing a mix of data about green roofs at all ages. She also studied data sets and conducted shorter-term experiments to clarify the qualities green roofs need to succeed.

Setting up insect traps in 2013 on a green roof on top of the Berliner Wasserbetriebe building in downtown Berlin

Dr. Ksiazek-Mikenas sets up insect traps in 2013 on a green roof in downtown Berlin.

Her work had its ups and downs. She arrived in Germany looking for similarities, expecting the insect and plant species on one roof to mirror that on the others. Rather, she found differences between roof gardens. After a deep dive into data, she found the secret. Although the plant species differed between gardens, those that grew well shared the traits of being stress-tolerant and adept at establishing themselves in new areas.

She was concerned by the lack of diversity on individual roof gardens both in Germany and in her study sites in Chicago.

Back at the Chicago Botanic Garden, she set up an experiment to test how different soil types would affect which plants were successful, and whether she could create a more diverse community on one rooftop by planting both rock and sand prairies.

She planted her experimental plots on the Josephine P. & John J. Louis Foundation Green Roof Garden North on the Daniel F. and Ada L. Rice Plant Conservation Science Center and monitored activity over three years. She found success in growing a more diverse habitat. In related work at the same site, she confirmed that native plantings, rather than the common sedum plant mix used on roof tops, offered benefits similar to a native prairie when it comes to storing rainwater, for example.

The Plant Science Center’s Green Roof Garden is an important resource. Planted in 2009, it serves as a living laboratory, classroom, research site, and a source of inspiration to visitors.

The north side of the green roof of the Chicago Botanic Garden Plant Science Center in 2015, including a blooming population Penstemon hirsutus used in one of Dr. Ksiazek-Mikenas' experiments

A blooming population of Penstemon hirsutus was part of  Dr. Ksiazek-Mikenas’ experiments.

She then expanded to include plots on the Ellis Goodman Family Foundation Green Roof Garden South to study genetic diversity. She compared the genetic diversity of populations established from nursery stock to natural populations, finding more diversity in the natural populations grown from wild collected seed.

On the heels of that finding, she studied populations on green roofs in Chicago near Lake Michigan to find out if the plants were able to share their genetic material with plants on neighboring roofs through pollination. She was thrilled to confirm that they did, as the exchange of diverse genetic material is essential for the long-term health of a species.

Although there are limitations to green roof gardens, mainly due to the lack of soil depth and disconnected setting, Dr. Ksiazek-Mikenas is optimistic about their ability to sustain native species. She has presented her work at numerous conferences across the globe to academics and those in the landscaping industry.

Two prairie species in Dr. Ksiazek-Mikenas' experimental plots blooming on a green roof on the Peggy Notebaert Nature Museum in Chicago

Two prairie species in Dr. Ksiazek-Mikenas’ experimental plots—Ratibida pinnata (foreground, right) and Lespedeza capitata (background, left)—bloom on a green roof on the Peggy Notebaert Nature Museum in Chicago.

“In the future, I hope that green roofs can continue to provide ecosystem services to people but also increasingly support a wide variety of urban biodiversity,” she said.

The motivated researcher is ready to move ahead with her career and intends to continue to bring her unique perspective to future students and to the development of more green infrastructure in this growing world.

©2018 Chicago Botanic Garden and

Why did five Midwestern horticulturists hike through the oak-hickory forests of the Missouri Ozarks? And why did we need a desiderata? The first question is easy—we were on the trail of specific wildflowers and woody plants to preserve and add to our collections.

Collections trip horticulturists Mike Jesiolowski, Tom Weaver, Josh Schultes, Kelly Norris, and Steve McNamara

Collections trip horticulturists Michael Jesiolowski, Tom Weaver, Josh Schultes, Kelly Norris, and Steve McNamara (left to right)

In a trip funded by the Plant Collecting Collaborative (PCC), a consortium of public gardens, Tom Weaver (horticulturist, Dwarf Conifer Garden) and I (senior horticulturist, Entrance Gardens) joined Kelly Norris (the trip leader) and Josh Schultes of the Greater Des Moines Botanical Garden, along with Steve McNamara of the Minnesota Landscape Arboretum. Before we left, our desiderata—or essential list of desirable plants we would target—was developed, based on what plants our gardens deemed important for conservation, to fill a gap in our collections, or add beauty to our display gardens. And of course, we had the proper state and federal permits in hand for seed collecting. The six areas that we explored were typically oak-hickory forests, which opened up to rocky-soiled glades and provided for plentiful opportunity for collecting wildflowers. With an eye for distinct plant material and genetic diversity, we roamed through the uneven Ozarks terrain, but we weren’t tied to our wish list—we also found a couple of surprises.

Glade opening at Roaring River State Park

Glade opening at Roaring River State Park

Since seed-grown plants are reproduced sexually through pollination, via wind or insects/animals, they are genetically variable. A variety of genes can give each plant the best chance to exhibit a specific phenotype, or physical appearance, and better adaptability to survive pests and diseases. Where seeds are collected could have significant implications on whether a plant can survive in a given environment or not. For instance, we collected seeds of Echinacea paradoxa (yellow coneflower) from its northern most growing region, in Ha Ha Tonka State Park in Missouri. Selecting seeds of Missouri provenance gives this wildflower a better chance of survival in our region, rather than if the seeds had been collected in Texas. Plants that have a different phenotype from what we commonly observe in northern Illinois were of special interest to us. Fruit from Diospyros virginiana (common persimmon) was collected on a 4-foot-tall tree in Mark Twain National Forest because it is unusual to see fruit on a tree of such short stature. In a similar fashion, Symphoricarpos orbiculatus (coralberry), was collected from the Big Buffalo Creek Conservation Area, after we all remarked at the stunning ornamental quality of the fruit display.  

Yellow coneflower (Echinacea paradoxa)

Yellow coneflower (Echinacea paradoxa)

Persimmon (Diospyros virginiana)

Persimmon (Diospyros virginiana)

Josh Schultes examines some holly (Ilex decidua) for collection.

Josh Schultes examines possumhaw holly for collection.

In some cases, we came across desirable plants, but they had already dropped their seed for the year, or simply didn’t produce any due to drought-induced stress. With the aid of GPS, we marked these areas so future explorers to the Ozarks are aware of these plants for their potential collections. For example, Boyce Tankersley, the Chicago Botanic Garden’s director of living plant documentation, was a part of a team that collected in many of these same areas in 2005; their field data was helpful in our search.

Dotted blazingstar (Liatris punctata)

Dotted blazingstar (Liatris punctata)

Although the Ozarks region experienced a late-summer drought that negatively impacted seed production in some instances, we were still able to make 71 collections from October 12 to 16. Our seeds will be grown in our plant production greenhouses. Once they achieve a certain size, they will be distributed to PCC members and planted in the Garden. I am ecstatic to cross Liatris punctata (dotted blazingstar) off the desiderata for use in my gravel garden project in parking lot 1. The seeds we collected should be ready to plant in these beds in two years.

©2017 Chicago Botanic Garden and