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.
Students in the Chicago Botanic Garden and Northwestern University Program in Plant Biology and Conservation were given a challenge: Write a short, clear explanation of a scientific concept that can be easily understood by non-scientists. Each week this spring, we’ll publish some of the results.
These brief explanations cover the topics of seed dormancy and germination, the role of fire in maintaining prairies, the evolution of roots, the Janzen-Connell model of tropical forest diversity, and more. Join us the next several weeks to see how our students met this challenge, and learn a bit of plant science too.
Alexandra Seglias is a second-year master’s student in the Plant Biology and Conservation program at Northwestern University/The Chicago Botanic Garden. Her research focuses on the relationship between climate and dormancy and germination of Colorado Plateau native forb species. She hopes that the results of her research will help inform seed sourcing decisions in restoration projects.
The seed is an essential life stage of a plant. Without seeds, flowers and trees would not exist. However, a seed doesn’t always live a nice, cozy life in the soil, and go on to produce a mature, healthy plant. Similar to Goldilocks, the conditions for growth of a seed should be “just right.” The charismatic acorn is just one type of seed, but it can be used here as an example. Mature acorns fall from the branches of a majestic oak and land on the ground below the mother tree. A thrifty squirrel may harvest one of these acorns and stash it away for safekeeping to eat as a snack at a later time. The squirrel, scatterbrained as he is, forgets many of his secret hiding places for his nuts, and the acorn has a chance at life. But it’s not quite smooth sailing from here for that little acorn.
Imagine trying to be your most productive in extreme drought, or during a blizzard. It would be impossible! Just as we have trouble in such inhospitable conditions, a seed also finds difficulty in remaining active, and as a result, it essentially goes into hibernation until conditions for growth are more suitable. Think of a bear going into hibernation as a way to explore seed dormancy. The acorn cozies up in the soil similar to the way a bear crawls into her den in the snowy winter and goes to sleep until spring comes along. As the snow melts, the bear stretches out her sore limbs and makes her way out into the bright world. The acorn feels just as good when that warmer weather comes about, and it too stretches. But rather than limbs, it stretches its fragile root out into the soil and begins the process of germination. This process allows the seed to develop into a tiny seedling — and perhaps eventually grow into a beautiful, magnificent oak tree.
On October 25 last year, I met Matt Lobdell, curator at the Morton Arboretum, in Orange Beach, Alabama, to begin a ten-day plant expedition trip to Alabama, Georgia, and South Carolina.
Matt Lobdell had received a grant from the American Public Gardens Association and the U.S. Forest Service in the spring to collect seed of Quercus oglethorpensis from as many genetic populations as possible, so that the breadth of this species could be preserved in ex-situ collections in botanic gardens and arboreta. This expedition was an opportunity to collect this species and other important oak species, as well as other species of trees, shrubs, and perennials that could be added to our collections.
We were targeting the collection of four oaks with conservation status: Oglethorpe oak (Quercus oglethorpensis), Georgia oak (Quercus georgiana), Boynton sand post oak (Quercus boyntonii), and Arkansas oak (Quercus arkansana). All four of these oaks are on the International Union for Conservation of Nature (IUCN) Red List, which identifies plants that have important conservation status. (Quercus georgiana and Q.oglethorpensis are listed as endangered.)
Matt Lobdell at the Morton Arboretum and Greg Paige at Bartlett Tree Research Laboratory and Arboretum make an herbarium voucher of Quercus boyntonii.
Any successful plant expedition is the result of a very collaborative effort. Because we are often looking for hard-to-find species, we rely on local experts. For different parts of the trip we had guidance from Mike Gibson of Huntsville Botanical Garden; John Jensen and Tom Patrick at the Georgia Department of Natural Resources; Brian Keener at the University of Western Alabama, assisted by Wayne K. Webb at Superior Trees; Fred Spicer, CEO of Birmingham Botanical Gardens; and Patrick Thompson of Davis Arboretum at Auburn University.
We were also joined by other institutions that helped with both the collection of seed and the associated data, but also helped with the collecting of two herbarium vouchers for each collection (pressed specimens), which are now housed in the herbaria at the Morton Arboretum and Chicago Botanic Garden respectively. Assistance was provided by Tim Boland of Polly Hill Arboretum; Amy Highland and Cat Meholic of Mt. Cuba Center; Ethan Kauffman of Moore Farms Botanical Garden; and Greg Paige from Bartlett Tree Research Laboratory and Arboretum.
Our expedition begins
On October 26, we collected at Gulf State Park in pelting rain and very high winds that resulted from the remnants of Hurricane Patricia, which had made landfall near Puerto Vallarta days earlier. Nevertheless, we found several small, windswept oaks in this sandy habitat, including Q. myrtifolia, Q. minima, Q. geminata, and Q. chapmanii.
Talladega National Forest
The next day, we moved north to the Talladega National Forest in central Alabama. In addition to collecting more oaks, we made collections of the beautyberry (Callicarpa americana), Euonymus americanus, and the buttonbush (Cephalanthus occidentalis). We also saw fantastic specimens of the big-leaf magnolia (Magnolia macrophylla), but we were too late to find any viable seed.
Quercus boyntonii
Fred Spicer, CEO of the Birmingham Botanical Gardens, joined us the next day, October 28, to take us to several populations of Q. boyntonii, where we were able to make collections for six different populations. He also took us to Moss Rock Preserve in Jefferson County, where we made collections of the Georgia oak (Quercus georgiana). We also made a collection of the Carolina silverbell (Halesiatetraptera).
On October 30, we spent the day in Sumter County, Alabama, with Brian Keener, where we encountered Quercus arkansana, Dalea purpurea, Viburnum rufidulum, and Liatris aspera.
On October 31, we botanized in Blount County, Alabama, at Swann Bridge. Below the bridge was a small river, where we saw an array of interesting plants including the yellowroot (Xanthorhiza simplicissima); hornbeam (Carpinus caroliniana); a small St. Johnswort (Hypericum prolificum); and a native stewartia (Stewartia malacodendron), in which we were able to find a few seeds. From there we continued on to the Bibb County Glades and collected Silphium glutinosum and Hypericum densiflorum.
Bibb County GladesMoss Rock Preserve at the habitat of Quercus georgiana
On the following day, we made another collection of Quercus boyntonii in St. Clair Country and then headed to the Little River Canyon in Cherokee County. This was a rich area filled with native vegetation of many popular plants including the maple leaf viburnum (Viburnum acerifolium), with its wine-red fall color; both the smooth hydrangea (Hydrangea arborescens), and the oakleaf hydrangea (Hydrangea quercifolia); the winterberry holly (Ilex verticillata), and the Carolina allspice (Calycanthus floridus). Interestingly, many of these Alabama natives are perfectly hardy in the Chicago area.
Toward the end of the trip, we headed into Jasper County, Georgia, and met up with John Jensen and Tom Patrick of the Georgia Department of Natural Resources, who helped us find populations of Quercusoglethorpensis. In Taylor County, we collected several oaks, including Q. margarettae, Q. incana, and Q.laevis.
We finished the expedition in Sumter National Forest in McCormick County, South Carolina. This was the final collecting site for Q. oglethorpensis, which was cohabiting with Baptisia bracteata and Q.durandii.
Little River CanyonQuercus oglethorpensis seedlings in Jasper Country, Georgia
An expedition’s rewards
In total, we made 92 collections of seed and herbarium vouchers. The seed is being grown at both the Chicago Botanic Garden and the Morton Arboretum. Most likely, plants will not be ready for distribution until 2017 and most likely would not be planted into the Garden’s collections until 2018 at the earliest.
In spring 2016, Northwestern University graduate student Jordan Wood will retrace some of our steps in search of leaf samples of Q. oglethorpensis so he can study the DNA and fully understand the genetic breadth of this species throughout its native range from Louisiana to South Carolina.
In a first-time summer internship research project, two college students set out to understand how plants were responding to the Garden’s shoreline restoration projects. They took a deep look into how variations in water levels may be affecting the health of the young plants. The results of their work will help others select the best plants for their own shorelines.
A silent troop of more than one-half million native plants stand watch alongside 4½ miles of restored Chicago Botanic Garden lakeshore. The tightly knit group of 242 taxa inhibit erosion along the shoreline, provide habitat for aquatic plants and animals, and create a tranquil aesthetic for 60 acres of lakes.
Now ranging from 2 to 15 years old, the plants grow up from tiered shelves on the sloping shores. Species lowest on the slope are always standing in water. At the top of the slope, the opposite is true, with only floods or intense downpours bringing the lake level up to their elevation.
Wading In
Jannice Newson and Ben Girgenti moved through clusters of tightly knit foliage along the Garden shoreline from June through August, taking turns as map reader or measurement taker. On a tranquil summer day, one would step gingerly into the water, settling on a planting shelf, before lowering a 2-foot ruler into the water to take a depth measurement. The other, feet on dry land, would hold fast to an architectural map of the shoreline while calling out directions or making notes.
Newson, a Research Experiences for Undergraduates (REU) intern and sophomore at the University of Missouri, and Girgenti, a Garden intern and senior at Brown University, worked under the guidance of Bob Kirschner, the Garden’s director of restoration ecology and Woman’s Board curator of aquatics.
Interns Ben Girgenti and Jannice Newson gather plant data on the shoreline.
When the summer began, Girgenti and Newson had hoped to locate and measure every single plant. But after the immense scope of the project became clear in their first weeks, they decided to focus on species that are most commonly used in shoreline rehabilitation, as that information would be most useful for others.
“We’re interested in which plants do really badly and which do really well when they are experiencing different levels of flooding, with the overall idea of informing people who are designing detention basins,” explained Girgenti, who went on to say that data analysis of the Garden’s sophisticated shoreline development would be especially useful for others.
“The final utility of this research will be to inform other natural resource managers,” confirmed Kirschner, who added that successful Garden shoreline plants must be able to withstand water levels that can rise and fall by as many as 5 feet several times in one year.
Steering the Ship
Along the shoreline, the interns followed vertical iron posts that were installed as field markers during construction, in order to find specific plants shown on the maps. “The posts are pretty key to being able to map out the beds,” said Girgenti.
The Malott Japanese Garden shoreline two years after the 2006 restoration project.
Once they found a target plant, they then counted clumps of it, and put it into one of six categories based on the amount of current coverage, ranging from nonexistent to area coverage of more than 95 percent.
They also measured the average depth of water for beds with plants below the water line, noting their elevation. For plants above the water line, the elevation was derived from the architectural drawings.
Data about the elevation and coverage level of each measured plant, together with daily lake water level readings dating back to the late 1990s, was then entered into a spreadsheet and prepared for analysis to identify correlations between planting bed elevation and plant survival.
Beneath the Surface
For her REU research project, Newson was careful to collect data for one species in particular, blue flag iris. “As a preliminary test of the project hypothesis, data relating to 101 planting beds of Iris virginica var. shrevei were analyzed to see if there was a significant correlation between the assessed plant condition and each planting bed’s elevation relative to normal water,” she explained in her final REU poster presentation in late August.
Southern blue flag iris (Iris virginica var. shrevei), photo by Jannice Newson
An environmental science major, she initially experienced science at the Garden as a participant in the Science First Program, and then as a Science First assistant, before becoming an REU intern.
Girgenti began his Garden work in the soil lab, where his mentor inspired him to focus on local, native flora. “I was kind of pushed up a little bit by the Garden,” he said. The following year he did more field work in the Aquatics department. “I wanted to come back because I really enjoyed being here the last two years,” he said. “Every year I’ve come back to the Garden, I’ve been very excited about what I’m going to do.”
Aside from the scientific discovery, the two also refined their professional interests. “I do enjoy being out in the field as opposed to maybe working in a lab; it’s a lot more interesting to me. And also just working in the water with native plants is very interesting,” said Newson.
“I was really interested in getting into more of the shoreline science and also learning which native species were planted there,” said Girgenti. “I really love working here. I’ve never really been involved this much in science, so this has been a really great experience—just all of the problem solving that we’ve had to do over the course of the summer.”
Newson also enjoyed the communication aspect of her work, as Garden visitors stopped to ask what work she and Girgenti were doing along the shoreline. She was especially excited to share with them and her fellow REU interns that “the purpose of why we are doing this is that it provides a beautiful site for visitors to see, it helps with erosion, and also improves aquatic habitat.”
A view of the Kleinman Family Cove highlights the small bay where our youngest science explorers can learn about the shoreline.
Although the interns have left the Garden for now, the data they collected will have a lasting impact here and potentially elsewhere. Kirschner is currently working with his colleagues on the data analysis to complete a comprehensive set of recommendations for future use.
When you lift a rock in your garden and glimpse earthworms and tiny insects hustling for cover, you’ve just encountered the celebrities of soil. We all know them on sight. The leggy, the skinny, the pale…the surprisingly fast.
Behind this fleeting moment are what may be considered the producers, editors, and set designers of the mysterious and complex world of soil—fungi. They often go unrecognized, simply because most of us can’t see them.
Otidea, a decomposer
Fortunately, new technologies are helping experts, like Chicago Botanic Garden scientist Louise Egerton-Warburton, Ph.D., get a better look at fungi than ever before, and discover vital information.
“One of the problems we have with soil science is that you can’t see into it so you really depend on a lot of techniques and methods to work out what’s happening,” explained Dr. Egerton-Warburton, associate conservation scientist in soil and microbial ecology.
In the last year, she has used high-throughput sequencing (also termed Next Generation Sequencing) to identify more than 120 species of mycorrhizal fungi in a single plant community. In contrast, previous reports suggested there were, at most, about 55 mycorrhizal species in a plant community. These tiny heroes are microscopic organisms that attach themselves to plant roots, for example, to carry out critical functions that support all life on earth. They are essential for the well-being of more than 85 percent of all plants, including those in your garden.
Mycorrhizal fungi are fungi that have a symbiotic relationship with roots of a vascular plant; from the Greek for “fungus” and “root.”
Mushrooms are the above-ground fruiting body of fungi.
If climate change results in more intense rainfall and drought—as is predicted by climate change scientists—mycorrhizal fungi will also play an important role in processing varied levels of water in the soil.
Egerton-Warburton has just returned from November field work in the Yucatán peninsula of Mexico, where she has been testing the responses of mycorrhizal fungi to changes in rainfall and soil moisture, especially to drought. Will fungi be able to keep pace? Will they be able to survive? What does that mean for other plant life? “Fungi are really good indicators of any environmental problems. So they are more likely to show the effects of any environmental stress before the plants will,” she said.
Each type of fungi also has a specific role, according to Egerton-Warburton, with some specialized to take up nutrients from the soil, while others cooperate to complete a function, such as fully decomposing a leaf. A lot of fungi are needed to keep the system working. “You get 110 yards of fungal material in every teaspoon of soil,” she explained.
Aside from breaking down deceased plant material, fungi play a key role in many plant-soil interactions and the redistribution of resources in an ecosystem. They filter water that runs into the ground, cleaning it before it hits the bottom aquifers and drains out into rivers. Also, in the top few inches of soil, many fungi are respiring, along with their earthworm and other living counterparts, helping to filter gases and air that move through the system. Of growing interest, is also the fact that fungi could have a major role in soil carbon sequestration.
Soil carbon sequestration is the process of transferring carbon dioxide from the atmosphere into the soil in a form that is not immediately reemitted.
Leucocoprinus fungi
For the past four years, Egerton-Warburton and colleagues at Northwestern University have been working to better understand the flow of carbon through fungal communities that results in long-term soil carbon sequestration. Soil’s capacity to store carbon is a reason for hope and a potential way to mitigate climate change. According to Egerton-Warburton, soil is known to hold three times more carbon than plants and trees above ground. “Maybe there are other ways we can manage the systems and enhance that capacity in the soil,” she said.
The study has required a lot of ‘getting to know you’, as the researchers first sought to identify each type of fungi involved in the process of carbon sequestration. As plant parts above ground are faced with absorbing and converting larger and larger amounts of carbon dioxide from our atmosphere into sugars, and sending it down into their roots, the more beneficial it will be to have a healthy suite of fungi waiting to receive it, use it, and move it along for future long-term storage.
Part of this equation has been to understand which fungi benefit from the increasing supply of sugar. Previous work by Egerton-Warburton has shown that mycorrhizal fungi respond to increases in atmospheric carbon dioxide by producing large quantities of hyphae, a fine root-like structure, in the soil. This is because increases in atmospheric carbon dioxide allow a plant to produce more sugars during photosynthesis, and these sugars are shunted below ground for use by roots and their mycorrhizal fungi. At the other end of the equation are saprophytic and decomposer fungi, waiting to break down the new hyphae.
Recent work in the Dixon Prairie has used the high throughput sequencing and chemical fingerprinting to identify the fungi involved in this decomposition phase. Once that is resolved, they will be able to better understand how the fungi interact and balance the cycle carbon through specific pathways of activity..
Louise Egerton-Warburton at work in the soil lab
The more the merrier, when it comes to fungi, and when it comes to people who are willing to help them endure, said Egerton-Warburton. The scientist often works with students who are interested in careers in the field, but encourages additional people to consider this critical line of work. “There’s a real need for soil ecologists in the country,” she said.
The good news is that the future story of fungi is one we can all help to script. Gardeners, she advised, can pay attention to the type of mulch they use in their garden, and plant lots of native species that will naturally enrich the function of that wonderful world that holds us up.
The clock was ticking—a little girl was seriously ill—when I got the call for help. A Denver hospital needed living tissue from Thujopsis dolabrata or any of its cultivars within 24 hours to determine if the plant was the cause of the girl’s life-threatening allergic reaction.
Don’t call us first! Call the U.S. Poison Control Center at (800) 222-1222. If you need help identifying a plant to determine if it’s poisonous—and it’s not an emergency—try our Plant Information Service at (847) 835-0972. Please bring in a live plant sample for an accurate identification.
The girl had been flown in from Japan to be treated at the hospital, National Jewish Health. After I got the call, I looked into the hospital, which is known worldwide for treating patients with respiratory, immune, and related disorders. In the girl’s case, the doctors apparently had a list of potential allergens they were testing, including Thujopsis, a rare evergreen shrub that is native to Japan.
A hospital official began the search for the plant with a colleague of mine at the Denver Botanic Gardens. My colleague met the girl’s grandmother, who showed her a picture of the patient’s red and inflamed face. When my colleague couldn’t help, she checked around and found via the Chicago Botanic Garden’s free smartphone app, GardenGuide, that we have the plant, commonly known as hiba arborvitae.
While the call came out of the blue—in my 17 years at the Garden, I’ve never fielded such a request—this type of emergency was not new to me. I used to be in charge of landscaping at the University of Texas Medical Branch in Galveston, and occasionally supplied plant samples from the campus gardens to the Texas Poison Control Center. Now, as the Garden’s director of living plant documentation, the response just kicked in.
In the Garden’s production nursery, I snipped a branch from two different cultivars of Thujopsis. Within three hours of receiving the request, I had dropped the samples off at FedEx on the way home.
As it turned out, Thujopsis did appear to be the culprit, and the hospital is continuing to test the girl’s blood samples with extracts from the Thujopsis to determine what constituents are causing the allergic reaction (the same constituents can be found in related species, so the search to identify other potential sources is prudent). Meanwhile, the girl responded quickly to emergency treatment, was stabilized, and returned to Japan.
While public gardens and other outdoor spaces are often recognized for their mental health benefits, this incident reminded me of the fact that botanic gardens have made important contributions to the physical well-being of people in need.
For more than 450 years, botanic gardens have collected and housed plants from throughout the world for the public good, from medicinal plants in the sixteenth century to food crops used to expand and improve people’s diets (like potatoes, tomatoes, and corn introduced to Europe from the New World, and global economic plants like tea and cocoa). I’m proud to be a part of this history.
Alexandra Seglias is a second-year master’s student in the Plant Biology and Conservation program at Northwestern University/The Chicago Botanic Garden. Her research focuses on the relationship between climate and dormancy and germination of Colorado Plateau native forb species. She hopes that the results of her research will help inform seed sourcing decisions in restoration projects.
