Archives For plant science


PHOTO: Becky Barak.Becky Barak is a Ph.D. candidate in Plant Biology and Conservation at the Chicago Botanic Garden and Northwestern University. She studies plant biodiversity in restored prairies, and tweets about ecology, prairies, and her favorite plants at @BeckSamBar.


A dark, stinky plume of smoke rising from a nature preserve might be alarming. But fire is what makes a prairie a prairie.

A prairie is a type of natural habitat, like a forest, but forests are dominated by trees, and prairies by grasses. If you’re used to the neatly trimmed grass of a soccer field, you may not even recognize the grasses of the prairie. They can get so tall a person can get lost.

Prairies are maintained by fire; without it, they would turn into forests. Any chunky acorn or winged maple seed dropping into a prairie could grow into a giant tree, but they generally don’t because prairies are burned every few years. In fact, fossilized pollen and charcoal remains from ancient sediments show that fire, started by lightning and/or people, has maintained the prairies of Illinois for at least 10,000 years. Today, restoration managers (with back up from the local fire department), are the ones protecting the prairie by setting it aflame.

PHOTO: Chicago Botanic Garden ecologist Joah O'Shaughnessy monitors a prairie burn.

Garden ecologist Joan O’Shaughnessy monitors a spring burn of the Dixon Prairie.

PHOTO: New growth after a prairie burn.

New growth emerges a scant month after the prairie burn.

Prairie plants survive these periodic fires because they have incredibly deep roots. These roots send up new shoots after fire chars the old ones. Burning also promotes seed germination of some tough-seeded species, and helps keep weeds at bay by giving all plants a fresh start.

Read more about our conservation and restoration projects on the Chicago Botanic Garden website. Want to get involved in our local ecosystem conservation? Find your opportunity with Chicago Wilderness.


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. This is our third installment of their exploration.

©2016 Chicago Botanic Garden and my.chicagobotanic.org

PHOTO: Alicia Foxx.Alicia Foxx is a second-year Ph.D., student in the joint program in Plant Biology and Conservation between Northwestern University and the Chicago Botanic Garden. Her research focuses on restoration of native plants in the Colorado Plateau, where invasive plants are present. Specifically, she studies how we can understand the root traits of these native plants, how those traits impact competition, and whether plant neighbors can remain together in the plant community at hand.


Life for plants on land is hard because the environment can become dry. Water is important because it is used when plants take in sunlight and carbon dioxide to make energy; this is called photosynthesis. In fact, the largest object in a plant cell is a sack that holds water. Without water, plants would die.

Plants first evolved in water, which is a comfortable place: there is little friction, you almost feel weightless, and…there was plenty of water back then. These plants had no difficulty photosynthesizing, as water diffused quite easily into their leaf cells! They had little use for roots.

Evolving Plant Structures

In the time plants evolved to live on land (100 million years later), water shortages and the need to be anchored in place became issues and restricted plants to living near bodies of water. Some plants evolved root-like structures that were mostly for anchoring a plant in place, but also took in some water.  

It wasn’t until an additional 50 million years after the move on to land that true roots evolved, and these are very effective at getting the resources essential for photosynthesis and survival. In fact, the evolution of true roots 400 million years ago is associated with the worldwide reductions in carbon dioxide, since more resources could be gathered by roots for photosynthesis. Importantly, plants were no longer tied to bodies of water!

PHOTO: tree roots.

Large roots anchor a plant in place.

PHOTO: bulb with tiny bulblets and root hairs.

Tiny root hairs on a bulb take up nutrients when moisture is present.

Water issues continued, however, even with true roots. Early roots were very thick and could not efficiently search through the soil for resources. So plants either evolved thinner roots, or formed beneficial associations with very tiny fungi (called mycorrhizal fungi) that live in the soil. These fungi create very thin, root-like structures that allow for more effective resource uptake. In general, while life on land is hard, plants have evolved ways to cope via their roots.

Garden scientists are studying the relationships between plants and mycorrhizal fungi in the soil. Orchids are masters of nutrient collection. The vanilla orchid has terrestrial (in soil) and epiphytic (above ground, or air) roots—and forms relationships with fungi for nutrient collection. Read more about research on Vanilla planifolia here


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. This is our second installment of their exploration.

©2016 Chicago Botanic Garden and my.chicagobotanic.org

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.


PHOTO: Alexandra Seglias at work in the field.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.


PHOTO: A tiny oak sprouting from an acorn.

A tiny oak emerges from an acorn. Photo by Amphis (Own work) [CC BY-SA 3.0], via Wikimedia Commons


Dormancy and Germination

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.

Our scientists are studying seed germination in a changing climate. Learn how you can help efforts to help match plants to a changing ecosystem with the National Seed Strategy


©2016 Chicago Botanic Garden and my.chicagobotanic.org

Spike’s Teachable Moment

What was happening with Spike? Our scientists investigate.

Karen Z. —  August 30, 2015 — 6 Comments

What an amazing plant science moment occurred in the Semitropical Greenhouse this morning, as a fascinated crowd gathered to see what was happening with Spike, the titan arum.

On Saturday, it was determined that Spike had run out of the energy it needed to continue its bloom cycle. Spike is powered by energy from the sun, stored in its beach-ball-sized corm—a tuber-like underground structure. A tremendous amount of energy goes into producing the single, giant flower structure that a titan can send up in its first decade or so of life (Spike is about 12 years old).

Overheard: “I wish my biology teacher was here.”

As this week’s expected bloom time passed, our science and horticultural staff went into action. Spike wasn’t dying—but the flower structure had stopped maturing, and the spathe did not open. On Friday, Dr. Shannon Still, conservation scientist, and Tim Pollak, the floriculturist who had raised Spike from a seed, peeked inside the frilly spathe to check for pollen.

“If there had been pollen, it would have been all over my hand,” Still said. Pollen’s absence meant that the male and female flowers might not be fully developed. The possibility remained that pollen might still develop, even though the spathe would not open—and THAT led to the decision to remove the “frozen” spathe to see what was happening with the real flowers inside.

Overheard: “We were watching it every day. Every 20 minutes or so.”

First, Still assembled a working kit: scalpel, probes, test tubes, paintbrushes and a “scoopula” (to collect pollen).

At 10 a.m. today, staff gathered for the delicate procedure. Pollak and Still fist bumped…and the operation began. 

As Still began cutting just above the peduncle (stalk), the crowd grew quiet. Dr. Pat Herendeen, senior director, Systematics and Evolutionary Biology, narrated for the crowd. As the spathe started to come away from the towering spadix, the internal color started to be visible.

Left: a cross-section of the spathe reveals the cell structure inside. Right: close-up on the hundreds of male (top) and female (bottom) flowers inside Spike's spathe.

Left: A cross-section of the spathe reveals the cell structure inside. Right: A close-up of the hundreds of male (top) and female (bottom) flowers inside Spike’s spathe.

“The spathe feels a bit like cabbage leaves, with a rubbery texture,” Herendeen said. “The color inside varies from one plant to another in nature. It is dark maroon, the color of rotting meat, which is meant to attract the flies and beetles that are the plant’s natural pollinators.”

Pollak held the spathe steady as Still continued to free it from the stalk. With one last cut, it came free—and the crowd gasped as the inside of the spathe was unfurled and the true flowers at the base of the spadix were revealed—pale rows of bumpy-looking male flowers atop a strip of orange and brown female flowers.

Tim Pollak and Shannon Still make the first cut.

Left: Tim Pollak and Shannon Still make the first cut. Right: Tim Pollak reveals the spathe’s ravishing color.

Herendeen answered as questions flew: The male flowers do not appear to have produced pollen yet. Spike’s fabled scent is only detectable very close up to the spathe—much less apparent than it was earlier in the week.

Cameras focused in on the flower structure, as Still and Pollak carried the two large pieces of the cut-away spathe over to the crowd. Hands reached out for a touch; noses leaned in for a sniff. Spike’s spathe was set out on a gallery table so that everyone could touch and admire it before it begins to wilt.

Overheard: “Spike was the topic of dinner conversation with our two sons every night for the past week.”

While television camera crews stepped in for close-ups on the plant’s flowers, interviewers questioned the scientists: Where does the scent come from? (It’s believed that the tall appendix helps produce the scent, though scientists are also investigating the female flowers themselves.) Would Spike bloom again? (Probably, but the corm would have to recover first, by sending up an annual leaf for a few years to gather more energy.)

Cross-legged on the floor opposite Spike sat Chicago artist Heeyoung Kim, who sketched intently during the entire process. Her intricate pencil markings captured Spike’s pleats and tightly clustered flowers—the beginnings of a botanical illustration that could inform future scientists studying the titan arum’s beautiful structure for years to come.

We have been so thrilled with the intensity of interest in Spike—it’s not every day that crowds gather to watch a plant grow! We’ll continue to keep you posted about possible pollen development, our scientists’ thoughts about Spike’s arrested development, and on the progress of the eight other titan arums now growing in our production greenhouses. 

Left: what a great vibe! Right: Kris Jarantoski explains Spike's spathe to a young visitor.

Left: What a great vibe from the gathered crowd! Right: Kris Jarantoski, executive vice president and director, explains Spike’s spathe to a young visitor.

For more information please visit our titan arum page.

©2015 Chicago Botanic Garden and my.chicagobotanic.org

Popular culture moves in strange ways. Since the release of the eponymous movie, the idea of a “bucket list” has quickly become part of our modern vernacular.

My botanical bucket list includes plants like the ancient bristlecone pines of Nevada and the cobra-lilies of Northern California. Recently, in the Peruvian Amazon, I checked off my list the giant Amazonian waterlily. I’ve seen it many times before; it is grown all over the world. But coming across it in an Amazonian backwater, untended by people, is quite a different experience. 

PHOTO: Victoria amazonica, the giant Amazonian waterlily.

The giant Amazonian waterlily (Victoria amazonica), with its magnificent leaves beautifully arrayed like giant solar panels in the tropical sun

Plants like Amazonian waterlilies, bristlecone pines, and cobra-lilies have a presence. Even brief contemplation invokes a sense of wonder, and sometimes an emotional, even spiritual, connection. These charismatic plants are tangible expressions of the glory and mystery of nature. And paradoxically, that sense of mystery is undiminished by scientific understanding. As Einstein once said, “What I see in Nature is a magnificent structure that we can comprehend only very imperfectly, and that must fill a thinking person with a feeling of ‘humility’.” 

The Amazonian waterlily is one of the botanical wonders of the world, but look closely and every plant has its own mysterious life story full of evolutionary twists and turns. Whether in the garden, in the forest preserve, or along the roadside, even the most inconspicuous weed is a twig atop the gnarled and much-ramified tree of life. Every plant is a living expression of the vicissitudes of thousands, often millions, of years of history. 

PHOTO: Guest columnist and Garden board member Peter Crane, Ph.D.

Guest columnist and Garden board member Peter Crane, Ph.D.

Over the past three decades the evolutionary tree of plant life has come into clearer focus, as we have learned more about living plants, including about their genomes. We have also learned more about plants of the past by exploring their fossil record. There is still much that remains beyond our grasp, but scientists at the Chicago Botanic Garden are at the forefront of current research, including efforts to integrate information from fossils and living plants toward a more complete understanding of plant evolution. And viewing the world’s plants through an evolutionary lens only accentuates our sense of wonder. The leaves and the flowers of the Amazonian waterlily are massively increased in size and complexity compared to those of its diminutive precursors, which begs further questions about why and how such dramatic changes occurred. 

To borrow a phrase from Darwin, “There is grandeur in this view of life.” Such perspectives, rooted in deep history, emphasize the power and glory of evolution over vast spans of geologic time, as well as its remaining mysteries. In the face of rapid contemporary environmental change, they also underline the need for enlightened environmental management. Looking to the past to help us understand the present sharpens our view of the glories of nature. It also reminds us of our place in the world, and the value of humility as we together influence the future of our planet. 

Renowned botanist Sir Peter Crane is the Carl W. Knobloch, Jr. Dean, Yale University School of Forestry & Environmental Studies and former director of the Royal Botanic Gardens, Kew. Dr. Crane is also a life director of the board of the Chicago Botanic Garden. In 2014 Dr. Crane received the International Prize for Biology, administered by the Japan Society for the Promotion of Science, for his work on the evolutionary history of plants. The award, created in 1985, is one of the most prestigious in the field of biology.

This post is a reprint of an article by Sir Peter Crane, Ph.D. for the summer 2015 edition of Keep Growing, the member magazine of the Chicago Botanic Garden. ©2015 Chicago Botanic Garden and my.chicagobotanic.org