60-Second Science: Phylogenetic Trees

PHOTO: Dr. Evelyn Williams, Conservation Scientist.Dr. Evelyn Williams is an adjunct conservation scientist at the Garden. She’s interested in genetic diversity at multiple scales, from the population to the family level. While at the Garden, Dr. Williams has worked on rare shrubs from New Mexico (Lepidospartum burgessii), systematics of the breadfruit family (Artocarpus), and using phylogenetic diversity to improve tallgrass prairie restorations.


When a scientist says that chimpanzees are related to humans, or that chickens are related to dinosaurs, what do they mean?

They mean that chimpanzees and humans share a common ancestor from many thousands of generations ago. Although that shared great-great-great-great-(etc.)-great-parent lived many years ago, that shared ancestor lived more recently than the ancestor that humans share with dogs. So humans are more closely related to chimpanzees than dogs because they have the most recently shared ancestor. Scientists call this the “most recent common ancestor.”

This most recent common ancestor wasn’t a chimp, and it wasn’t a human—it was a different species with its own appearance, habits, and populations. One of these populations evolved into humans, and one of the populations evolved into chimpanzees. We know this because of a field of study called “phylogenetics.” Scientists use phylogenetics to study how species are related to each other. 

Phylogenetic tree diagram.

Using DNA sequences, scientists construct tree-like diagrams that trace how species are related. A human’s DNA is more similar to a chimpanzees’ than to a chicken, so a tree diagram would connect humans and apes. Dinosaurs and chickens would be shown as related as well, and then these two groups would be connected.

Interested in learning more? Explore phylogenetics with the Tree of Life Web Project. Dig deep into the study of the phylogenetic roots of food plants with The Botanist in the Kitchen


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 fourth installment of their exploration.

©2016 Chicago Botanic Garden and my.chicagobotanic.org

Living Monuments: Inside the White House Kitchen Garden

President’s Day was established in 1885 as a day to celebrate all U.S. presidents past and present. It also seems to be just the right day for me to share the highlights of my visit to the White House with you.

Smack dab in the middle of last fall’s Cubs playoff series against the Mets, on the same day that Vice President Joe Biden walked into the Rose Garden to announce to the world that he would not be pursuing a run for the White House, I was…well, I was there in that hardworking garden. I’d been invited to visit the vegetable garden at the White House and tour the grounds. I repeat, I was at the White House visiting the First Lady’s Kitchen Garden!

PHOTO: Lisa Hilgenberg in the White House Kitchen Garden.
Cool season vegetables and herbs planted in the White House Kitchen Garden
PHOTO: The White House beehive.
The White House beehive supplies the first family with honey.

The White House is “The People’s House” and its garden is the iconic “America’s garden.” I’d come on a visit facilitated by Andrew Bunting, director of plant collections and assistant director of the Chicago Botanic Garden—a fresh leader in a generation of garden advocates, a man with gardening friends in high places, possessing the ability to cut through red tape with a machete (stealing a lyric from a Cake song). The White House gardener, Jim Adams, graciously received me as a consultant for the White House Kitchen Garden, an arrangement we’d made when he visited the Regenstein Fruit & Vegetable Garden only a month before.

Established in 1791, the President’s Park is the official name for the 82 acres surrounding the White House. Originally laid out by Pierre Charles L’Enfant, a Frenchman who fought in the War of Independence, the French formal perspective stands today much as it was planned. Working with George Washington, a farmer and horticulturist, together they envisioned the official residence surrounded by a botanical garden, and the building began.

John Adams became the first president to occupy the White House in 1800, and he requested that a vegetable garden be plowed as a means to supply fresh produce for the nearly 30 people he was responsible for feeding. His request was never realized as he lost his bid for reelection to none other than America’s founding gardener, Thomas Jefferson. Our third president had a strong interest in plants and took on the planting of specimen trees around the grounds and cultivated figs, strawberries, orange trees, and his favorite geraniums inside his sunny office. While none of his trees survive today, it was he who planted rows of sycamore, poplar, and cedar with oak, chestnut, and linden trees on the north side of the White House. (The south grounds were more private and pastoral in design, and eventually iron fences secured the interior 18 acres of private garden around the house, dividing it from the public garden.) Today, 500 trees thrive within this iron fence.

PHOTO: Jimmy Carter's Cedar of Lebanon, planted in 1978.
Jimmy Carter’s Cedar of Lebanon, planted in 1978

As one of the earliest proponents of forestry in the United States, President John Q. Adams planted an American elm (Ulmus Americana) in 1826. (With all the monumental trees, there is a succession plan, so when it needed to be removed in 1991, Barbara Bush’s propagated replacement was planted in the same place.) In 1830, President Andrew Jackson planted the famous Magnolia grandiflora. President Rutherford B. Hayes planted Ohio buckeyes (Aesculus glabra) in honor of his home state. Hayes was the president who introduced the idea of planting commemorative trees to honor presidential tenure or upon historical events. He wanted a tree representing each president and his state as well as each state in the Union. Today, 40 commemorative trees stand on the grounds, cultivated to be excellent specimens of their genus.

PHOTO: Under the Jackson southern magnolias (planted in 1830).
Under the Jackson southern magnolias planted in 1830

President Dwight D. Eisenhower planted northern red oak, Quercus rubra in 1959, President John F. Kennedy planted four Magnolia × soulangeana in 1962. President Clinton planted a pair of white dogwoods, Cornus florida, and President Barack Obama planted littleleaf linden Tilia cordata in 2009—the same tree President George H.W. Bush planted with Queen Elizabeth II in 1991. I held the shovel that commemorates the day each president dug the first shovelful of soil to plant his great tree!

As we walked around the grounds, passing by the putting green and the basketball court, the deeply personal nature of this botanic backyard garden became clear. I could only imagine the solace the garden provided to the families and children while they lived here. This was most evident in the intimate Children’s Garden that had been added to the south lawn by Lady Bird Johnson. Many of the presidents’ grandchildren have impressions of their hands of the paths of this secret garden.

Making our way down to the southwest corner of the lawn, we finally arrived at the White House Kitchen Garden. Centuries ago, President John Q. Adams planted fruit trees, herbs, and vegetables on the grounds; First Lady Michelle Obama was the first to plant vegetables since the Roosevelts planted a Victory Garden at the White House.

The four-season garden is grown in raised beds planted with more than 50 varieties of seeds, many of them heirlooms. One of the beds commemorates the varieties Thomas Jefferson planted in his garden at Monticello. Heirloom lettuce, brussels sprouts, beets, kale, and artichoke seed have been saved and passed down in preservation of our agricultural history. Mrs. Obama intended the garden to be an instructional space, emblematic of her concerns about food security, childhood obesity, and her Let’s Move initiative. I had a chance to meet Cris Comerford, White House chef, in the kitchen to confirm that the bountiful garden harvest is regularly used for State dinners and family dinners.

PHOTO: The White House Weather Station.
The weather station in the White House Kitchen Garden

The White House gardener of today is a weather watcher, as the founding fathers and colonial gardeners were. A rain gauge was installed in the First Lady’s vegetable garden in March of this year, where it not only informs the schedule for watering the lawn but also monitors amounts and reports to the largest Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS). It collects precipitation amounts while also contributing to a broader citizen science effort documenting regional weather patterns and snow.

Just as we got the word of the impending press conference in the Rose Garden, we needed to clear the grounds. On our way back in, I noticed a silver plaque on a pillar and marveled at the affectionate handwritten note, thanking Jaqueline Kennedy from those who worked with her in the White House.

PHOTO: The Jacqueline Kennedy dedication plaque in the White House garden.
“This garden is dedicated to Jacqueline Kennedy with great affection by those who worked with her in the White House-” April 22, 1965
PHOTO: Lisa Hilgenberg with presidential dogs.
I asked Bo and Sunny not to dig in the garden. Only Sunny needed a leash (which is appropriately patriotic)!

My memories galvanized forever in my heart, I’ve returned to the Regenstein Fruit & Vegetable Garden with a new appreciation for our connection to the broader national perspective of growing food as a democratic expression of individuality, health, wellness, self-reliance, and honor. This President’s Day, we can feel proud that our work at the Garden is part of this national movement.


©2016 Chicago Botanic Garden and my.chicagobotanic.org

Ancient & Modern: Two Love Stories, One Fantastic Orchid

On this Valentine’s Day weekend—which also marks the opening of the Orchid Show!—we share two tales of love, both about the same ravishingly beautiful flower, commonly called the Lady’s Slipper Orchid.

The first story has its roots in the ancient Greek myths. Flower legend says that the goddess Aphrodite (Venus to the Romans) was out hunting with the handsome mortal Adonis, when a powerful storm forced them to seek shelter together in a cave. Love ensued. Post-storm, the lovers ran off—Venus, minus one slipper. A mortal human came across the shoe and reached down to pick it up, when suddenly and magically it transformed into a flower with a slipper-shaped petal of gold.

PHOTO: Orchid in bloom.
Cypripedium calceolus slipper orchid

The Lady’s Slipper orchid’s beautiful binomial (two-part) Latin name, Cypripedium calceolus, was given it by none other than Linnaeus himself (Carl von Linné), who listed it in Species Plantarum in 1753. The great botanist packed a lot of meaning into that name: Cyprus was the sacred island of Venus’s birth, pedilon is the word for slipper, and calceolus means little shoe.

The Lady’s Slipper orchid is native to a broad swatch of the temperate world, from Europe through Asia. While still common in some wild areas, the orchid’s beauty has made it over-loved in others—it is now considered extinct in Greece, the very home of its ancient legend.

And that brings us to our second love story.

The flower fervor that swept through Britain in the nineteenth and early twentieth centuries not only raised demand for the exotic plants of the world but also took a toll on the native plants of the English countryside. Loss of habitat and over-collection by humans diminished the native Lady’s Slipper Orchid’s numbers until, in the early 1980s, just one plant remained in the wild in the entire country.

PHOTO: "Orchid-gami" of a showy lady's slipper orchid.
Make your own lady’s slipper orchid—no watering required! Just print this 2-sided template from the NAOCC, cut, and fold!

Placed under last-resort protection, it was nurtured along until it gained strength and eventually bloomed. Its seeds were collected and sent to Royal Botanic Gardens, Kew, where a conservation program was put into place. Eventually, the difficult-to-germinate seeds germinated. Seedlings, which take 5 to 10 years to flower, have since been re-introduced into the wild in an attempt to re-populate the species there.

This modern-day love story has devotion and commitment and conservation at its heart.

At the Orchid Show, you’ll learn more about the orchid conservation efforts that the Chicago Botanic Garden is committed to—including the work of the North American Orchid Conservation Center, which sponsors a terrific website about our continent’s native orchids at goorchids.northamericanorchidcenter.org.

PHOTO: Cypripedium Gisela gx Lady's Slipper orchid.
This Cypripedium Gisela lady’s slipper cultivar can be found blooming in the Heritage Garden in late May.

While there won’t be any Cypripedium calceolus plants in bloom at the Orchid Show (they’re terrestrial orchids that don’t bloom until spring), lots of other slipper orchids in the Paphiopedilum and Phragmipedium genera will capture your imagination and attention.

Take a selfie with your favorite and share it #theorchidshow @chicagobotanic. Hashtag your favorite orchid #cbgOrchid16 to enter our Instagram photo contest. Want to learn more about orchids? Read our blog posts!

And have a Happy Valentine’s Day, everyone!

60-Second Science: Prairies Need Fire


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

The Hidden Partners of the Vanilla Orchid

Vanilla cookies, vanilla perfume, and everything vanilla swept through my nostrils at a scented display at last year’s Orchid Show. The sweet smell was a great way to show many visitors that vanilla comes from the fruits of the vanilla orchid (Vanilla planifolia).

PHOTO: Orchid pods on the farm have dates scribbled on them in permanent marker, to help estimate a harvest date.
What are the scribbles about? Orchid pods are dated to estimate how long the pods have been on the vine, possibly to determine a good time to harvest them.

As a docent at last year’s show, I was eager to show off the Garden’s vanilla plant (located in the Tropical Greenhouse next to the banana trees), because I knew that may visitors didn’t know that they had an orchid in their spice cabinet.

Currently, I am in the second year of my research of the vanilla orchid. Vanilla is an exciting plant to study because it grows as a vine with two different types of roots. These roots help vanilla grow as a vine (more precisely a hemiepiphyte) because terrestrial roots anchor it within the soil, and epiphytic roots anchor it to tree trunks. My last post, Vanilla inhabitants: The search for associated bacteria and fungi, showcased my ongoing experiment in Mexico. This included collecting roots from four different Mexican farms that had very different practices for how they grew the orchid. We know that vanilla orchids use their epiphytic roots for support, but what other functions do they perform? Do they also form symbiotic relationships with fungal partners to obtain nutrients and water, like terrestrial roots?

Monocultures—crops with genetically identical heritage—are common in vanilla cultivation.

PHOTO: Many vanilla plantations use man-made structures for the vining orchids. Here, an old tree provides support to this orchid.
Many vanilla plantations use man-made structures for the vining orchids. Here, an old tree provides support to this orchid.

The fungal partners of orchids, known as mycorrhizal fungi, help an orchid start its life by providing needed nutrients for its seeds to germinate. No orchids in the wild can germinate without one or more mycorrhizal fungi. As a scientist, my goal is to study the interactions that the vanilla orchid has with these fungi as they mature. This is important because most vanilla farms are monocultures—it is easier to obtain clones from cuttings of vanilla than to germinate them from seeds. This, however, creates serious problems, because farms that have low genetic diversity in their vanilla orchids can lose their entire crop if a disease (such as root rot caused by Fusarium) appears.

Prior reports based on classic techniques have documented two or three species of mycorrhizal fungi within vanilla roots. In addition to these mycorrhizal fungi, there are also fungal pathogens (fungi that cause disease) and fungal endophytes (fungi that seem to have a mutualistic relationship with the host) that colonize a vanilla’s root.

To further investigate the situation, I ran an experiment using the latest DNA technology—Next Generation Sequencing (NGS)—to document the communities of fungi within terrestrial and epiphytic vanilla roots.

As fungal endophytes take up nutrients from their host, the mycotoxins they produce reduce herbivory and susceptibility to pathogens.

PHOTO: A length of canopies shields the growing vanilla orchids from harsh direct sunlight.
A length of canopies shields the growing vanilla orchids from harsh direct sunlight.

I documented 142 species of fungi associated with vanilla roots from the four Mexican farms, with an average of nine fungi colonizing a single vanilla root at one time. Of these 142 species, 20 are likely mycorrhizal. I find that fascinating, because these mycorrhizal fungi were found within both root types and across all farms. It was also surprising to know that epiphytic roots have a similar diversity of mycorrhizal fungi as terrestrial roots even though the epiphytic roots were green and could photosynthesize and have been considered primarily as support structures.

My study also documented a high number of previously unreported species of fungal pathogens and fungal endophytes colonized the roots of vanilla plants. This means that if plants are unhealthy, fungal pathogens likely can quickly take over, because they are already present within the roots. Overall, vanilla roots have good and bad partners just like we do, but contain more beneficial fungi (fungal endophytes and mycorrhizal fungi) than previously believed. These beneficial fungi not only supply the plant with water and nutrients, but also help control fungal pathogens. Thus, they are essential for plant health.

This research is funded with support from Mexican collaborators as part of the SAGARPA-CONACYT-SNITT 2012-04-190442 Mexican Vanilla Project.

PHOTO: Vanilla planifolia (vanilla orchid) in bloom.

Learn more about the orchids in your kitchen cabinet with our Vanilla Infographic; read up on another edible orchid in A Sip of Salep. Stay tuned for more orchid research projects, amazing orchid displays, and fun facts on our blog. The Orchid Show opens February 13!


©2016 Chicago Botanic Garden and my.chicagobotanic.org