Using Genetics to Rescue a Rare Desert Shrub

Huddled on a sand dune, the small community of bristly Lepidospartum burgessii plants would be easy for most of us to overlook. But to scientists from the Chicago Botanic Garden, the rare shrubs shine like a flare in the night sky. This is one of two known locations of the species worldwide—both in New Mexico—and the center of a rather dazzling rescue mission.

Evelyn Williams, Ph.D., a Garden postdoctoral research associate, is pulling out all the stops to save the sensitive species. Commonly called Burgess’ scale broom, it has suffered from a mysterious lack of seed production since the late 1980s.

PHOTO: Burgess' scale broom (Lepidospartum burgessii).
Burgess’ scale broom (Lepidospartum burgessii) are among the tallest plants in their New Mexico location.

Standing about five feet tall, the silvery-green plants only grow on gypsum dunes. They possess unique characteristics that allow them to help stabilize sand dunes in the desert conditions where they live.

“I’m interested in how we can use genetics broadly to address conservation and ecological restoration questions,” said Dr. Williams. Her curiosity led her to the Garden in 2011 to join a team of genetic experts for this formidable undertaking.

The team suspects that, because the two populations of Lepidospartum burgessii are relatively small, the existing plants have interbred and are now too closely related to pollinate one another—which means they cannot produce seeds and create new plants.

Williams set out to confirm this theory, gathering plant cuttings during summer fieldwork in 2013. She hoped to grow the cuttings into full plants that she could cross-pollinate and study at the Garden. She also took samples from 320 plants back to the Garden. There, using a microsatellite technique, she recorded the genetic pattern of each plant, noting similarities and differences.

“When we have all of these different shrubs from a population, we want to use a fine genetic tool to tease apart genetic variations,” she explained. The microsatellite approach allowed her to identify genetic markers occurring in multiple plants down to the finest level of detail.

The results were encouraging. Williams found enough genetic diversity within the two populations that they should be able to cross pollen, or DNA material, and produce seeds. “Because there is diversity in these populations, we’re really hopeful that if we do a genetic rescue we can get some seeds in these two different populations,” said Williams. A genetic rescue, she explained, is when a species is revived with the addition of new genes, which normally occurs during pollination.

That day didn’t come right away, as the cuttings failed to grow in the Garden greenhouses. Accustomed to the trial and error process of scientific discovery, Williams moved on to her backup plan.

PHOTO: Dr. Williams hand-pollinating a specimen.
Evelyn Williams, Ph.D., delivers pollen to a plant.

She returned to the field in October, where she personally carried pollen-filled flowers from one population of plants to another, brushing the fluffy yellow blooms against other plants that may accept their genetic material. With plants as much as one mile apart, it was a process of patience and precision.

She will soon look for seeds in the resulting buds from that pilot study with an x-ray machine in the Garden’s Harris Family Foundation Plant Genetics Laboratory.

Williams is poised for the challenge of whatever she may, or may not, find. Ultimately, she hopes to convey a successful technique to land managers who carry out the daily work of furthering the species and enriching the biodiversity of the southwestern landscape.

“I really like that as part of the Garden we can help these public agencies and use our knowledge of genetics and conservation to stabilize and increase some of these rare populations. That’s really important to me,” said Williams.

PHOTO: Lepidospartum burgessii, framed by the sunset.
Lepidospartum burgessii, framed by the sunset. Photo: Mike Howard

She has been intent on advancing conservation science since childhood, inspired by her aunt, an ecologist. Her interest grew into expertise as she studied the genetics of ferns while earning her Ph.D. in botany at the University of Wisconsin.

In winter at the Garden, Williams takes every opportunity to walk through the Elizabeth Hubert Malott Japanese Garden. “I like being here in the winter and seeing a side of the Garden that’s unexpected: the snow and the beautiful structures in the Malott Japanese Garden,” she said.

Perhaps it is that perspective, of looking for the unexpected, that will unlock the mystery of Lepidospartum burgessii one day soon.

©2013 Chicago Botanic Garden and

Treasure in the Tropics

Hungry for progress, Nyree Zerega, Ph.D., set off in early June to the forests of Sabah, Malaysia, on the island of Borneo.  She was searching for plants in the genus Artocarpus, whose nearly 70 species include jackfruit—the world’s largest tree-borne fruit structure.

Her mission? To gather detailed information about species within the genus, including those that could provide food in tropical areas where it is needed most.

PHOTO: Dr. Zerega and Dr. Joan Pereira climbing hill in tropical forest.
Dr. Zerega in Sabah with Dr. Joan Pereira, her Malaysian collaborator.

On their research trip this summer, Dr. Zerega, a plant evolutionary biologist at the Chicago Botanic Garden, and her research team crossed a small stream on their way into a tropical forest on the edge of a large oil palm plantation. They searched there for an uncommon species until sunlight faded and the light rain turned to a downpour. On the way back, they found that the stream had grown into a raging river several feet wide and deep. Covered in leeches, they held hands tightly and waded across to safety. On other days, they searched for species with leaves as tall as any one of them, and collected fruit weighing more than 20 pounds apiece.

The dish

It’s all in a day’s work for Zerega. She has long traveled to places like this, where she works closely with local scientists to study underutilized food-bearing plants.

PHOTO: Jeisn Jumian with a huge jackfruit over one shoulder, and a cut jackfruit in his other arm.
Jeisn Jumian, field assistant, carries jackfruit back from the field for dinner.

Currently, she explained, the world relies on roughly 30 species to provide the majority of our food. The top three crops—rice, corn, and wheat—account for approximately 40 percent of all food consumed worldwide. We are merely scratching the surface of the thousands of edible plant species in existence, including at least a dozen in the genus Artocarpus.

It’s possible, even likely, that some underutilized crops have as much potential as the current favorites, but simply have not been as developed. “Underutilized crops have the potential to diversify the world’s food supply and improve food security,” said Zerega. She believes the development of these crops, produced close to where they would be consumed, could also reduce the amount of energy used in growing and exporting large quantities of crops around the world. The more options we have, the better off we are, she maintains.

Stocking the pantry

Now back in the Harris Family Foundation Plant Genetics Laboratory of the Daniel F. and Ada L. Rice Plant Conservation Science Center, Zerega and her lab members are busy extracting plant DNA from leaves collected in Malaysia. Also the director of the Northwestern University and Chicago Botanic Garden Graduate Program in Plant Biology and Conservation, she has plenty of helping hands from her master’s and doctoral students.

“We’ll be studying DNA to understand the evolution of Artocarpus, and patterns of the diversity of cultivated members of the genus, such as jackfruit, breadfruit, and the lesser known cempedak, a species believed to have originated in Malaysia. Understanding and conserving genetic diversity is as critical in crop species as it is in wild species,” she said.

PHOTO: The market in Sabah, Malaysia.
Breadfruit is sold at a market in Sabah, Malaysia.

The work is part of a National Science Foundation grant for which Zerega is assembling a taxonomic revision, which is like a genealogical history. It will include descriptions of all the Artocarpus species, how to identify them, where they originated, where they are found today, how they are used, and how they are related to one another.  

Dried, pressed specimens of all the plant samples used for DNA will be stored in herbaria in Malaysia and the Garden’s Nancy Poole Rich Herbarium. Zerega serves as director of the herbarium. These specimens, along with photographs, serve as documentation of each plant.

Cooking up solutions

PHOTO: A plate of fried breadfruit with dipping sauce.
Fried breadfruit from a market near Kuala Lumpur, Malaysia.

Next, Zerega hopes “to focus on ways to conserve the diversity and increase the use of underutilized species such as jackfruit and breadfruit, because they hold great potential for increasing food security in food-insecure parts of the world, many of them in tropical areas where Artocarpus species grow.”

As she considers her research, Zerega occasionally finds time to stroll her favorite areas of the Garden—the Dixon Prairie and the McDonald Woods.

From working with students and collaborating with scientists around the world, she hopes her work will contribute to the conservation of underutilized crop diversity and food security around the world. Although she has already accomplished a great deal, it seems that Zerega’s work so far is just a taste of what is to come.

Read more about Zerega’s research in Papua New Guinea, the Northern Mariana Islands, Hawaii, and Bangladesh in the Spring 2013 issue of Keep Growing.

©2013 Chicago Botanic Garden and

Painting with Numbers

Emily Yates has covered a lot of territory.

Once a summer intern who collected plant seeds in North Dakota, she now manages an innovative mapping laboratory at the Chicago Botanic Garden. A scientist and artist, Yates translates massive amounts of data into accurate, colorful depictions to help researchers communicate their findings. Scientists, land managers, volunteers, and others use this information to help advance collective conservation goals.

Her newest project was freshly completed when we met in her office at the Daniel F. and Ada L. Rice Plant Conservation Science Center. It’s a project that has set the pace for modeling the immense database of the Plants of Concern (POC) program, and is likely to garner much attention at upcoming scientific conferences.

PHOTO: Hill's thistle and wooly milkweed in the field.
Hill’s thistle (Cirsium hillii) and wooly milkweed (Asclepias lanuginosa) are two of the rare plants monitored by the Plants of Concern program. (Milkweed photo ©Carol Freeman)

POC volunteers are citizen scientists who use GPS, global positioning systems, to gather geospatial data marking the location of rare plants in the Chicago area. “Part of what Plants of Concern wants to do is monitor, over time, changes in all the populations that are known of these rare plants,” said Yates, Seed Bank coordinator and conservation GIS Laboratory manager at the Garden.

Why rare plants? They have such specific environmental requirements and occur so infrequently, that they could be entirely lost if conditions change.

In late August, Yates wrapped up several months of work with a team including an intern with the Garden’s Research Experience for Undergraduates (REU) program. Together, they mapped the potential presence of Hill’s thistle (Cirsium hillii) and wooly milkweed (Ascelpias lanuginosa) across six northeastern Illinois counties monitored by POC. The two species are only known to grow in habitats characteristic of gravel hill prairies. The map was created using ten years of data on these two species.

MAP: Rare gravel hill species site suitability map.
Yates created this map to show areas where Hill’s thistle and wooly milkweed could occur.

“Sometimes with ecological data it’s easier to see things visually and spatially rather than in table format, and maps help to do that,” said Yates.

PHOTO: Trimble handheld device.
A Trimble is used to collect and plot geographical data of plant populations.

Looking at factors such as required soil type and land cover, they plotted locations where the plants have already been documented and used models to predict where the plants may exist due to favorable conditions. “Because these plants are rare, sometimes it’s very likely there are populations we haven’t found yet, so these maps can be very helpful in determining where to look,” said Yates. “GIS helps narrow [data] down and concentrate resources—enabling better land management decisions.”

What next? The paper the team generated will serve as a model for mapping the hundreds of other species monitored by POC, and it could be shared broadly through conferences and other means. Already, it was presented at the conclusion of the REU program.

Also, the project served as a valuable learning opportunity for the REU intern, who worked on the project in the GIS Lab with Yates, and in the field where he confirmed data records alongside scientists. Yates mentored an intern last summer as well, and is already thinking of the possibilities for next year.

According to Yates, “a lot of students express an interest in doing GIS projects because it is a skill that can be applied to a lot of different fields. Its focus on spatial thinking couples well with ecology and plant science, and it is a great, practical job skill to have.”

After completing her graduate studies, Yates expanded her own work to include a specialty in GIS. “My first love is nature and plants,” she said. “I became interested in how to look at plants and the natural world in a spatial context. I like the idea of cartography used for visualizing ecological patterns because it helps you see the connections.”

Learn more about Yates’s work and watch a video.

PHOTO: Emily Yates in the field.
Emily Yates in the field, gathering herbarium specimens.

Yates, who also teaches GIS and spatial analysis to students in the Northwestern University and Chicago Botanic Garden graduate program in plant biology and conservation, is already hard at work on her next project. She is creating the spatial component for a database of the Garden’s Dixon National Prairie Seed Bank, part of the National Seeds of Success program. “When you put the spatial component into [data], it kind of makes it come alive,” she said.

Summer isn’t all about work for Yates, who is also a gardener. It is the time of year when she most loves to visit the Regenstein Fruit & Vegetable Garden to find inspiration. When we talked in late August, she was already brimming with ideas for her garden next year. Surely, it won’t be long before she has it all mapped out.

©2013 Chicago Botanic Garden and

Weevil Warriors

A bracelet of pink-and-cream blooms borders Lake Michigan at this time of year. Growing up from barren, sandy areas, Pitcher’s thistle (Cirsium pitcheri) is like an oasis for nearby insects looking for nectar.

Helpful pollinators visit the plants often, but not nearly enough to offset the damage of the predatory visitors, according to Garden scientists, who hope to tip the balance in order to save the federally threatened plant species. It all began in 1997, when Kay Havens, Ph.D., joined a team of researchers to reintroduce Pitcher’s thistle to Illinois Beach State Park. But she wondered why a reintroduction was needed for a normally sturdy group of plants.

PHOTO: Adult weevils on Pitcher’s thistle plants in Door County, Wisconsin
Adult weevils on Pitcher’s thistle plants in Door County, Wisconsin

“Thistles as a group are typically pretty successful, even weedy, and it’s unusual to have a native thistle that is so rare,” said Dr. Havens, Medard and Elizabeth Welch director of plant science and conservation at the Garden.

Along with her Garden colleague, Pati Vitt, Ph.D., she found the plant is especially susceptible to a species of weevil (Larinus planus) whose larvae feast on emerging seeds. Unfortunately, if a blooming thistle loses its seeds before they are dispersed, new plants cannot be started.

“We were the first to document the weevil in this threatened thistle,” said Havens. “If we don’t find a way to control it, the plant is further threatened with extinction.” This discovery was followed by the identification of a second, equally destructive weevil (Rhinocyllus conicus) in Indiana Dunes State Park.

“The weevils have become very widespread in Pitcher’s thistle and they cut the seed output by about half,” said Havens. Both insect species, she explained, are biocontrol weevils that were intentionally scattered in the area for years in an effort to control the invasive Canada thistle (Cirsium arvense). Now, the damaging insects are off the list of solutions for Canada thistle.

As we talked, it was clear that this rescue team is not willing to accept defeat from a 7-millimeter bug. For years, they have been hard at work gathering information to help them arm the thistle against its adversary, and theorizing potential solutions.

Pitcher’s thistle lives four to eight years, and only blooms once, the conservation scientists told me. And they are also working to better understand the remarkable plant that has a custom set of strategies, like all plant species, to survive and reproduce.

“Every species represents a unique solution to an entire suite of environmental problems,” said Dr. Vitt, Susan and Roger Stone curator of the Dixon National Tallgrass Prairie Seed Bank at the Garden.

These solutions, she explained, could solve large-scale problems for people or other species in ways we don’t yet know. “The species has intrinsic value because it has these unique solutions that evolved over hundreds of thousands of years,” she added.

PHOTO: The research site in Wisconsin with flags marking study plants
The research site in Wisconsin with flags marking study plants

This summer, Havens and Vitt spent weeks in Door County, Wisconsin, observing the interactions of the weevil with Pitcher’s thistle, as well as those of its suite of pollinator species.

Watch a video to learn how Havens became interested in plants as a child, and why she says we couldn’t survive without them today.

Together with their research team, they recorded detailed notes about the frequency and time of visits by the helpful pollinators, like bees, and the dreaded weevils. In total, they monitored 27 visiting insect species.

“We want to find ways to protect this plant from weevils without affecting its pollinators,” said Havens. Could a certain floral scent do the trick? Could a natural insecticide be the answer? Each solution must be carefully tested and put to trial first.

For now, they are busy trying to understand the life cycle of the weevil as it relates to the thistle—from the time an adult lays its eggs in the seedhead to the time the larvae emerge from the flower and eat the seeds that could have been the next generation of plants.

As I left Havens and Vitt in the Daniel F. and Ada L. Rice Plant Conservation Science Center, they were sorting through their samples of seedheads and weevils, collected in the field, and musing over the potential solutions planted by their research that are just beginning to grow.

©2013 Chicago Botanic Garden and

Science Scents

Summer romance is in the air on the shortgrass prairie of southeastern Colorado. Quite literally, the alluring fragrance of Harrington’s evening primrose (Oenothera harringtonii) wafts in the breeze when the plant blooms each evening. Insects from bees to moths follow the scent to the flower of their dreams.

Dr. Skogen sets up floral-scent collection equipment for a previous experiment at the Garden.
Dr. Skogen sets up floral-scent collection equipment for a previous experiment at the Garden.

The insect’s choice of flower is significant to the future of the plant species, according to Krissa Skogen, Ph.D., Chicago Botanic Garden conservation scientist. After a pollinator lands on a plant and sips its nectar, it may carry a copy of a plant’s genes, in the form of pollen, to the next plant it visits. That next plant may then take those genes to combine with its own to form a seed—creating the next generation of Harrington’s evening primroses.

How do pollinators select a flower? According to Dr. Skogen, floral scent heavily influences their choices in addition to floral color and size. “Floral scent is this fascinating black box of data that a lot of reproductive biologists haven’t yet collected,” she said.

After studying the many pollinators of the evening primrose, from bees to moths, she found that two species of moths called hawkmoths—or more specifically, the white-lined sphinx moth (Hyles lineata) and the five-spotted hawkmoth (Manduca quinquemaculata)—are most effective. She told me that 30 percent more seeds are produced when a hawkmoth pollinates a plant rather than a bee.

Dr. Skogen and her team start their evening pollinator observations at dusk in Comanche National Grasslands.
Dr. Skogen and her team start their evening pollinator observations at dusk in Comanche National Grasslands.

“What’s really awesome about this system is that these hawkmoths can fly up to 20 miles in a night, while bees typically forage within one to five miles,” she added.

An insect so large it is often confused for a hummingbird, the brown-and-white hawk moths can carry genes between the widely spaced evening primrose populations.

A five-spotted hawkmoth visits Harrington’s evening primrose near Pueblo, Colorado.
A five-spotted hawkmoth visits Harrington’s evening primrose near Pueblo, Colorado.

In fact, Skogen has genetic data that support this idea—the roughly 25 populations she and her colleagues have studied throughout southeastern Colorado really act as two to three genetically, because the hawkmoths do such a great job moving pollen over long distances.

Making Sense of Scent
How do the hawkmoths use floral scent to decide which flower to visit? According to Skogen, they detect scent at a distance in the air with their antennae as they fly. (Once they get closer, flower color and size become more important in locating individual flowers.)

Skogen and her colleagues have determined that flowers in some populations smell very different from each other, and these differences in fragrance can be detected by humans. Fragrance combinations include green apple, coconut, jasmine, and even Froot Loops™.

Skogen’s theories suggest that differences in floral scent may direct female white-lined sphinx moths to the best host plants for their eggs, attract enemies (including seed-eating moths), reflect differences in soil, or the floral fragrance of other plant species flowering nearby.

The white-lined sphinx moth drinks nectar from Harrington’s evening primrose in Colorado.
The white-lined sphinx moth drinks nectar from Harrington’s evening primrose in Colorado.

Fielding Questions
What combinations of genes create the scents that best attract the hawkmoths? What do the genetic data of existing plants tell us about the direction genes have moved in the past? Are other insects, such as herbivores and seed predators, helping to move pollen or inhibiting reproduction?

These are the questions Skogen and her research team, including the Garden’s Jeremie Fant, Ph.D., and students Wes Glisson and Matt Rhodes, will investigate further. Late this summer and in future fieldwork, they will monitor the pollinators and collect floral and plant-tissue samples. 

Back in the Harris Family Foundation Plant Genetics Laboratory and the Reproductive Biology Laboratory at the Garden, they will compare the genetic data of these plants with the observed patterns of the pollinators, and other floral data. 

Each trip is another step closer to having a positive impact on the future of the state-imperiled evening primrose and its choice pollinators. This species is endemic, growing only in southeastern Colorado and northern New Mexico where the unique soils best suit its needs.

Learn more about Dr. Skogen’s work and watch a video.

Because the species grows in limited locations and is easily thwarted by the impacts of development, climate change, invasive weed species, and other intensifying threats, it’s especially important that its future generations are strong.

Skogen’s love for nature has been lifelong. As a child in Fargo, North Dakota, she enjoyed playing in unplowed prairies. Now, at the Garden, she visits Dixon Prairie as often as she can. “There is beauty in the natural distribution of species,” she said. “The prairie habitat is imprinted on me from those childhood experiences. It feels like home.”

©2013 Chicago Botanic Garden and