The Goldenseal Dilemma

In late October 2012 when I was driving down a country road in rural northwest Illinois, I spotted some bright sky-blue asters blooming near the corner of a woodlot. I was traveling between nature preserves in this area of the state collecting seeds for the Dixon National Tallgrass Prairie Seed Bank, so my mind was already tuned in for interesting native flora that might produce a collection for the seed bank. It was impossible to make a positive I.D. traveling at 60 m.p.h., but the color of that patch of blue was intriguing enough to warrant turning around to go back for a closer look.

As I had hoped, the attractive blue flowers belonged to a fine native species called Short’s aster (Symphiotrichum shortii), which inhabits high quality woodlands. This being the case, I thought it prudent to take a peek into the adjoining woodland to see what else might be growing there. To my surprise, within 30 feet of my entry point I stumbled across a large patch of goldenseal (Hydrastis canadensis)—a once common but now rare plant of Illinois woodlands. Its rarity is attributed to its past popularity as a medicinal plant, which led to its overharvest. Along with goldenseal, other quality woodland plants such as bellwort (Uvularia grandiflora) and baneberry (Actaea sp.) were also present.

PHOTO: golden seal (Hydrastis canadensis) in bloom.
This native woodland perennial produces two large, broad, palmately divided leaves atop a 1-foot-tall hairy stem. A small cluster of greenish-white flowers are produced at the base of one of the leaves in spring when the leaves are expanding, and they mature into a cluster of bright red fruits by midsummer. The knotty, bright yellow root of goldenseal has been harvested by humans for centuries for a variety of medicinal uses. Its popularity has led to extreme harvesting pressure culminating in drastically reduced natural populations.

I did not have time to explore the woodland further that day, so I made a note of where it was located and planned on returning to the site soon to explore it further. However, I had one question that I needed to answer before this was to happen: Who owned that woodland? I was confident that it wasn’t a nature preserve, because I had lists and maps of all of the protected preserves in the area. My guess was that it was privately owned. When I left the site, I recalled that there was a home situated just off the road near the middle of the woodland, so I thought that would be a good starting point.

PHOTO: Hydrastis canadensis leaves (with one ripe fruit).
Hydrastis canadensis leaves (with one ripe fruit)

As luck would have it, the owners of the home also owned the entire woodland. I spoke to the owner about the goldenseal I found in the corner of his property and the possibility of making a collection for the seed bank. It turns out that he already knew about the goldenseal population from a conversation that he had had with a local forester years ago. The forester thought that there was a good chance it had been planted there to be harvested for its medicinal value at a later date. This was a likely scenario, considering the size of the population. The owners agreed to allow me to collect its seeds as well as seeds from any other species that I sought for the seed bank. The only problem was that for the seed bank we are primarily interested in preserving the seeds of natural populations, not introduced ones. Seeds from natural populations represent individuals that are ideally suited to that environment by natural selection across generations, and are therefore of more value to those seeking genetically adapted seeds from a particular area.

PHOTO: Hydrastis canadensis fruit.
The raspberry-like fruit of goldenseal is considered inedible, but the roots have many medicinal properties.

So here lies the dilemma: large populations of goldenseal are rare, because of overharvesting. I rarely see this plant in woodlands, and when I do, it is always in small numbers. If this population was cultivated for the medicinal value of its roots, there is a good chance that it does not represent a natural population. I did not collect seeds of goldenseal that fall—the seeds had ripened and dropped much earlier in the summer. Any seed collection for the seed bank could not occur until the following year. This gave me plenty of time to contemplate whether or not to make the collection.

Since my first visit to the woodland, I have made several seed collections of many quality native woodland plants for the seed bank, including a collection of the Short’s aster that led me to the goldenseal discovery. During those collections I have become more familiar with the woods and have discovered additional colonies of goldenseal—some quite distant from the original population. Could these additional colonies represent multiple plantings? Maybe, but the sizes of the additional colonies are quite a bit smaller than the original. Perhaps they represent offspring from the original colony. If that is the case, this may be an indication that this particular woodland is an ideal habitat for goldenseal—even if it is not the original habitat. Or, there is a chance that this is a remnant population that for some reason survived overharvesting forays years ago.

PHOTO: A field of goldenseal in fruit.
A population of goldenseal on the property; one of several colonies where seeds were harvested

I completed a collection of the goldenseal population (estimated at more than 500 plants) for the seed bank on July 24, 2013. A notation in our database notes will read: “Population may not be natural.”


©2013 Chicago Botanic Garden and my.chicagobotanic.org

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.

Mothmatics
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 my.chicagobotanic.org

Is spring as late as we think?

This year, it sure felt like spring was a long time coming — especially compared to last year when it seemed that we went straight into summer! I wonder how the wildflower timing of spring compared to previous years in the Chicago area…

Mayapples, April 25, 2012
Mayapples, April 25, 2012
Mayapples, May 2, 2013
Mayapples, May 2, 2013

For several years now, I’ve been working on a web-based citizen scientist project, called Project BudBurst, with colleagues at the National Ecological Observatory Network (NEON). We study the phenology — the timing of natural events like blooming, fruiting, and leaf fall — of plants around the country. Our participants track when plants bloom in their area, and we compare the reports to records from other parts of the country.

You can help us collect data! Sign up to help at Project BudBurst.

For instance, I’ve been tracking when the first forsythia flower opens on the plants near the Garden’s front gate since 2007. The earliest bloom I have on record in that time was last year, on March 15, 2012. The latest first flower for this specimen was this year, on April 20, 2013. In 2007 and 2008, however, we also had first flowers in mid-April (April 16, 2007, and April 17, 2008, respectively). So, as we look back in time, this year’s bloom time doesn’t feel quite so late. In the graph below we show the variation in flowering dates (using Julian dates, which standardize for differences in dates between nonleap and leap years).

forsythia data

In the Chicago area, we have a wealth of phenology data collected by the authors of our local flora, Plants of the Chicago Region by Swink and Wilhelm (1994). While they were gathering data for their book, they recorded when they saw plants in bloom from the late 1950s to the early 1990s. They record the forsythia bloom period as April 25 to May 5. So, when we look still further back in time, our “late” spring is much earlier than it has been in the past.

I took a similar look at several other species, both native and nonnative, for which we have both Project BudBurst data and data from Swink and Wilhelm’s book. About 70 percent of the species have earlier flowering dates in the last six years compared to those recorded by Swink and Wilhelm. Some of the species that have advanced their flowering dates are in the table below.

Species Earliest First Flower Observations
Common name
Genus species
Swink & Wilhelm
1950s – 1990s
Project BudBurst
2007 – 2012
Days
Advanced
Forsythia
Forsythia x intermedia
April 25 March 15 -40
Spiderwort
Tradescantia ohiensis
May 14 April 12 -32
Dogtooth violet
Erythronium americanum
April 6 March 20 -17
Red Maple
Acer rubrum
March 20 March 6 -14
Mayapple
Podophyllum peltatum
May 1 April 17 -13
Lilac
Syringa vulgaris
May 3 March 20 -44
Black locust
Robinia pseudoacacia
May 9 April 20 -19
Bradford pear
Pyrus calleryana
April 15 April 13 -2

Plant phenology, particularly when plants leaf out and bloom in the spring, is remarkably sensitive to the annual weather. Looking at phenological records over much longer periods of time can tell us a lot about how the climate is changing. Many scientists are comparing contemporary bloom times with historic bloom times recorded by naturalists like Aldo Leopold in the early 1900s, and Henry David Thoreau in the mid 1800s, as well as records kept by farmers, gardeners, and others interested in the natural world. Two of the longest phenological data sets are those maintained for cherry blossoms in Japan (dating back to 900 AD) and for grape harvest dates by winemakers in Switzerland (dating back to 1480 AD).

Plants have so much to tell us, if we take the time to listen!


©2013 Chicago Botanic Garden and my.chicagobotanic.org

The Prairie Patrol

Stranded, a purple coneflower stretches up from an unplowed slice of Minnesota grassland, signaling for help like a shipwrecked sailor on a desert island. Separated from its lifeline — a native prairie filled with plants and pollinators — it illustrates a widespread threat to the entire species.

This specimen arises with a few relatives from a remnant bound by railroad tracks and row crops. It is one of 27 study sites in Douglas County, Minnesota, evaluated each year by Stuart Wagenius, Ph.D., senior scientist at the Chicago Botanic Garden.

Although this plant may survive many more years, he says, it is unlikely to produce offspring due to its isolation. This is serious trouble for a species that relies on a habitat that has already dwindled to 1 percent of its original size. 

Prairie, says Dr. Wagenius, “is one of the most endangered habitats in the world. We want to learn as much about it as we can in part because the opportunity is fading, but also because there are opportunities for us to conserve it.”

Despite having been scraped by a snowplow the prior year, this roadside Echinacea angustifolia plant bore the most heads seen during a long-term study.
Despite having been scraped by a snowplow the prior year, this roadside plant bore the most heads seen during a long-term study.

His research focuses on Echinacea angustifolia, or narrow-leaved purple coneflower, a prominent prairie species native to Minnesota. Begun as his doctoral research project in 1996, it has since become a lifelong mission. He wants to create an improved habitat for existing plants, and increase the species’ ability to reproduce and thrive.  

Each year, he watches the plants on his study sites for damage from a triple-edged sword—pollination, genetic, and ecological issues.

The Pollination Puzzle
When the prairie stretched from horizon to horizon more than 100 years ago, Wagenius explains, a bee could have flown endlessly from flower to flower, carrying and delivering pollen. Are these insects still able to do their job?

Wagenius’s research has shown that the coneflowers continue to receive adequate visits from native bees. In fact, as he gave me a tour of his lab, he showed me an impressive collection of preserved sweat bees—small, emerald-green locals who have not succumbed to the plight of so many bees like the nonnative honey bees.

A native sweat bee collects pollen from a purple-leaved coneflower.
A native sweat bee collects pollen from a purple-leaved coneflower.

Instead, the problem is that the bees can only carry pollen so far. When they have few plants to work with in a small area, the pollen they deliver is not always accepted by the recipients.

The Genetic Glitch
After a few generations, Wagenius explains, all of the coneflowers in a small prairie become related, sharing pollen and some of the same genes. Then, if a bee delivers pollen with the same genes as the recipient plant, the pollen is likely to be rejected. In that case, no new seeds would be produced and no new generation of coneflowers would exist.

“Studying the genetics has offered some pretty good insight into what is going on in these small populations,” he says.

If related pollen is accepted, inbreeding can occur, which often results in weak offspring. Both issues diminish prospects for future generations.

Larger prairies are one potential solution to this problem. The other, Wagenius has found, lies right at his feet.

Wagenius and students discuss the discovery of a fly larva found eating pollen on a plant.
Wagenius and students discuss the discovery of a fly larva found eating pollen on a plant.

The Ecological Equation
In the past, natural fires on the land encouraged plants to flower, leading to new mating opportunities and refreshing local genetic diversity. Development meant the end of most of those fires. So, Wagenius and his team encourage trained land managers to restore fire through controlled burns.

When Wagenius returns to fieldwork this June, he plans to start with a blaze. He will conduct such a burn on a private landscape to increase the number of flowering plants and improve their chances of successful pollination and seed production.

A Family Affair
To begin fieldwork, he will meet on one of the larger study sites with his academic collaborators—including his wife Gretel, who is a botanist, and graduate and undergraduate students. His stay will be long enough that his other family members will join him there.

Researchers count leaves in a plot where 10,000 individual specimens were planted.
Researchers count leaves in a plot where 10,000 individual specimens were planted.

During fieldwork, he and his crew will measure the length and width of the leaves on each plant, and collect seeds that are later counted by Garden volunteers in a laboratory at the Daniel F. and Ada L. Rice Plant Conservation Science Center.

These characteristics help document the fitness of the plants. He will also compare the size of each preserve to the number of incompatible coneflower mates by studying the plants’ genetic patterns.

In addition, Wagenius will meet with local land managers and organizations to share advice on effective techniques. For example, he has suggested a controlled burn rather than plowing and replanting. “I’m glad to promote good conservation practices,” he says.

“I study habitat fragmentation and its consequences,” says Wagenius. Watch a video and learn more about his work.

Fortunately, many people would like to help him save the prairie, from duck hunters to farmers. “I’m in the role of not telling people to do more, but telling them how to do it better,” he explains. “I like being a person in our society helping others to do the right thing.”

This summer, a vision of hope rather than hopelessness will accompany Wagenius as he stands on the prairie with his research team and, well, a few relatives.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

A Rare Plant Portrait: The Silverleaf Sunray (Enceliopsis argophylla)

Project Overview:
Shannon Still and Nick Jensen work on a project studying the impact of climate change on the distribution of rare plants in the western United States. The grant, funded through the Bureau of Land Management (BLM), examines the changes in projected species distributions between now and 2080. The goal of the research is to help BLM to make informed management decisions regarding rare plants. The research takes them to many exciting destinations as they search for rare plants in the west.

 

habit of Enceliopsis argophylla
Habitat of Enceliopsis argophylla, which thrives in gypsum-rich soil.

The silverleaf sunray (Enceliopsis argophylla),  is a photogenic species in the Asteraceae, or sunflower, family. This rare plant grows in basal clumps of silver-colored, hairy leaves with flowers extended on long stalks, and the entire plant may reach 2 feet tall. The flowers nod with maturity.

The large yellow daisy flowers are 3 to 4 inches across when open. They are quite a sight and stand in stark contrast to the habitat. Due to the extreme habitat, silverleaf sunray offers one of the more striking photo opportunities as the plants grow from a barren landscape.

Silverleaf sunray on a barren hillside.
Silverleaf sunray on a barren hillside

Nick Jensen with a silverleaf sunray.
Nick Jensen with a silverleaf sunray

These gems are found in Clark County, Nevada, east of Las Vegas in the Lake Mead area. They are also found in Mohave County, Arizona, close to Lake Mead.

The habitat for the silverleaf sunray has been encroached by Lake Mead and is threatened by off-highway vehicle use to a minor extent. The habitat in which the sunray grows is easily damaged due to the fragile soil environment (see photos to left) in which the species lives. Much like the dwarf bear-poppy (Arctomecon humilis), the silverleaf sunray grows in a gypsum-rich soil that typically has a healthy soil crust. Damage to this crust can allow invasive plants to grow more easily.

The Bureau of Land Management lists the silverleaf sunray as a sensitive species in Nevada and the species was considered, but rejected, for protection under the Endangered Species Act. Around Lake Mead the silverleaf sunray grows with the golden bear-claw poppy or Las Vegas bear-poppy (Arctomecon californica), a federally listed species. So while the species is not federally listed, the habitat is often protected due to the proximity of other federally listed rare plants.

Side view of the silverleaf sunray flower.

Silverleaf sunray is a striking plant that grows in close proximity to urban and recreation areas. If you are ever in the Las Vegas area, it is worth traveling the short distance to see these plants.


©2013 Chicago Botanic Garden and my.chicagobotanic.org