A stunning butterfly from western Africa, the flame-bordered charaxes (Charaxes protoclea) is well-named: it definitely looks aflame in bright sunlight! Seen from above, the lower central portions of the female’s wings are white-hot; the wingtips display a range of yellow-to-orange spots, and a strip of brilliant orange frames each wing. (The males’ wings are a muted brownish-black, but also bordered in fiery orange.)
From below, charaxes are much more toned down, colored in muted browns and grays with a single dark eye spot. Male butterflies are a subtle maroon-brown in color, while females are light tan, with a single wide, white stripe midwing. The different coloring on the wing patterns of each sex is known as sexual dimorphism, and is fairly common in butterflies (see our mocker swallowtail post for another kind of dimorphism).
Before our might, the foliaged foe fell along a stretch of the Green Bay Trail near the Braeside Metra station.
That’s where a group of 50 of us gathered to vanquish thickets of invasive buckthorn (Rhamnus sp.) on Wednesday, June 19. The removal was initiated by the City of Highland Park and the Park District of Highland Park in partnership with the Chicago Botanic Garden. Ravinia Festival also provided volunteers and space for parking and picnicking afterward.
“This was an ideal place to demonstrate what buckthorn control could accomplish through taking back our beautiful natural surroundings, even in very busy settings,” said Rebecca Grill, natural areas manager for the Park District. The area links two major cultural institutions serving the community, the Garden and Ravinia. It is also near a planned bike path for cyclists and pedestrians that eventually will extend to the Garden, connecting the North Branch and Green Bay Trails.
From 9 to 11 a.m. we sawed, chopped, cut, tugged, pulled, dragged, and stacked so much buckthorn that by the time a break was called, some piles were as high as me (5 feet), extending in an impressive line down the trail. Joggers, walkers, and cyclists made their way past the activity, occasionally cheering on the workers, including Garden President and CEO Sophia Siskel and her sons.
Why has buckthorn become such a problem in the Midwest? It’s the story of a plant species imported for perceived benefits that runs amok, crowding out less aggressive native plants and altering the landscape. Buckthorn arrived in the United States in the mid-1800s, brought from Europe as an ornamental plant admired for its thick, long-lasting foliage and fast growth. Native birds relished the fruits of the tall shrub and helped to disperse them. Once scattered, the seeds could remain dormant for as long as six years. In contrast to native plants, buckthorn supports almost no native invertebrates, like butterflies and moths, many of which are either food for native animals or serve as important pollinators. Soon buckthorn expanded far beyond its original boundaries of home landscapes and farms—where it was used as a windscreen—crowding out native plants, changing nutrients in the soil, and threatening native habitats.
How much buckthorn did we eliminate? Rebecca estimated that our group cleared 1,500 feet of trail—more than a quarter-mile. At 2:30 p.m., she and her crew were still feeding the cut plants into a wood chipper, making sure the chances of reseeding are minimal. They also selectively applied herbicide to the remaining stumps. In the future, they plan to monitor the area for the return of native wildflowers, seeding if necessary.
I live near the trail and run along it often. Already I have enjoyed seeing how the sunlight filters into this new clearing, reaching areas that will soon flourish with returning “natives.”
Learn more about invasive species on the Garden’s website. For information about future buckthorn workdays, contact Liz Ettelson at the Park District of Highland Park (firstname.lastname@example.org).
Our “founding gardeners”— author Andrea Wulf’s depiction of early U.S. presidents who passionately promoted farming as a means to independence — would be tickled to see the American Seed Saver bed in the Regenstein Fruit & Vegetable Garden. There, visitors will find varieties of heirloom fruits and vegetables grown by our third president, Thomas Jefferson, in his country estate at Monticello, just outside Charlottesville, Virginia. Many of these varieties are also grown in Michelle Obama’s organic vegetable garden on the White House grounds.
The American Seed Saver bed also honors everyday gardeners who help safeguard the genetic diversity of plants, according to Garden horticulturist Lisa Hilgenberg, who oversees the Fruit & Vegetable Garden. “Because of the work of home gardeners and seed-saving organizations, an increasing number of heirloom varieties are now available to the public,” she said.
Heirloom vegetable varieties are open-pollinated plants that reproduce themselves, staying “true to their parents,” according to Hilgenberg. They’ve been handed down through generations, a practice that helps maintain the food crop gene pool for future generations.
The Abraham Lincoln tomato (Solanum lycopersicum ‘Abraham Lincoln’) was planted in our American Seed Saver bed as a tribute to our 16th president, who established the United States Department of Agriculture more than 150 years ago. The big, sweet, and juicy tomato is a good slicer and also makes great ketchup. “What could be more American than that?” Hilgenberg said. “Other cultures dry their tomatoes or make paste. We’re going to put them on our burgers.”
Visitors to the American Seed Saver bed can also see the rattlesnake bean (Phaseolus vulgaris), said to originate from the Cherokee people. The variety is also known as the preacher bean because its abundant yield of purple-streaked green pods gives cause for thanks and praise. The nearby Painted Lady bean (Phaseolus vulgaris ‘Painted Lady’), native to Mexico, was popular in England by the 1850s and a favorite in America by the early 1880s.
The sweet and spicy Alma Paprika pepper (Capsicum annuum ‘Alma Paprika’), of Hungarian origin, can be dried and ground into paprika and is cited in one of the earliest American cookbooks, according to Hilgenberg. In the American Seed Saver bed, the plant also serves as a symbol of America as a melting pot of cultures and traditions. “We’re such a nation of immigrants and now we have gardens with plants from all over the world,” Hilgenberg said. “We’ve made them our own.”
I am happy to report that we now have white morphos (Morpho polyphemus) in the Butterflies & Blooms exhibit! This ghostly beauty is native to Mexico and Central America including Costa Rica, like its relative the common morpho (Morpho peleides).
The white morpho gets its scientific name from the small eyespots on its wings. Polyphemus, a character in Greek mythology, was the one-eyed son of Poseidon and Thoosa.
Our white morphos can be spotted drinking rotten fruit, which they prefer over plant nectar. This extremely beautiful, iridescent butterfly is not to be missed. She is truly stunning and worth coming out to see!
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.
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.
“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.
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.
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.
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.
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.”