Archives For Boyce Tankersley

Fragrance is one of the benefits of a garden that is often overlooked.

Lots of thought is given to plants’ textures, colors, seasonality, sizes—all important visual characteristics without a doubt—but a garden with scents provides a deeper, richer experience by supplementing visual stimuli with olfactory. 

Fragrances, like music, often elicit memories, and so this short list of favorite fragrant plants includes a number that I experienced when I was younger. People, places, time—all are recalled with great fondness in a single whiff. 

Also among the list are a number of annuals that are perfect for containers, which allow the gardener to move plants into prominence as they reach their peak throughout the season.

Finally, I believe every garden should have a least one rose; and that it should be fragrant. Rosa ‘Mister Lincoln’, with deep velvety red petals and incredible tea rose fragrance, has stood the test of time. Both Honey Perfume™ (Rosa ‘JACarque’) and Rosa ‘Apricot Nectar’ reflect the current desire to combine fragrance with beauty and disease resistance in a hardy shrub rose. The Chicago Peace rose (Rosa ‘Chicago Peace’) earned a place at the top of our list long before we moved to Chicago with its creamy yellow flowers tinged with pink along the edges of the petals and a delicate rose fragrance. My wife would be upset if I didn’t mention her favorite, a David Austin shrub rose by the name of Evelyn (Rosa ‘AUSsaucer’), which bears delicate apricot-to-pink single-to-double quartered flowers—and a wonderful fragrance.

Rosa 'Mister Lincoln'

Rosa ‘Mister Lincoln’

Honey Perfume rose (Rosa 'JACarque')

Honey Perfume™ rose (Rosa ‘JACarque’)

Evelyn rose (Rosa 'AUSsaucer')

Evelyn rose (Rosa ‘AUSsaucer’)
Photo by Patrick Nouhailler [CC 2.0].

And now, the list:

Honeysuckles are among the most fragrant of garden plants available, but many of the most common are non-native and have begun to “jump the fence” and invade natural areas. Many of the sterile cultivars, unfortunately, are not fragrant, and the species native to the southeastern United States are not reliably hardy (Lonicera sempervirens). Fortunately Lonicera flava—also native to this region—is fragrant. Its yellow-to-orange summer blooms are followed by showy (but inedible) berries in fall.

Lonicera flava honeysuckle is a fragrant and hardy variety.

Lonicera flava honeysuckle is a fragrant and hardy variety. Photo via southeasternflora.com.

Tuberose, Polianthes tuberosa, is a nonhardy (for us) bulb from northern Mexico with an intoxicating scent so distinctive it is known simply as “tuberose.” Creamy white flowers on spikes appear from late summer up to frost. Like many fragrant plants, the scent was developed to attract night-flying pollinators and becomes more intense as late afternoon transitions to evening. Tuberose is great in a large container or can be planted in flower beds.

Hosta have long been used by gardeners to fill parts of the garden that are heavily shaded. While they all flower, ‘Royal Standard’ (among others), produces large, white intensely fragrant (in the evening) flowers in late summer.

Oncidium Sharry Baby 'Sweet Fragrance'

Oncidium Sharry Baby ‘Sweet Fragrance’

One of the featured plants from the Garden’s recent Orchid Show, Oncidium Sharry Baby ‘Sweet Fragrance’ is easily grown on a brightly lit windowsill in the home. A relatively small plant maturing at about 6 inches in height, it produces sprays of pinkish red, sweetly fragrant flowers almost year-round. It’s not overpowering.

At the end of the daffodil season, end of May to the beginning of June, a small-statured Narcissus jonquilla fills the garden with delightfully sweet scents. Relatively small in stature, the bright yellow flowers, one to three per stem, are produced above grass-like foliage. Unlike some of the larger leafed cultivars, there is rarely a need to fuss with the foliage as it dies back. Tuck it in among perennials and small shrubs.

Garden stock (Matthiola incana) is another one of those plant groups that for a while, featured size, shape, and color of the flowers at the expense of fragrance. Fortunately the pendulum has swung back and a number of modern cultivars feature fragrance in addition to some really cool colors.

Prairifire crabapple (Malus 'Prairifire')

Prairifire crabapple (Malus ‘Prairifire’)

Crabapples bloom here at the Garden, reliably on Mother’s Day, and their fragrance is another one so distinctive as to be given its own name. Malus ‘Prairifire’ is not only fragrant, but is smaller in size—perfectly suited for modern gardens. It features white to pink flowers and showy red fruit in fall.

Paeonia 'Festiva Maxima'

Paeonia ‘Festiva Maxima’

The herbaceous peony Festiva Maxima is an old cultivar but its fragrance has earned it a spot in the moving van during every move. White flowers flecked with red have that wonderful peony fragrance. It needs staking and if planted in a crowded location, is susceptible to powdery mildew. Recipes online provide instructions on using the petals to make peony-scented jelly—a very delicate, flavored sweet with a light pink color. Small nectar glands on the sides of the flower buds attract small ants to the plants. The ants don’t pollinate the flowers, but they are important to the dispersal of the seeds later in the year. The seeds feature an elaiosome (fleshy appendage) that the ants strip off and feed upon once they have hauled the seed to their nest—insuring the dispersal of peony seeds. The nectar is simply there to make sure they are around when the seeds are ripe.

Phlox paniculata 'David'

Phlox paniculata ‘David’

Many of the garden phlox, Phlox paniculata, feature a vanilla clove fragrance in mid-summer. The cultivar ‘David’ features pure white flowers on disease-resistant foliage. I let it reseed in the garden, and the results are spectacular—the offspring feature light to dark lavender flowers surrounding the white parent.

Nicotiana alata 'Perfume Deep Purple'

Nicotiana alata ‘Perfume Deep Purple’

Fragrant tobacco, Nicotiana alata, produces tall spikes of sweetly scented long, tubular white flowers throughout the summer. I let mine reseed underneath the dryer vent, ensuring a return the following year. This plant is great in containers or used as an in-ground annual.

Clove currant (Ribes odoratum) is an underutilized medium-sized shrub with bright yellow flowers with, you guessed it, the scent of cloves. This is a great plant as a mounded specimen or can be utilized as a hedge.

Butterfly bushes are another of the “must have” sweetly scented garden plants. Like others on this list, the cultivars I grew up with have developed a bad habit of “jumping the fence” and invading natural areas. Plant breeders have risen to the challenge and produced a number of sterile hybrids. Lo & Behold Blue Chip is smaller in stature with lavender-to-blue flowers with the classic fragrance. Asian Moon is a larger growing cultivar with deep purple petals surrounding the orange throat and a rich, sweet fragrance.

Pineapple sage, Salvia elegans, is a classic selection for a “brush against” plant for a location near a walkway or door. Dill, parsley, basil, thyme, rosemary, scented geraniums, and many other herbs can be selected to add their notes to the garden, depending on the gardener’s tastes.

Heliotrope arborescens

Heliotropium arborescens

Heliotrope, Heliotropium arborescens, rounds out the favorites list. Deep purple flower clusters add a wonderfully sweet scent to the landscape and work out well in containers or in-ground locations.


©2017 Chicago Botanic Garden and my.chicagobotanic.org

This past summer, the Chicago Botanic Garden joined an intrepid team of plant collectors from four other American institutions on an expedition to the Republic of Georgia.

Our focus: to collect seeds to diversify the genetic diversity of ex-situ plant collections; to bring back and evaluate species for their ornamental potential; and to provide a hedge against natural and man-made disasters—all while building upon institutional collaborations developed during previous expeditions.

The PCC16-Georgia group poses at the Old Omalo Guest House in the Tusheti Region, Georgia.

The PCC16-Georgia group poses at the Old Omalo Guest House in the Tusheti Region, Georgia. From left to right: Joe Meny (US National Arboretum), Peter Zale (Longwood Gardens), Boyce Tankersley (Chicago Botanic Garden), Vince Marrocco (Morris Arboretum), Koba (owner of Old Omalo Guest House/Hotel Tusheti), Matt Lobdell (The Morton Arboretum), Temuri Siukaev (driver), Koba’s daughter, Constantine Zagareishvili (driver), Manana Khutsishvili (botanist), David Chelidze (botanist)

Map showing the location of the Republic of Georgia.

Just east of the Black Sea is the Republic of Georgia. Map courtesy worldatlas.

The Republic of Georgia was chosen because it is the only biodiversity hotspot that is situated within the temperate climatic zones.

Over millennia, the high peaks of the Greater Caucasus Mountains to the north, Lesser Caucasus Mountains to the south, and their inter-connecting mountain ranges situated between the Black Sea to the west and Caspian Sea to the east have provided a refuge for species that have gone extinct elsewhere due to glaciation and other climate extremes.

Tucked into hundreds of microclimates created by this varied topography, many of these endemic species (found nowhere else on earth) are perfectly hardy in American, Russian, and European gardens much farther north. 

Coordinating the trip on the Georgian side were our colleagues from the Institute of Botany, Tbilisi and Bakuriani Alpine Botanical Garden. They provided invaluable logistical support through the use of two of the foremost botanists in the region, drivers, vehicles, and places to stay.

The varied topography of the Tusheti Region.

The varied topography of the Tusheti Region.

Bakuriani Alpine Botanical Garden, Institute of Botany, and American collectors at Bakuriani Field Station.

Bakuriani Alpine Botanical Garden, Institute of Botany, and American collectors at Bakuriani Field Station

In a little more than two weeks in the field, the group traveled more than 1,100 miles from the high—and barely accessible—Greater Caucasus Mountains of the Tusheti region in northeastern Georgia, through the central valleys, to Lake Tabatskuri in the Lesser Caucasus Mountains in the south, between the Tetrobi Reserve and Bakuriani Alpine Botanical Garden.

The central valley separating the Greater and Lesser Caucasus mountain ranges.

The central valley separating the Greater and Lesser Caucasus mountain ranges

Lake Tabatskuri is situated between the Tetrobi Reserve and Bakuriani Alpine Botanical Garden; the Lesser Caucasus mountain peaks are in the distance.

Lake Tabatskuri is situated between the Tetrobi Reserve and Bakuriani Alpine Botanical Garden; the Lesser Caucasus mountain peaks are in the distance.

The geographic location of Georgia (Russia to the north, Central Asia to the east, Persia to the south and Asia Minor, the Middle East, and Europe to the west) has made this region a favorite transit point for merchants. Tucked into remote mountain valleys are small communities created from the descendants of Greeks, Germans, Hebrews, Persians, Armenians, Turks, Russians, Circassians, Huns, Mongols, and more, with remnants of each people’s own unique culinary, religious and linguistic traditions.

It was also, unfortunately, a thoroughfare for invading armies. Ancient fortifications, places of worship, homes—all show evidence of destruction and rebuilding.  

Samshvilde Fortress ruins.

Samshvilde Fortress ruins

Fortified towers are a typical feature of many homes in the Greater Caucasus mountains.

Fortified towers are a typical feature of many homes in the Greater Caucasus mountains.

Church of St. George.

Church of St. George

The collections wrapped up with a foray into western Georgia (ancient Colchis in Greek mythology) in and around Kutaisi, the legislative capital and its third largest city. A brief visit to the Kutaisi Botanical Garden was in order here, before we left the region. A highlight: a small shrine built inside a living 450-year-old oak. 

In all, 205 different seed lots and herbarium vouchers—representing 169 different species of trees, shrubs, perennials, and bulbs—were collected, including six of seven species of Quercus (oaks) in support of the IUCN Redlist of all of the Quercus in the world.

Religious shrine built inside a 450-year-old Quercus hartwissiana at Kutaisi Botanical Garden.

A religious shrine is built inside this 450-year-old Quercus hartwissiana at Kutaisi Botanical Garden.

What a haul! Seed collectors admire hundreds of seed collections to be cleaned.

What a haul! Admiring hundreds of seed collections to be cleaned are (left to right): Dr. Fritz, Dr. Tatyana Shulina (Garden consultant), Dr. Manana Khutsishvili (lead Georgian botanist) and Dr. Marina Eristavi (botanist on a former trip).

While we each came away with a fantastic collection of seed to propagate, this trip was about much more than collecting plants. Our journey’s end featured a meeting with representatives of institutions from America, Armenia, Azerbaijan, and Georgia all focused on expanding collaboration to match areas of expertise with areas of need—not only in the area of collections, but also horticulture, conservation science, education, and fundraising/collaborative grants.

The Caucasus Regional Meeting Participants pose on balcony at the of Institute of Botany. The ancient Narikala Fortress of Tbilisi is in the background.

The Caucasus Regional Meeting participants pose on balcony at the of Institute of Botany. The ancient Narikala Fortress of Tbilisi is in the background.

Left to right: Dr. Marine Eristavi, conservation scientist, National Botanical Garden of Georgia, Dr. Tinatin Barblishvili, deputy director, National Botanical Garden of Georgia, Dr. Lamara Aieshvili, curator of rare and endemic plants of Georgia ex situ collection, National Botanical Garden of Georgia, Vince Marrocco, horticulture director, Morris Arboretum, Dr. Manana Khutsishvili, botanist, Institute of Botany, Tbilisi, Dr. Peter Zale, curator and plant breeder at Longwood Gardens, Matt Lobdell curator of The Morton Arboretum, Dr. Fritz, Dr. Tatyana Shulkina, former curator of the living collections of the Soviet Union, Komarov Botanical Garden and currently Chicago Botanic Garden consultant, Dr. Rashad Selimov, head of education, Institute of Botany Azerbaijan Academy of Sciences, Baku, Joe Meny from the US National Arboretum, Dr. Vahid Farzaliyev, National Botanical Garden Azerbaijan Academy of Sciences, Baku, Boyce Tankersley director of living plant documentation at the Chicago Botanic Garden, Dr. Shalva Sikharulidze, director of Institute of Botany, Georgia and Bakuriani Alpine Botanical Garden, Dr. George Fayvush, Department of Geo-botany Armenian Academy of Sciences, Yerevan, Dr. Zhirayr Vardanyan director of the Institute of Botany and National Botanical Garden Armenian Academy of Sciences Yerevan

What can we expect from our efforts? New blooms in the Garden! We have added quite a few plants to those brought back from Georgia on three previous trips:

Lilium monadelphum

Lilium monadelphum

Muscari armeniacum

Muscari armeniacum

Tulipa undulatifolia

Tulipa undulatifolia

Bellevalia makuensis

Bellevalia makuensis

Campanula lactiflora

Campanula lactiflora

Gentiana schistocalyx

Gentiana schistocalyx

Stachys macrantha

Stachys macrantha

Stokesia major

Stokesia major

Dianthus cretaceous

Dianthus cretaceous

Iris iberica ssp. Elegantissima

Iris iberica ssp. elegantissima

Verbascum pyramidatum

Verbascum pyramidatum

Colchicum trigyna

Colchicum trigyna

Stay tuned! Invitations have been received from institutions in Armenia, Azerbaijan, and Georgia for future plant collecting trips to the region. Likewise, scientists from these countries were invited to collect American native plants to increase the biodiversity of their ex-situ collections.


©2016 Chicago Botanic Garden and my.chicagobotanic.org

Want to help monarch butterflies? Be careful when selecting your milkweed. Not all plants that go by the common name of “milkweed” are the food that these butterflies need. 

Want to save the monarch butterfly? Plant milkweed. Pick up a free milkweed seedling at World Environment Day this Saturday, June 4.

Danaus plexippus (Monarch) egg on the underside of a leaf.

Danaus plexippus (Monarch) egg on the underside of a leaf. Photo by Bfpage [CC BY-SA 4.0], via Wikimedia Commons

Milkweed is both a food source and a host plant on which the monarch butterflies lay their eggs. Monarchs lay their eggs on the underside of the milkweed foliage.

After hatching, the larvae consume the foliage, which is high in cardiac glycosides—a poison that interferes with the heart functioning of vertebrates (animals with a skeleton). Butterflies are insects with an exoskeleton, and so are not affected by the toxin.

Within the Chicago region, the following milkweed species (Asclepias) are native:

  • Asclepias amplexicaulis is native to our prairies and is suitable for planting in sunny perennial flower gardens. The flowers are described as “eraser pink” in color and are fragrant (honey).
  • Asclepias exaltata is native to our woodlands and is suitable for planting in partially shaded gardens. The flowers are white and also fragrant.
  • Asclepias incarnata is native to both prairie and woodlands and can be planted in a variety of garden locations. The flowers are pink and fragrant. Gardeners may also be interested in three cultivars of this species:
    • ‘Cinderella’ has light and medium pink flowers
    • ‘Ice Ballet’ has white flowers
    • ‘Soulmate’ has medium and dark pink flowers
  • Asclepias tuberosa goes by the common name of Butterfly Weed. It features bright gold and orange flowers—and is fragrant. A native of sunny prairies, it also has cultivars that have been selected for specific colors:
    • ‘Hello Yellow’
    • ‘Western Gold Mix’
    • ‘Gay Butterflies’ (orange, red, yellow)
  • Asclepias purpurascens has fragrant pinkish-purple flowers and can tolerate both sun and shade locations in the home landscape.

Cultivars may be easier to find in your local garden center or nursery, but specialist nurseries do carry both potted plants as well as seeds.

Asclepias syriaca

Asclepias syriaca

Asclepias tuberosa

Asclepias tuberosa

Download the Chicago Botanic Garden Milkweed Map and take a tour of our native milkweeds.

The Bad Seeds

The bad actors, unfortunately, also go by the common name of milkweed, and are in the same plant family but a different genus: Cynanchum. Three species are reported in the upper Midwest and should not be planted by gardeners. All have fragrant flowers and wind-dispersed seeds:

  • Cynanchum louiseae goes by the name of Louise’s swallow wort, or milkweed. It is native to southeastern Europe.
  • Cynanchum louiseae goes by the name of European swallow wort or milkweed. It is native to southern Europe.
  • Cynanchum vincetoxicum goes by the name of white swallow wort or milkweed. It is native to Europe and Asia.

So, why will monarch larvae die on the wrong milkweed? 

Hmmm, perhaps an illustration. Both mango and poison ivy are in the same plant family (Anacardiaceae) and contain similar biologically active compounds. My daughter and I can’t get enough mango in our diet, but both break out in poison ivy rashes if we touch poison ivy plants. The compounds are similar but not exactly the same.

Likewise with the “bad” and “good” milkweeds: Both have fragrant flowers, the flower shapes are similar, the leaf shapes are similar, both have milky sap. But there is an insecticide compound in the “bad” milkweed in addition to the cardiac glycoside.

“Bad” milkweeds evolved in Europe, where there are no native monarch butterflies, but plenty of herbivores, both animal and insect. “Good” milkweeds evolved in North America in conjunction with monarch butterflies.

Monarch caterpillar

Monarch caterpillar

Somehow, the monarch larvae are able to ingest and retain cardiac glycosides in their tissues without dying. It is a very unique adaptation between these two species. If other species of butterflies were to lay their eggs on milkweed, the larvae would not survive. Each organism has these sorts of “monarch-like” relationships with other, sometimes drastically different organisms that give them a survival advantage. Monarchs just happen to be a wonderful example of mutualistic relationships.

Learn more:

The Monarch Joint Venture lists a number of national and regional partners; each of them will have information about monarch butterflies. The U.S. Fish and Wildlife Service, which is partnering with the National Wildlife Federation and National Fish and Wildlife Foundation, is also a source for information on milkweed and monarchs. Get free milkweed plants at monarchwatch.org.

Million Pollinator Garden Challenge

Add your garden to the Million Pollinator Gardens project this summer. Learn more at millionpollinatorgardens.org.


©2016 Chicago Botanic Garden and my.chicagobotanic.org

The Critical Search for a Plant

Chicago Botanic Garden provides rare plant for toxin testing

Boyce Tankersley —  November 13, 2015 — 5 Comments

The clock was ticking—a little girl was seriously ill—when I got the call for help. A Denver hospital needed living tissue from Thujopsis dolabrata or any of its cultivars within 24 hours to determine if the plant was the cause of the girl’s life-threatening allergic reaction.

Don’t call us first! Call the U.S. Poison Control Center at (800) 222-1222. If you need help identifying a plant to determine if it’s poisonous—and it’s not an emergency—try our Plant Information Service at (847) 835-0972. Please bring in a live plant sample for an accurate identification.

The girl had been flown in from Japan to be treated at the hospital, National Jewish Health. After I got the call, I looked into the hospital, which is known worldwide for treating patients with respiratory, immune, and related disorders. In the girl’s case, the doctors apparently had a list of potential allergens they were testing, including Thujopsis, a rare evergreen shrub that is native to Japan.

A hospital official began the search for the plant with a colleague of mine at the Denver Botanic Gardens. My colleague met the girl’s grandmother, who showed her a picture of the patient’s red and inflamed face. When my colleague couldn’t help, she checked around and found via the Chicago Botanic Garden’s free smartphone app, GardenGuide, that we have the plant, commonly known as hiba arborvitae.

While the call came out of the blue—in my 17 years at the Garden, I’ve never fielded such a request—this type of emergency was not new to me. I used to be in charge of landscaping at the University of Texas Medical Branch in Galveston, and occasionally supplied plant samples from the campus gardens to the Texas Poison Control Center. Now, as the Garden’s director of living plant documentation, the response just kicked in.

It’s always a good idea to be aware of toxins in your home. The ASPCA keeps a list of houseplants that are toxic to pets; for a list of commonly available houseplants toxic to humans, check out this most common poisonous houseplants fact sheet from the New York Botanical Garden.

PHOTO: Thujopsis dolabrata 'Variegata'.

Thujopsis dolabrata ‘Variegata’

In the Garden’s production nursery, I snipped a branch from two different cultivars of Thujopsis. Within three hours of receiving the request, I had dropped the samples off at FedEx on the way home.

As it turned out, Thujopsis did appear to be the culprit, and the hospital is continuing to test the girl’s blood samples with extracts from the Thujopsis to determine what constituents are causing the allergic reaction (the same constituents can be found in related species, so the search to identify other potential sources is prudent). Meanwhile, the girl responded quickly to emergency treatment, was stabilized, and returned to Japan.

While public gardens and other outdoor spaces are often recognized for their mental health benefits, this incident reminded me of the fact that botanic gardens have made important contributions to the physical well-being of people in need.

For more than 450 years, botanic gardens have collected and housed plants from throughout the world for the public good, from medicinal plants in the sixteenth century to food crops used to expand and improve people’s diets (like potatoes, tomatoes, and corn introduced to Europe from the New World, and global economic plants like tea and cocoa). I’m proud to be a part of this history. 


©2015 Chicago Botanic Garden and my.chicagobotanic.org

Each fall, we sing the praises of fall allium and autumn crocus blooms. This year, however, a special mention must be made for the glorious gladiolus! Especially the delicate, 4-inch salmon pink flowers of the salmon gladiolus (Gladiolus oppositiflorus spp. salmoneus).

Hailing from the summer rainfall areas of the cold, higher elevations of the Drakensberg Mountains of South Africa, this beautiful wild species has proven amazingly hardy in the Chicago Botanic Garden’s Graham Bulb Garden over the last five years—including a couple of winters with record-setting cold temperatures!

PHOTO: Gladiolus oppositiflorus ssp. salmoneus.

Gladiolus oppositiflorus ssp. salmoneus produces elegant, upright flower stalks that do not require staking!

Two characteristics of its native habitat nominated the gladiolus for trial at the Garden: first, it is a winter-growing bulb in South Africa, which translates to summer growth in North America. Second, this plant thrives in moist soils in grassy areas—it was perfect for the site we chose in the Bulb Garden.

Based upon its initial success in our plant trial program, other gladiolus (also currently in full flower) were added to the trials. We’ve also discovered that these wild species thrive and multiply in well-drained soils (but do not tolerate flooded soils). The beautiful, red-flowered Gladiolus saundersii is also native to the Drakensbergs, but from a higher, colder, and snowier habitat. And a third selection is probably a close relative of Gladiolus dalenii var. primulinus. Discovered in an old, abandoned farmstead in North Carolina, and sold under the name ‘Carolina Primrose’, this gladiolus generally blooms in July and early August (although it is still blooming now). All have come through the record-breaking cold of the last couple of winters. 

Gladiolus is the largest genus in the Iridaceae (iris plant family) with 255 species worldwide; 166 of them in southern Africa. The genus was given its name by Pliny the Elder, in reference to the size and shape of the leaves, which are similar in shape and size to a short sword favored by Roman-era gladiators: the gladius.

It’s not easy to find commercial sources for these bulbs, but it’s well worth the effort to obtain an elegant, refined, fall-flowering, and hardy gladiolus.


©2015 Chicago Botanic Garden and my.chicagobotanic.org