Archives For What’s in Bloom

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Autumn Asters

Jacob Burns —  September 26, 2017 — 1 Comment

The harbinger of fall, for many folks, is when asters finally bloom. Their flowers look like miniature daisies and come in shades of purple, blue, white, and occasionally pink. These cool tones allow autumnal hues of yellow, orange, and red to truly pop throughout the landscape. Aster blossoms twinkle across roadsides, meadows, woodland edges, and even home gardens. Interestingly, astéri is the Greek word for star.

White wood aster (Eurybia divaricata)

White wood aster among birch trunks near the Bernice E. Lavin Plant Evaluation Garden sets the perfect fall scene.

Hosts of pollinators favor asters. The late-season blooms provide vital sustenance for adult monarch butterflies during their annual migration to Mexico. Each flower contains plentiful sources of pollen and nectar, because the central disc is comprised of up to 300 tiny florets. After pollination, a disc will turn darker and reddish, informing other insects to keep moving. In the end, birds come to consume the seeds.

Asters belong to a huge family called Asteraceae, which also includes daisies, black-eyed Susans, and sunflowers. They are mainly native to North America and Eurasia. More than 600 species once made up the genus known as Aster. However, in the 1990s, taxonomists decided to divide New World species into ten other genera. The most common ones are Eurybia and Symphyotrichum. Few nurseries adopt these names and continue to list their plants under the genus Aster

Asters are easy to please with well-drained soil and adequate sunlight. Some even prefer shade. An assortment of heights (1 – 6 feet tall) allows them to shine in the front, middle, or back of the border. Powdery mildew is problematic for some, but you can always hide the unsightly lower stems among grasses or ferns. While pretty in nature, some asters just look scruffy in the garden. Selecting the right type is the key to a tidy look. The following asters perform best:

Jindai Tatarian aster (Aster tataricus 'Jindai')

Jindai Tatarian aster (Aster tataricus ‘Jindai’) can be found in the Lakeside Garden and on Evening Island at the Trellis Bridge.

White wood aster (Eurybia divaricata)

White wood aster (Eurybia divaricata) can be found in the Heritage Garden beds, throughout the Landscape and Bulb Gardens, in large groupings on Evening Island, and all around the Plant Science Center.

Jindai Tatarian aster (Aster tataricus ‘Jindai’) originates in Asia and has uniquely large and toothed foliage. From mid- to late fall, lavender-blue daisies appear in showy flat-topped clusters upon 3 – 4 foot tall stems. Best planted in the back of a bed with plenty of sun and space, its roots slowly spread into a weed smothering ground cover. Pair it with some equally tall and tough switchgrass (Panicum virgatum).

White wood aster (Eurybia divaricata) blooms for a long time, starting in late summer and lasting throughout fall. Clouds of starry white flowers are borne on 2-foot stems with heart-shaped leaves. It grows in woodlands of eastern North America where it spreads slowly by rhizomes and quickly from seed. Cut spent flower stems off if you do not want extra plants. Combines wonderfully with ferns, sedges, and shade-loving goldenrods like Solidago caesia or Solidago flexicaulis.

Avondale blue wood aster (Symphyotrichum cordifolium 'Avondale')

Avondale blue wood aster (Symphyotrichum cordifolium ‘Avondale’) can be found on Evening Island, just west of the carillon along the path.

October Skies aromatic aster (Symphyotrichum oblongifolium 'October Skies')

Find aromatic aster (Symphyotrichum oblongifolium ‘October Skies’) in the Landscape Garden, along the Lakeside Garden path, at McGinley Pavilion, on Evening Island near the Arch Bridge, and near the Plant Science Center.

Avondale blue wood aster (Symphyotrichum cordifolium ‘Avondale’) is an extra-floriferous selection of an eastern North American species found at forest edges. A plethora of attractive blue flowers begin in early fall on 2 – 3 foot stems. Grows well in either sun or shade, where it adds additional color to perennials like Japanese anemone (Anemone hupehensis), monkshood (Aconitum), and the yellow fall foliage of blue star (Amsonia hubrichtii).

October Skies aromatic aster (Symphyotrichum oblongifolium ‘October Skies’) is a great alternative to New England aster (S. novae-angliae), because it is less prone to powdery mildew. With full sun, it forms a compact 2- x 2-foot mound of nicely scented foliage. In autumn, hundreds of blue-purple flowers cover the plant. The species naturally occurs across the central and eastern United States. Try it with fountain grass (Pennisetum alopecuroides).

Frost aster (Symphyotrichum pilosum)

Frost aster (Symphyotrichum pilosum) overflows the center plantings of the Heritage Garden.

Frost aster, or hairy aster (Symphyotrichum pilosum) is a 3- x 3-foot, clump-forming plant with many branched and arching stems. In fall, it becomes loaded with little white daisies and creates a baby’s breath appearance among flowers like Japanese anemone (Anemone hupehensis). Frost aster is common in a variety of dry, sunny habitats in eastern North America. It spreads happily by seed, so if you have too many, cut off the spent flower stems before they develop any further.


©2017 Chicago Botanic Garden and my.chicagobotanic.org

The fourth of July is upon us, and while many beautiful flowers can be found in patriotic shades of red and white, the color blue is very difficult to find at the Garden.

In fact, blue is a rare sight in the entire natural world. Less than ten percent of the plant kingdom features blue flowers, which is extraordinary, since pollinators don’t seem to have a problem with them. Scientists have been investigating the origins of blue flowers for a long time, and it was not until recently that they came up with a result.

Blue sea holly (Eryngium planum)

Blue sea holly (Eryngium planum)

Flower colors are based on pigments that include anthoxanthins and anthocyanins. Anthoxanthin colors contribute to yellow flower petals and are quite common in the plant world. Anthocyanin colors impart red, purple, and blue in blooms, but are found much less often in flora. For anthocyanin to steer blue, complex scenarios must occur. Most often, metal atoms and ions interact with the pigment to modify the color. In addition, they alter the pH of cellular fluids to be alkaline, while most organisms have an acid or neutral chemistry.

What is thought-provoking is that a red rose and a blue cornflower (Centurea cyanus) contain the same anthocyanin pigments. Cardinal flower (Lobelia cardinalis) and big blue lobelia (Lobelia siphilitica) are of the same genus, but one flower is red and the other is blue. It is the rare and complex modification of that pigment that contributes to the blue flower being blue. More surprising is that hybridizers have yet to develop a truly blue rose or carnation (without resorting to pigmenting water, which a plant takes up, changing the color of its bloom). 

Royal Aspirations larkspur (Delphinium elatum 'Royal Aspirations')

Royal aspirations larkspur (Delphinium elatum ‘Royal Aspirations’)

Lobelia (Lobelia erinus)

Lobelia (Lobelia erinus)

Pacific Giant Cameliard larkspur (Delphinium 'Cameliard')

Pacific Giant™ cameliard larkspur (Delphinium ‘Cameliard’)

Since blue is uncommon, visitors at the Garden should take extra time to enjoy the flowers in the English Walled Garden, where they will find containers full of adorable Felicia daisy (Felicia heterophylla ‘Forever Blue’) right beside sky-colored plants called southern star (Tweedia caerulea ‘Heaven Born’)—a member of the milkweed family. In addition, there are cool-hued drifts of Magadi™ electric blue lobelia (Lobelia erinus ‘KLELE10670’) weaving throughout several garden beds, as well as spilling out of containers.

Another area with a good deal of blue flowers is the Heritage Garden. In the plant family area, you will find intricate love-in-a-mist (Nigella damascena ‘Miss Jekyll’) blossoms mingling with wispy yet showy Siberian larkspur (Delphinium grandiflorum ‘Blue Butterfly’). And nearby, nile lily flowers (Agapanthus ‘Queen Anne’) explode like bright blue fireworks. And finally, in the geographic area, sea holly (Eryngium planum) creates a shiny and spiky blue accent.

(Agapanthus africanus 'Queen Anne')

Nile or African lily (Agapanthus africanus ‘Queen Anne’)

Love-in-a-Mist (Nigella damascena 'Miss Jekyll')

Love-in-a-mist (Nigella damascena ‘Miss Jekyll’)

Blue Butterfly larkspur (Delphinium grandiflorum 'Blue Butterfly')

Blue Butterfly larkspur (Delphinium grandiflorum ‘Blue Butterfly’)

While it is difficult to achieve blue pigments in plants, the ones that did are certainly successful in this world. The word “perseverance” comes to mind, which just so happens to be what the blue within the American flag represents. Anyone who has marveled at a field of Texas bluebonnets (Lupinus texensis) and witnessed the huge number of bees and butterflies working to gather its pollen would agree.

Southern star (Tweedia caerulea 'Heaven Born')

Southern star (Tweedia caerulea ‘Heaven Born’)

Flying Saucers morning glory (Ipomoea tricolor 'Flying Saucers')

Flying saucers morning glory (Ipomoea tricolor ‘Flying Saucers’)

Happy Fourth of July everyone!


©2017 Chicago Botanic Garden and my.chicagobotanic.org

Wolfsbane is a beautiful—and poisonous—fall-blooming perennial. It also has a colorful history associated with werewolves, vampires, and witches.

PHOTO: Werewolf gargoyle at the Cathédrale Notre-Dame de Moulins

Werewolf gargoyle at the Cathédrale Notre-Dame de Moulins

The plant has been a familiar plot element in horror movies, television shows, and novels. In the Harry Potter series, Remus Lupin, a tormented werewolf, drinks a potion of wolfsbane carefully concocted to control his transformations. As early as Dracula in 1931, wolfsbane casually replaced garlic as a repellent for vampires in film. Nevertheless, the correlation of wolfsbane with the supernatural predates Hollywood and familiar authors. 

In Greek myth, wolfsbane (Aconitum) originated from the toxic slobber of a three-headed dog named Cerberus, the scary canine guardian to the gates of Hell. In the Dark Ages, wolfsbane was said to be used by witches in spells and potions and was one of several ingredients for an ointment that, when applied to a broom, could facilitate flight. Stories also proclaimed that a sorceress who carried wolfsbane seeds wrapped in lizard skin could become invisible and witches who applied the poisonous sap to their flints and launched them at unsuspecting enemies.

One thing both Hollywood and horticulturists can agree on: wolfsbane is a potent plant. Ingesting wolfsbane is typically fatal. 

PHOTO: Arends azure monkshood/wolfsbane.

Arends azure monkshood (Aconitum carmichaelii ‘Arendsii’)

PHOTO: Lamarck monkshood/wolfsbane.

Lamarck monkshood (Aconitum lamarckii)

The plant belongs to a genus of highly poisonous perennials known as monkshood or aconite. They naturally grow in mountainous areas across the northern half of the globe and are also planted in gardens for their deep purple blooms, which continue flowering long after other perennials fade for the season. Ancient Greeks hunted wolves by poisoning their bait with this plant, which lead to the common name of wolfsbane.

PHOTO: Werewolf illustration circa 1512 by Lucas Cranach the Elder

Werewolf illustration circa 1512 by Lucas Cranach the Elder

While those hunting traditions were lost, the plant retained its common name into the Middle Ages, where wolves and werewolves were a genuine fear in Europe. Frightened folks turned to growing wolfsbane for their protection, as superstitions said that werewolves could be repelled by the plant, or even tamed by it. Others, however, believed that having contact with wolfsbane on a full moon could actually cause shape-shifting. Patients who suffered from lycanthropy (the delusion of being a wolf) were prescribed regular—and often lethal—doses of wolfsbane by their medieval doctors.

For gardeners, it is important to remember to always wear gloves while handling a deadly plant such as wolfsbane.

Find wolfsbane at the Garden with our Plantfinder or on the GardenGuide app. Remember to look—don’t touch!—its beautiful blooms. Happy Halloween!


©2016 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

Sure, it snowed just three days into spring—it’s Chicago! This week we’re set to hit the magic temperature, 45 degrees Fahrenheit, and here’s what it will trigger in your garden.

ILLUSTRATION: How trees set buds in spring.


©2015 Chicago Botanic Garden and my.chicagobotanic.org