Archives For September 2017

It might be fall, but the last weeks of September felt like summer, and that’s going to change how long trees will show off their seasonal colors.

On the official first day of fall, temperatures in the Chicago area reached well into the 90s. Heat and the recent lack of rainfall means trees are going into survival mode to conserve water, which means that mid-October’s typical fall colors will be affected. 

Deciduous trees, explains Boyce Tankersley, director of living plant documentation, respond to environmental conditions when preparing to go dormant for the winter. Just like animals that hibernate, trees slow their processes down in order to conserve energy. What we can see of this process can be beautiful: leaves change from green to vibrant reds, oranges and yellows. Then trees will drop their leaves and wait out the winter.

In a regular year, trees aren’t in a rush to go dormant. The process that we see takes several weeks. The production of chlorophyll, which produces the green color in leaves, fades away, unmasking the beautiful colors we associate with autumn. As the season progresses, the leaves will eventually drop. In Chicago, our trees usually reach peak color in the first two weeks of October, and aren’t usually bare until late October or early November.

But this isn’t a regular year. The heat we’ve been feeling lately is a factor.

Fall leaf color

Expect color, but this year’s display will be shorter than usual.

“The higher the temperature, the faster the processes go,” Tankersley said. And this month’s drought is why we’re also seeing leaves dropping only a few days into fall. Local rain gauges have been virtually dry, with less than 2 inches recorded in the month of September.

“Trees don’t have minds, but they do respond to environmental clues. If there’s been little rain, they will drop their leaves early in order to conserve water and get through the rest of fall and winter,” he said.

If you’re a fan of getting family portraits done with a backdrop of colorful foliage, Tankersley suggests getting those done sooner rather than later.

“This year, we’re going to have to be a little bit more proactive about getting out there and getting photos as the trees come into color. They’re just not going to hold.”


©2017 Chicago Botanic Garden and my.chicagobotanic.org

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

Moving Houseplants Back Indoors

Tom Weaver —  September 23, 2017 — 3 Comments

In spite of the recent 90 degree temperatures, it’s time to start thinking about moving your houseplants inside.

The best time to do this is when temperatures outside are relatively close to the temperatures indoors, meaning mid- to late September. Before you move everything in, however, there are four quick steps you’ll want to take to help ensure a successful winter of windowsill gardening.

The same care tips also apply to overwintering tropical plants such as palms and bromeliads

The same care tips also apply to overwintering tropical plants, such as palms and bromeliads.

1. Clean up any dead or damaged growth.

Why bring any additional mess indoors when you don’t have to? Carefully remove any broken branches, sunburned leaves, or otherwise unsightly growth from your plants.

2. Lightly trim back plants as needed.

This step is a bit optional, and you really only need to do it if your plants have become large and overgrown. Never remove more than one-third of the growth at a time. Removing more can stress the plant and send it into shock, which can be hard to recover from indoors.

3. Check thoroughly for pests, and treat as needed.

One of the biggest ways to set yourself up for success is to start with clean plants. There are several pests that can cause problems indoors. The most common are mealybugs, spider mites, scale, and aphids. Insecticidal soap is a lower toxicity insecticide that is safe for most houseplants and will take care of nearly any pest problem you might have. As with any chemical, make sure to follow all package instructions. It is NOT recommended to use soapy water—this eats away at the cuticle (a protective waxy layer on the leaf), making it more vulnerable to disease problems in the future. For specific pest recommendations, contact our Plant Information Service.

Large-leaved plants are particularly susceptible to spider mites.

Large-leaved plants are particularly susceptible to spider mites.

Spider mites can also cause brown edges that mimic sunburn. Look for the telltale webbing to determine if you have mites.

Spider mites can also cause brown edges that mimic sunburn. Look for the telltale webbing to determine if you have mites.

Mealybug feeding on the stem of Dioscorea elephantipes

Mealybug feeding on the stem of Dioscorea elephantipes

Sunburn causes brown spots on leaves.

Sunburn causes brown spots on leaves. Trimming off damaged leaves helps keep plants looking good all winter.

4. Finally, resist the urge to repot unless necessary.

Sometimes plants have simply grown too large for their pots, in which case it’s OK to repot. But don’t repot if the plant doesn’t need it, as this will add unnecessary stress that could harm the plant in the long term. Always use soil specifically for containers (potting soil). Black dirt is too heavy and will encourage rot. When repotting, select a new pot that’s only 1 or 2 inches larger in diameter. Anything much larger than that will encourage rot because the soil will stay wet for a long time.


©2017 Chicago Botanic Garden and my.chicagobotanic.org

Inspired by the plants and insects in their garden, jewelers Roberta and David Williamson will be among 145 artists from across the country showing their handcrafted work this week at the American Craft Exposition (ACE). The juried exposition at the Chicago Botanic Garden is also a fundraiser for the Auxiliary of NorthShore University HealthSystem.

Roberta recalls the early days of her work, when, shortly after her daughter was born, she peered out the window and observed a mother bird feeding its young. She marveled at its instinctual behavior and how the scene symbolized her own experience. The artist was inspired to create a series of charms for necklaces depicting stories of nature such as that one, which she later told to her young child. “I always see those kinds of connections between people and nature and how inspiring that is,” she said.

It is that type of inspiration that has energized her work each year, leading to new creations that she and David craft with much thought and care. “We are great observers of nature and incorporating that into the work,” she noted. “People who collect our work come year after year and we think about them as we are creating the work, and know who will love which piece…they are growing with us and that’s amazing.”

Dave and Roberta Williamson

Dave and Roberta Williamson

Based in Ohio, the Williamsons are also professors of art at a liberal arts college near Cleveland. The natural-born teachers enjoy sharing the stories of their art with students and visitors to ACE. At home, they are avid gardeners, working across their one-acre property as much as possible to plant urns and work with their favorites—foliage and flowers. “We plant and really enjoy that process,” said Roberta. “We are passionate about it and just being so in touch with nature, we bring that to the work. Many of our pieces are about plants and the insects that inhabit the garden.”

As much as nature enhances their work, the jewelers also find inspiration in other sources. “I think besides the garden and any insects and birds, the other part that we are really interested in is antique etchings, but primarily the early costumes of royalty and the embellishment on the clothing that they wear,” said Roberta. Both interests can be seen in much of the body of work they create each year.

Just as their own stories have evolved over the years, such as Roberta finding a love of nature after moving from Chicago to the suburbs as a child, the story of each piece of their jewelry evolves from the time they begin to create it to the life it takes on when it is in the hands of a new owner.

ACE cannot come soon enough for the couple, who are energized by the atmosphere of the event, the presence of their fellow artists, the event committee, and the lush setting of the Garden. “I just hope that a lot of people will be able to come to see how spectacular the combination of the art in the show is beside the Botanic Garden. I think their spirits will be so lifted that it will be really magical,” Roberta said.

Roberta & Dave Williamson, Abundance, 2010. Photo by James Beards

Roberta & David Williamson, Abundance, 2010. James Beards photograph, via craftinamerica.org

The American Craft Exposition opens with a Benefit Preview on Thursday, September 14, and is open to the public Friday through Sunday, September 15 to 17. Proceeds from ticket sales support research into orthopaedic regenerative medicine and pharmacogenomics, or how changes in one’s DNA affect the way the body responds to medication.


©2017 Chicago Botanic Garden and my.chicagobotanic.org

The Supreme Court has been asked to opine on many critical issues of its time. These cases have had profound impacts on our society and even the progression of democracy. But perhaps the most important Supreme Court case of all time—at least if you are a hard-core plant geek—was Nix v. Hedden, 1893, in which the Court ruled that the tomato is, for the purposes of taxation, a vegetable.

In the spring of 1886, the Nix family made their living importing tomatoes into New York City from the West Indies. Based on the Tariff Act of 1883, the New York Port tax collector assessed a duty on these imported tomatoes. The Tariff Act required a 10 percent duty on “vegetables in their natural state…” But, the Nix family contended, a tomato is a fruit, botanically speaking, and should not be taxed as a vegetable. The New York tax collector was unmoved by this argument and forced the family to pay the tax, though he did record that the tax was paid under protest.

Blindfolded Lady Justice weighs a tomatoPeople were just as reluctant to pay taxes in 1886 as they are today, and as any good botanist of the nineteenth or twenty-first centuries would tell you, the tomato is indeed a fruit. Its tissues derive from the reproductive organs of the plant (and contain seeds), making it a textbook fruit. It’s not even botanically confusing like the oddball strawberry, which is technically a swollen receptacle that holds fruits (the little black achenes on the strawberry’s surface). A tomato is about as clearly a fruit as there is, botanically speaking.

Yet, in common language, we tend to think of fruits as sweet and vegetables as savory. Or perhaps more basically, fruits are for dessert and vegetable go with the main course.

When the tax assessor for the New York Harbor used the common language meaning of tomato as the rationale to levy a tax, in opposition to the botanical definition used by the Nix family, I doubt he knew he was opening a legal can of worms that would end up in the Supreme Court.

The Nix family sued the tax collector. The case was heard by the Circuit Court of the Southern District of New York. The case primarily consisted of entering into testimony the dictionary definitions of fruit and vegetable. The court sided with the tax collector, and the Nixes appealed. Somewhat amazingly, the Supreme Court agreed to hear the case, and registered judgement on May 10, 1893.

By this point, the case was not so much about whether or not a tomato is botanically a fruit. In fact, in his opinion, Justice Horace Gray of Massachusetts freely admitted that “botanically speaking, tomatoes are the fruit of the vine…” But he made a distinction between the common language of the people and the botanical definition. Specifically, he noted that tomatoes are “usually served at dinner in, with, or after the soup, fish, or meats which constitute the principle part of the repast, and not, like fruits generally, as dessert.” He even cited from Supreme Court precedent. In 1889, Robertson v. Salomon, the Court held that, again for tax purposes, white beans (which definitely are seeds) should be taxed as vegetables, and not classified as seeds, which were exempted from taxation. Justice Joseph P. Bradley of New Jersey wrote of white beans, “We do not see why they should be classified as seeds, any more than walnuts should be so classified. Both are seeds, in the language of botany or natural history, but not in commerce nor in common parlance.”

Grape tomatoesRead more about cultivating tomatoes in our Tomato Talk series on Facebook (#CBGTomatoTalk) and at chicagobotanic.org

The Supreme Court unequivocally stated in Robertson v. Salomon and then reaffirmed in Nix v. Hedden that a technical definition should not necessarily stand in the way of an ordinary or common meaning. According to the high court, tomatoes and white beans are not fruit and seeds, respectively. They can, and should, be taxed as vegetables.

These cases are important to legal history in delineating the differences between technical and common usages of words under legal dispute. But what should a botanist learn from this legal tomato obscurity?

Principally, science and the law are quite different systems. You may conflate them at your own peril. Scientific logic is not always compatible or supported by legal doctrine. Under the law, up can be down, black can be white, and tomatoes aren’t fruits.

And above all, it’s very hard to avoid paying taxes.


Dr. Ari Novy

Dr. Ari Novy

Guest blogger Ari Novy, Ph.D., is chief scientist at the Leichtag Foundation in Encinitas, California, and a research collaborator at the National Museum of Natural History in Washington, D.C. He’s interested in pretty much everything about plants, including obscure legal minutiae.


©2017 Chicago Botanic Garden and my.chicagobotanic.org