When Larry Aronson stepped in to substitute for a scheduled chef during a recent Garden Chef Series demonstration, the long-time Chicago Botanic Garden volunteer brought three important things with him:
- His chef son, Richard, who helped demonstrate alongside his dad.
- Decades of cooking and restaurant experience as the owner of My Pie Pizza Unique Pizza in the Pan.
- An awesome tomato sauce recipe that he had developed especially for the Regenstein Fruit & Vegetable Garden’s Heirloom Tomato Weekend.
Aronson knows tomatoes, and he knows that many of us are just starting to pick the first ripe tomatoes from the vine. (Cooler nights have delayed ripening.) What can a gardener do with just a few tomatoes from each plant, instead of a bushel full?Make this sauce.
The flavorful sauce was a hit at the chef demonstration that day, and it was a hit with the volunteers and staff who got to sample it at a follow-up luncheon. At the latter, Aronson also served the “winter” version of his sauce—same recipe, but made with canned tomatoes instead of fresh. Both were tasty, in different ways: the “summer” version was light, bright, and refreshing; the “winter” sauce was thicker, richer, and heartier.
Aronson will have copies of his recipe on hand and will be talking tomatoes when he volunteers at Heirloom Tomato Weekend this Saturday and Sunday (11 a.m. to 4 p.m. each day). Stop by to talk tomatoes—and recipes!
We’re happy to share the recipe here, too—just in case you need it for tonight’s tomato sauce.
As plant enthusiasts, we often focus on how plants are affected by their environments. Their growth is affected by weather, water, nutrients, etc. But the plant-environment relationship is a two-way street, and plants can have a strong influence on the habitats they live in. We might experience this by walking in a forest and feeling ground beneath our feet that is spongy from the buildup of slowly decaying leaves that accumulated over decades or centuries. The trees in such a forest have “engineered” their environments, changing the very ground beneath them in ways that are beneficial to other plants, to animals, and to ecosystem functioning.
Unfortunately, we can also experience negative engineering effects of plants on their environments when we visit natural areas throughout the Chicago region and beyond that have been heavily invaded by the nonnative common or European buckthorn (Rhamnus cathartica). Buckthorn was brought to the Midwest for ornamental use—it’s great at making hedges—but escaped from human control and is now one of our region’s worst invasive species. As its hedge-producing credentials suggest, buckthorn is good at forming dense, shady thickets. These thickets have been shown to harm native plants and wildlife and to change physical, chemical, and soil conditions where they occur. Where there once may have been an open oak woodland underlain by a thick carpet of grasses, sedges, and wildflowers, we now often see an uninviting tangle of shrubs with little other than bare soil beneath them.
This contrast, between an environment that looks like this…
…and one that looks like this…
…got me and my colleague Jim Steffen wondering whether the ability of woodlands to perform carbon-storage ecosystem services could be impaired by buckthorn invasion. If so, could restoring impacted habitats back to native woodland vegetation return these services? Some background: Ecosystem services are essentially benefits nature provides to humans (e.g., clean air and drinking water, food, and other resources). Sequestering carbon—removing it from the atmosphere where it contributes to global climate change and instead locking it away harmlessly for potentially hundreds of years—is one such service.
Steffen’s more than two decades of work removing buckthorn from the Garden’s Mary Mix McDonald Woods and restoring native plant species had created the natural, long-term experiment we needed to answer these questions. We had access to areas still dominated by buckthorn for use as control treatments and patches of restored woodland of various ages that had previously been dominated by buckthorn (this is called a “restoration chronosequence”). And we had human capital to put to work: Rachel (Hesselink) Gentile and Chad Zirbel, who participated in the Garden’s Research Experiences for Undergraduates program (funded by the National Science Foundation) in 2009 and 2010, respectively. Gentile and Zirbel, in turn, mentored College First high school students Alan Lane and Kassandra Altantulkhuur.
So why did we think that buckthorn’s engineering of its environment might reduce carbon storage? Why not increase it? Mainly because of all the missed opportunities for carbon sequestration represented by the vegetation that buckthorn displaces: countless individuals of hundreds of species of understory plants, plants that make their living by drawing in carbon dioxide from the atmosphere. During photosynthesis, this captured CO2 is transformed into plant biomass, which occurs largely underground, in a complex tangle of fine, deeply penetrating roots that interact with the soil to produce tough, carbon-based compounds that are very slow to cycle back to the atmosphere. Not incidentally, all of these living understory plants and their deceased brethren (dead plant material is called “litter”) could help stabilize the soil, so that captured carbon would be less likely to wash away in thunderstorms and spring thaws.
What did we find? That buckthorn-dominated areas were indeed bad at storing carbon and that restored areas got better as they got older. Restored patches had lower rates of erosion and higher concentrations of persistent organic carbon in their soil. As restored areas matured, their vegetation continued to rebound, with plant diversity and litter biomass increasing over time. This maturation of the plant community was matched by steady increases in soil-carbon accumulation.
But wait, what about those thickets we see? Surely all that wood must be good for storing carbon? Not so much. We calculated wood biomass by measuring hundreds of trees. Even though restoration involved cutting down a lot of buckthorn, it actually led to a net increase in wood biomass, an increase that was also positively correlated with restoration age. Buckthorn’s thickets may look impressive, but its trunks and branches are puny compared to most trees, there is (almost) “no there there.” We think that taking out buckthorn may have freed native trees that can really get big, like white and red oaks, to better reach their growth potential.
In addition to the well-recognized benefits to biodiversity from active, long-term woodland restoration, our work and that of other scientists shows that there can also be tangible benefits to society. You can learn more about this research in our manuscript recently published in the journal Restoration Ecology. And you can expect to see further interesting work from Gentile (now pursuing a Ph.D. in ecology at Notre Dame), Zirbel (pursuing his Ph.D. in ecology at Michigan State), Lane (an undergraduate at DePaul University), and Altantulkhuur (attending the University of Illinois at Chicago).
Selecting perennials to look good year-round and weather the seasons outside our wall (and next to the freeway) has been a challenge! With its own group of microclimates and an often-harsh growing climate—including high winds and both flooding and drought conditions—cultivating the garden along the Garden Wall and Berm has been a learning experience.
Originally, the design for the perennial border—which you can see trailing up and down the hill behind the big Chicago Botanic Garden sign—included Tatarian aster (Aster tataricus ‘Jindai’), which stands tall in the fall and produces clouds of small lavender-blue flowers well into late October and even November. The problem with this particular plant choice was its aggressiveness. It’s not exactly invasive, but it’s a bully: its roots spread out and then shoot up a new plant every few inches, which produce a forest of these plants. Unfortunately, they soon encompassed pretty much everything in their path. Even the hearty feather reed grass (Calamagrostis acutiflora ’Karl Foerster’) began to succumb to this persistent tide of plants, strangling down into mere wisps of their former glory.
Manual removal of the asters was only part of the solution; we needed to find a replacement for these bad boys. In the process, we revisited the vision for this border, and decided to mix drifts of purple coneflower (Echinacea), blazing star (Liatris), and several varieties of ornamental grasses with a replacement for the original Tatarian asters.
The chosen replacement was a smooth aster cultivar, Aster laevis ’Bluebird’, which is new to the Garden’s plant collection. It bears flowers nearly identical in color to ‘Jindai’ and can grow to the same height as well.
Furthermore, this cultivar is more well-behaved and doesn’t spread as aggressively. Bluebird smooth aster simply grows bushier in successive seasons—a win/win situation, to be sure. The replanting process took staging and preparation that began with the removal of any grasses that would need to be relocated or divided, and these were heeled into a well-mulched bed located immediately at the site, and watered generously. Additional Echinacea, Liatris, and grasses were delivered and staged for installation. Once all of the ‘Jindai’ had been removed, it was time to plant the new group.
The new Bluebird asters came in 2-inch pots and were notably small compared to the 4-foot-tall plants they were replacing; to top it off, these were beginning to bloom in June, so the top half of these small plants needed to be trimmed off, making them even smaller. But we were confident that these plants would be well-sited in full sun, so their potential growth was a slam-dunk.
Once the grasses were in place—Panicum virgatum ’Rotstrahlbush’, Calamagrostis acutiflora ’Karl Foerster’, and Sorghastrum nutans ’Sioux Blue’—the rest of the perennials were planted, with the idea of pulling the taller Liatris more toward the middle or back of the border and allowing the Echinacea to fill toward the front. The new asters would eventually stand toward the middle and back of the bed, as tall as most of the grasses. It was important to maintain the colors placed well among the grasses, as they would be the last to bloom. Planting and mulching happened simultaneously to avoid damage to the new asters.
That was a year ago, and the border looked fine in the fall, but the question remained—how will it look this year? We’re happy to report that the Bluebird asters are rocking it: they were already as tall in July as their neighboring grasses, and they’re filling out and ready for a spectacular fall display. Of the 3,200 plants that were either moved, divided, or planted anew, the survival rate is exceptionally high: fewer than 1 percent of the plants were lost! It’s mid-August at this writing, and the colors are popping. So, the next time you drive by, carefully check it out, and enjoy this part of a lengthy border of native beauty.
|Love and Peace™ rose (Rosa 'Baipeace') is a hybrid tea featuring long, pointed buds with flowers that open golden-yellow, edged in pink. The fragrance is described as fruity, and is not overpoweringly strong. Unlike many other hybrid teas, the foliage remains on the stem all the way to the ground throughout the growing season, eliminating the need to plant annuals in front of the rose to hide the "ugly ankles." It is hardy to zone 6, so plants must be protected in the Chicago region over winter with a layer of leaves or mulch about 18" high over the crown. Love and Peace™ rose is also prone to black spot and powdery mildew — two banes of rose growers everywhere. This particular cultivar is an offspring of the famous Peace rose introduced shortly after World War II. Gardeners have been mystified by cultivar names for Rosa and other genera over the last ten years or so; they appear to be gobbledygook. (What is 'Baipeace'?) Actually, cultivar names reflect a trend among plant breeders and purveyors of new plants to protect their investment of time and money for a greater period of time. Under the system used until relatively recently, a new cultivar was patented, and the patent protection lasted for 18 years. By using a "gobbledygook" cultivar name and then assigning a "people-friendly" trademark or registered name, an originator of a new cultivar is able to obtain indefinite protection. This translates to payments to the originator for every plant of that cultivar that is sold — indefinitely.|
|Soft orange blends to golden yellow in the center of October Sky dahlia (Dahlia 'October Sky'). These formal decorative dahlia flowers are strong growers, growing to 5 feet in height with 5-inch-diameter flowers. Because of the large size of the flowers, this cultivar has a tendency to come into bloom in August (versus July for many of the smaller-bloomed cultivars). It is known for producing many lateral buds, all of which produce flowers. Plant in full sun, and stake if planted in a windy location. This is a 2011 introduction from Swan Island Dahlias of Washington.|
|Serenita™ Raspberry Summer Snapdragon (Angelonia angustifolia 'PAS777797') is a cultivar which features deep rose flowers with black throats. It grows to a mature height and width of 14 inches, and thrives during the heat and humidity of summer. A naturally dwarf specimen, it requires few, if any, plant growth regulators to control height. Plant in full sun and provide supplemental irrigation during dry periods. This plant attracts hummingbirds and butterflies.|
|A beautiful specimen with an unsettling name, the large glossy golden leaves of The Shining hosta (Hosta 'The Shining') are the perfect backdrop for the fragrant, large lavender flowers produced on 30-inch-tall spikes in August. This cultivar matures at 18 inches in height and 36 inches in width and holds color best in partially shaded locations. It requires continuously moist soils. Cut and compost old leaves at the end of the season to avoid providing overwintering locations for slugs that otherwise will eat holes in the leaves as they expand in spring.|
|Full Moon tickseed (Coreopsis 'Full Moon') is a complex hybrid of 8 different North American species of Coreopsis. It features 3-inch, canary yellow daisies atop a 2-foot mound of green foliage from July through September. Plant in full sun and water the first year to establish the root system; thereafter only during periods of drought. This is one of the first of the new hybrids created by Darrell Probst which focus on hardiness, disease resistance, large flowers, and attractive forms.|
The king cracker (Hamadryas amphinome) is our featured butterfly this week.
The king cracker is part of a larger group of butterflies called crackers because of the sound males make with their wings when they fly. You guessed it, they make a cracking sound! Only males can make the sound, but both males and females can detect it. We still don’t know why they make a cracking noise; perhaps it has to do with mating, or maybe to deter a potential predator. Regardless, it is fun to hear!
The king cracker is native to Mexico and Peru, but has been spotted in the southern United States as well. It has a very unique color pattern that is truly remarkable to see. On the top of its wings is a stunning blue and white calico pattern. Underneath is a brilliant brick-colored patch that gives the butterfly its other common name, red cracker.
The king cracker is a master of disguise. The mottled blue and white tones allow it to blend easily into the bark on trees. Tree trunks are a favorite resting spot for king crackers and they, unlike most butterflies, rest with their wings open; ready to take flight at any moment. Even the the pupae are disguised to look like withered leaves.
Another interesting fact about the king cracker is that it feeds mainly on decomposing fruit and not nectar. It is easy to spot a king cracker grabbing a quick bite on any of our four feeding dishes. So come on out to the Butterflies & Blooms exhibition and see if you can see or hear one today!