Emerald ash borer appears to have spread to a different host, and has now been found and confirmed at the Chicago Botanic Garden. But there’s no need for us to panic—it’s just an interesting find to document.
As I blogged in late 2014, a college biology professor in Ohio (Don Cipollini, Ph.D., of Wright State University) discovered emerald ash (EAB) borer attacking white fringetrees (Chionanthusvirginicus). Soon after his discovery in 2014, the Garden monitored its fringetree collection and found no signs of EAB activity on our fringetree collection (around 40 trees).
Two weeks ago I had the privilege of meeting Dr. Cipollini here at the Garden and scouting our fringetrees with him. Cipollini and a Ph.D. student are studying EAB on fringetrees and are scouting known populations of fringetrees in areas of EAB activity. Where better than a Garden like ours with a documented collection of fringetrees?
We scouted nearly all of our fringetree collection very closely. Cipollini knew exactly where to look (way beyond the obvious) and carefully reviewed each of the Garden’s fringetrees. About halfway through the scouting process, a suspicious sunken area was found on one tree. With a sharp chisel, a small section of bark was scraped, revealing a borer gallery. We later removed the limb and found a D-shaped EAB exit hole not far from the gallery. Cipollini indicated that he felt the damage was about 2 years old, and this coincides with time that EAB was at its highest level at the Garden. Of all the trees we very closely monitored, we found only one that had been very slightly damaged by EAB.
We do not need to start treating our fringetrees for EAB or recommend it. The damage is old, and took place when EAB was hitting the Garden the hardest a couple of years ago; so at very high population pressure, it makes sense that they may feed on another closely related tree or shrub. Ash (Fraxinus) is in the olive family (Oleaceae), as is fringetree (Chionanthus), lilac (Syringa), Forsythia, privet (Ligustrum) and swamp privet (Forestiera). These other shrubs are being monitored as well, but it is thought that they may not be an attractive alternative host, as the EAB does not seem to go after small-diameter branches that are prominent on these other olive family shrubs.
As I mentioned in my earlier blog post, I do suggest if you have a fringetree that you look it over for signs of EAB activity.
If you are a plant and bug person like me, please consider becoming a NPDN First Detector and help be on the lookout for these exotic plant pests and pathogens. The NPDN offers an online training course to become a First Detector at firstdetector.org. It’s free, and upon completion, you even get a printable certificate!
Come to the Seed Swap on February 28, and see a demonstration of the Lenhardt Library’s new seed library, set to launch next month.
Seed sharing is a resource for the community, just as libraries are a community resource for books. A seed library is where one may “borrow” seeds to sow, and if successful, harvest, save, and return some to the library for others to borrow the following season. We aim to cultivate an interest in home gardening and seed saving.
Many are familiar with planting seeds, so we’ll focus on seed saving—a less familiar aspect of the food cycle. The Lenhardt Library’s seed library will be geared toward the novice who has little experience with seeds, but all are welcome to participate. We’ll provide horticultural assistance and step-by-step instructions as part of our program.
Seeds in this seed library are primarily heirlooms (varieties that have been in cultivation for 50 years or more), and/or open-pollinated (pollinated by bees or wind), so that the next generation seed retains the identical characteristics of the parent. Seed companies Renee’s Garden and Seed Savers Exchange have generously donated seeds to get us started; tomato, beans, lettuce, and more await you.
In 2015, the Illinois Seed Law was amended, making noncommercial seed libraries such as this one legally exempt from commercial requirements such as testing and labeling. Now we’re ready to get started!
We hope you’ll visit and borrow seeds for your home garden, whether it’s a large plot or a terra cotta pot on a windowsill.
The first time you walk under a big, lush tangle of orchid roots at the Orchid Show can be quite disconcerting—what are those big white things dangling in the air, you wonder, and how do they work?
Let’s look at those roots from a different angle, so that the next time you walk under them, you’ll know more about what you’re seeing.
They’re Called Aerial Roots
Of the 27,000-plus species of orchids on the planet, about 70 percent are epiphytes—plants that grow on trees, with above-ground rather than in-ground roots. Known as aerial roots, they act as anchors and supports as they wrap around branches and trunks, stabilizing the plant as it grows. Roots are an orchid’s lifeline, absorbing water and nutrients from the air and from the leaf litter in the tree niche it inhabits.
Orchid Roots Are Adventitious
That is, an orchid’s roots can grow along the stem of the plant, not just out of the bottom of it. The advantage of being adventitious? Plants can be propagated easily. Many orchids grow baby plantlets, called keikis, that can be removed from the mother plant along with their own set of adventitious roots.
The White Stuff Is Velamen
An aerial root should look fleshy and green; the white coating that covers it is called the velamen. Thin and rather papery, but spongy and protective, it’s a one-way water barrier that allows moisture to soak in—and keeps it from oozing out.
If the velamen appears dried or rotted, it should be stripped off up to where it’s healthy and white, leaving the wiry inner root to help stabilize the plant once it’s in the pot.
Roots Signal Plant Health
At the Orchid Show, you get to see lush, healthy roots close up. At home, your orchid’s roots will usually be contained in its pot. Roots growing out of and over the edge of a pot signal that it’s time for re-potting—which gives you the opportunity to examine your plant for overall root health. Plump, green roots look and are healthy; yellow, spotted, black, or dried out roots indicate that it’s time to re-think how you’re caring for your orchid.
Roots Can Rot
Overwatering is the number one threat to an orchid plant. Orchid roots rot easily if given too much water—with no switch to prevent roots from pulling in excess water, the plant can drown if left standing in a full saucer. That’s one reason why orchid pots typically have extra drainage holes.
To correctly water an orchid, remove the pot from its saucer to the sink. Run water gently but thoroughly through the plant for a minute or two. Then allow the plant to drain completely before returning it to its saucer; repeat weekly.
Orchid roots are awesome! Come see for yourself at the Orchid Show, running through March 13, 2016.
Peter DeJongh is a first-year master’s student studying land management and conservation in the graduate program at Northwestern University and the Chicago Botanic Garden. His academic focus is on developing strategies to optimize plant and wildlife conservation and restoration. He aims to work in applied conservation or environmental consulting upon completion of his degree.
Imagine a large, beautiful canopy tree standing in the middle of a lush, tropical rainforest. This centuries-old tree produces thousands of seeds every year that densely litter the forest floor around it. Where then would you imagine its seedlings are likely to spring up? Probably in the seed-covered area around the tree right? Well, according to the Janzen-Connell model, you’d be wrong.
Daniel Janzen and Joseph Connell are two ecologists who first described this phenomenon in the early 1970s. They put their exceptional minds to the task and independently discovered that the probability of growing a healthy seedling was actually lower in the areas with the most seed fall. They hypothesized that seed predators and pathogens had discovered the seed feast around the parent tree and moved in, preventing any seeds in the area from growing into seedlings. These predator pests include beetles, bacteria, viruses, and fungi, and have been labelled as host-specific predators and pathogens since they appear specifically around the parent tree, or host.
Janzen and Connell’s hypothesis shows just how important the animals that eat the seeds are to the parent tree. These primates, birds, and other vertebrates move the seeds to different areas where they can successfully grow without being bothered by those pesky host-specific predators. Without these animal helpers, the forest couldn’t continue to grow, and the world’s most diverse areas would be in serious trouble.
Students in the Chicago Botanic Garden and Northwestern University Program in Plant Biology and Conservation were given a challenge: Write a short, clear explanation of a scientific concept that can be easily understood by non-scientists. This is our fifth installment of their exploration.
Life on the prairie hasn’t been a breeze for the beautiful eastern prairie fringed orchid (Platanthera leucophaea).
Once common across the Midwest and Canada, the enchanting wildflower caught the attention of collectors and was overharvested throughout the 1900s. At the same time, large portions of its wet prairie, sedge meadow, and wetland habitat were converted to agriculture. By 1989, just 20 percent of the original population of Platanthera leucophaea remained, and the orchid was added to the federally threatened species list.
The struggles of the captivating orchid did not go unnoticed. Its lacey white flowers and unique biological attributes sparked a passion in scientists and volunteers across the Midwest who began gathering leaf samples for genetic analysis and recording measurements on the health of certain populations. Some volunteers dedicated decades to this work, and many continue to monitor their assigned location today.
As long ago as the mid 1800s, an earlier generation of the wildflower’s enthusiasts had preserved samples of actual plants, pressing them onto archival paper with their field notes and placing them in long-term storage facilities called herbaria, for future reference. As it turns out, some of the plant materials they saved are from populations that no longer exist.
Now, all of that data is coming together for the first time in a research study by graduate student Claire Ellwanger.
The master’s degree candidate—in a Plant Biology and Conservation graduate program run by the Chicago Botanic Garden and Northwestern University—is using modern analysis tools to uncover the genetic history of the species. What she finds will give scientists a better picture of the present-day status of genetic diversity of the species, and insight into the best ways to manage it for the future.
“This orchid is a pretty interesting species because there has been this massive volunteer effort for over 20 years to restore it in Illinois,” noted Ellwanger, who said that Illinois currently houses more populations, or locations, of the species than any other state.
She is focused on collecting and analyzing genetic information on the remaining plants, working with field collectors in the Midwest from Iowa to Ohio, and also from Maine. She is examining the genes, or DNA, of each of the sampled populations, along with genetic information she collected at eight sites right here in Illinois.
Ellwanger is also extracting DNA from the older herbarium samples to better understand how much genetic diversity was a part of the species in the past. “The herbarium samples will allow us to get a sense of historic genetic variation to compare to levels today,” she explained.
Along with her thesis advisor, Garden molecular ecologist Jeremie Fant, Ph.D., she is especially interested in finding ways to maintain genetic diversity. “We know that if you are able to preserve the most genetic diversity in a species, it is more likely to persist for longer,” she explained.
In the lab today with her research assistant, Laura Steger, she uses a genetic fingerprinting technique on all groups in her study subjects. By watching the same sequence of genes over time and locations, she can see clear patterns and any changes. The bonus to it all is that “understanding more about these plants and their genetic variation will be pretty applicable to other species that have undergone the same processes,” she noted.
As scientists and volunteers worked in the field over the last several decades, they did more than collect genetic information. They also took steps to boost new seed production by hand pollinating plants or conducting a form of seed dispersal. Through her study, Ellwanger is also tracking the success of each technique. “I’ll be able to complete a genetic comparison over time to see if these recovery goals are achieving what they set out to do,” she said, by comparing the genetic composition of a given population from the recent past to today.
At sites Ellwanger visited personally, she collected seeds as well, and brought them back to the lab for examination. There, looking under a compound light microscope, she checked to see what percentage of seed embryos from the sites were plump and therefore viable. Her findings offer an additional perspective on what her genetic analysis will show. After examination, the seeds were returned to their field location.
In early analysis results, “it looks like reproductive fitness does differ between sites so it will be really interesting to see if those sites that have lower reproductive fitness also have higher levels of inbreeding,” noted Ellwanger. Inbreeding, the mating of closely related individuals, can result in reduced biological fitness in the population of plants. In such cases, it could be helpful to bring in pollen or seed from other populations to minimize mating with close relatives and strengthen populations for future generations.
The eastern prairie fringed orchid will soon be better understood than ever before. The findings of the study may also provide insight into other problems that may be happening in the prairies where they live. “Orchids will be some of the first organisms to disappear once a habitat starts to be degraded. If we can better understand what’s going on with this plant it, could help out similar species,” said Ellwanger.
The researcher is looking forward to the impact this work could have on the future of the plant and the habitat that sustains it. “What motivates me about research is definitely the conservation implications,” said Ellwanger, who developed her love of conservation while growing up on the East Coast and learning about the complex systems that play a role in the health of the environment.