By Jen Stengle (Cornell Cooperative Extension, Putnam County), Linda Rohleder (New York / New Jersey Trail Conference), and Jessica Schuler (NYBG).
You might have noticed them crawling in your curtains, or buzzing around your house lamps; alarming numbers of brown marmorated stinks bugs settled down for winter this year. These alien invaders are just one of many invasive species that have taken hold in the Hudson Valley. Perhaps you have noticed Japanese stiltgrass (Microstegium vimineum) in a park or have seen viburnums eaten to shreds by Viburnum leaf beetle (Pyrrhalta viburni). These invasive plants and insects are just the ones we see. There are many others we don’t notice, clinging to the bottom of boats, hiding beneath the bark of trees, nestled in firewood, or attaching themselves to clothes or shoes—as in the case of seeds.
We have a strong science department at The New York Botanical Garden. Botanists of all backgrounds come here to work on topics that span each corner of the discipline, from ethnobotany to plant genomics. The scientists host Friday lectures where members of their staff or researchers from the wider community come to give presentations of their work. During the quiet winter months, I sometimes have the luxury of attending these seminars.
A few weeks ago, I attended a seminar on invasive plants. Invasive plants are an important topic for anyone who is interested in the environment and their community. With over $120 billion being spent annually on removal of invasive weeds (whether in the realm of agriculture, roadside maintenance, or habitat restoration), invasive plants are a very real problem. I always hear about it from the standpoint of a gardener and an educator. It was interesting for me to hear it from the perspective of a botanist and an ecologist. Not surprisingly, many of the warnings, lessons and take home messages were the same.
Hello from Leah and Francesca! We are high school students interning for the summer here at The New York Botanical Garden. We are working on research projects for science competitions like the Intel Science Talent Search (Another NYBG high school intern’s project made it into the finals of this prestigious competition this year!). We will both be seniors in September, Leah Buchman at South Side High School in Rockville Center, and Francesca Giordano at Yorktown High School. This summer we are both working on an expansion of projects that we began in the summer of 2010.
Bee on the Seasonal Walk - Photo by Leah Buchman
Leah’s Project
Last summer, I did a study on the diversity of bees within different areas of the Garden. I caught bees in 10 areas of the Garden and learned to identify the bees with help from Dr. John Ascher at the American Museum of Natural History. Using four different indices of diversity–evenness, abundance, richness, and Shannon-Weaver diversity–I was able to conclude that there is a higher diversity of bees in areas that have a greater diversity of flowers.
The specific area of the Garden that has the highest diversity is the Seasonal Walk. This summer I am looking at the gender of bees to see if there is any correlation to the flowers visited. For example I am hoping to answer questions like: Do male bees go to certain flowers while females go to others? Feel free to come stop by and say “Hi!” I will be the girl with the net and bright colored bowls in the Perennial Garden, Ladies Border, Seasonal Walk, and Home Gardening Center this summer.
NYBG Volunteers Clearing Japanese Knotweed - Photo by Francesca Giordano
Francesca’s Project
My research is a study on management of the invasive plant, Japanese Knotweed. Now you’re probably thinking: What is an invasive plant? Little did you know, but plants can be pretty vicious, especially Japanese Knotweed. It is a non-native plant that grows rapidly and blocks sunlight from reaching desired plants. Japanese Knotweed is also known for having an underground stem called a rhizome. This rhizome contains the stores of energy that the plant uses for growing, plus additional reserves. The rhizomes contain enough energy to allow one plant to sprout over 250 shouts just from a single underground stem! Our goal is to increase the diversity of the native plants along the Bronx River by using best management practices to control the Japanese Knotweed.
What we found so far is that two treatments–cutting and grubbing the Japanese Knotweed–are equally effective. In phase two, which is the project I am working on this summer, we will be repeating the same treatments from last year in the hope that they will further weaken the persistent Japanese Knotweed and increase native plant diversity. These plots are located long the Bronx River bank just south of Magnolia Way Bridge. Come check it out and see for yourself! I am also being assisted in my field work by the Explainers and the School of Professional Horticulture, and by volunteers including groups from American Express, Goldman Sachs, and Christodora.
Gregory M. Plunkett, Ph.D. is Director and Curator, Cullman Program for Molecular Systematics
Giant Hogweed (Image from New York State Department of Transportation’s Dangerous Roadside Plants page)
From the recentnewsreports, you’d think that New Yorkers had better fly south to escape the onslaught of the diabolical giant hogweed. Even its name evokes a sort of dread, and we are reminded of the stories of “killer bees” from the 1990s.
The giant hogweed plant (know scientifically as Heracleum mantegazzianum) is native to the Caucasus, a mountainous region that separates Europe from Asia. Like so many invasive plants, this species was originally imported to North America as a garden ornamental. It’s easy to see why. The plant is an attractive, gigantic herb, reaching up to ten feet tall in just a few months, topped by huge, umbrella-like spreads with hundreds of tiny white flowers. As a consequence, each plant can make hundreds or even thousands of seeds. Inevitably, this exotic species started to jump garden fences. In our region, the plant was first introduced to Rochester, N.Y. sometime before 1920. Since then, it has been steadily colonizing New York State (see the DEC map here) and it is now approaching New York City.
Why all the fuss? Well, it turns out that giant hogweed produces a sap containing some nasty chemicals called “furanocoumarins”. These compounds easily pass into our skin cells and bind to the DNA inside. Once inside the skin, one additional ingredient is needed to activate the toxin: sunlight. Exposed to the sun, these chemicals kill the affected cells, resulting in a reaction called phytophotodermatitis. This is a nasty, itchy rash that causes discoloration of the skin (from red to dark purple) that can last for months or even years. In severe cases, it can progress, turning into large blisters that mimic second-degree burns. If the plant’s sap reaches the sensitive tissue of your eyes, this blistering could result in scarring and blindness. Yet, as bad as this rash can be, furanocoumarins have been used medicinally as a remedy for psoriasis (where it prevents cell proliferation) and vitiligo (where it darkens depigmented skin).
Most victims of giant hogweed are affected while working in weedy patches, where they are exposed directly to the sap while removing plants by hand or cutting them down using a weed-whacker or lawn mower. The good news: we have expert advice from http://www.backyardboss.net/best-string-trimmer-reviews/, their blog gave us real insight. Giant hogweed is easy to see (it’s ten feet tall, after all), and you must be exposed to both the sap and sunlight. As a result, there are two ways to prevent this nasty rash: avoid exposure to the plant, especially its sap by wearing long pants, long-sleeved shirts, and protective eyewear in areas where giant hogweed grows (unlike the NYS DOT workers above), and avoid exposure of your skin to the sun for the next few days if you do accidentally touch it.
As it turns out, giant hogweed is not the only plant that can cause phytophotodermatitis. Many of its relatives in the plant family Umbelliferae also produce furanocoumarins, including carrots, parsnips, fennel, and celery, but the level of toxins in these species are typically lower. The same family includes other toxic plants, such as poison hemlock, as well as many useful herbs and spices like dill, parsley, cilantro/coriander, and caraway. The same class of compound are produced in completely unrelated plants, too, such as the wild relatives of tomatoes and strawberries, and in the rinds of lemons and limes. You may have heard of the dangers of making lemonade in the sunshine!
Finally, before you sell the house in New York and move to Florida, remember that we have already learned to deal with other nasty plants that cause terrible skin rashes and even blindness, including poison ivy and stinging nettles. Even though these native plants are harder to recognize, we have learned to deal with them. And one last reminder before you sell you house and head for Florida: We New Yorkers may have to deal with snow and giant hogweed, but at least we don’t have alligators, fire ants, and killer bees!
Sonia Uyterhoeven is Gardener for Public Education. Join her each weekend for home gardening demonstrations on a variety of topics in the Home Gardening Center.
Years ago, I returned home to Massachusetts after living in England for 10 years and drove around my old neighborhood with a friend. I commented on a pretty purple flower I saw growing in a wetland area. When I asked her what it was, she cringed and told me it was purple loosestrife (Lythrum salicaria, pictured. Photo by Wikipedia user Meggar). At first I thought her reaction was severe until, continuing our drive, I realized it had taken over many wetland areas. Where were the native cattails (Typha), the sedges (Carex), and the swamp milkweed (Asclepias incarnata) that I had grown up with?
Ecosystems are by definition complex, and the lives of their inhabitants are interconnected. When an ecosystem is thrown out of balance by an invasive intruder, more than the flora suffers.
Insects, birds, amphibians, and mammals all depend on the native flora for food, shelter, and nesting sites and materials. An area stripped of its native vegetation creates a sterile environment that is no longer inhabitable to many creatures.
You might have noticed them crawling in your curtains, or buzzing around your house lamps; alarming numbers of brown marmorated stinks bugs settled down for winter this year. These alien invaders are just one of many invasive species that have taken hold in the Hudson Valley. Perhaps you have noticed Japanese stiltgrass (Microstegium vimineum) in a park or have seen viburnums eaten to shreds by Viburnum leaf beetle (Pyrrhalta viburni). These invasive plants and insects are just the ones we see. There are many others we don’t notice, clinging to the bottom of boats, hiding beneath the bark of trees, nestled in firewood, or attaching themselves to clothes or shoes—as in the case of seeds.
