Taking advantage of Missouri’s numerous, beautiful nature trails can be a healthy getaway, but hikers should take note of this poisonous plant if they hope to go home without a problem.
Toxicodendron radicans – more commonly known as poison ivy – is found all over Missouri and can grow as a shrub or vine.
Not to be confused with poison oak or poison sumac, the Missouri Department of Conservation reminds residents that only ivy is a prevalent issue in the state; poison oak is rare, and sumac has never been found here.
In fact, poison ivy is so common, MDC reported its presence in every county of Missouri, with the ability to grow in every terrestrial habitat and in nearly fully shaded areas.
Kenton Lohraff, Directorate of Public Works Natural Resources branch chief, said the plant is most easily spotted by its three leaves, where one leaf is in the center on a longer stalk, and one leaf is attached to each side.
“Individual poison ivy plants can be quite variable with differing characteristics depending upon growing conditions,” he said. “However, poison ivy tends to be vine-like with aerial roots, and it also has a longer stem on the middle leaflet.”
Although some people are naturally immune to its harmful effects, according to MDC, between 50 to 70 percent of people experience physical reactions such as rashes and blisters when exposed to poison ivy.
“Different people have different biochemistry and have differing reactions to the toxin,” Lohraff said. “Individual sensitivity can also change throughout a person’s lifetime, so once-immune does not always guarantee immunity; be smart with exposure.”
MDC officials encourage avoidance as the No. 1 way to deal with the plant. The office recommends wearing long sleeves, pants and protective boots when hiking.
Lohraff said it is important to remain calm if exposed to the poisonous substance.
“Minimize contact, don’t panic, and rinse with cold water, if possible,” he said. “Launder clothing and wash exposed skin as soon as possible.”
The actual poisonous substance that comes from the plant is called urushiol, which is Japanese for lacquer. MDC reports that urushiol is so powerful, just enough to cover the head of a pin is enough to make 500 people itchy.
But there is hope: poison ivy rashes are easily treated.
The U.S. Fish and Wildlife Service recommends using a cool-water compress with a cloth and adding baking soda or oatmeal to reduce the itchy feeling. Many anti-itch creams are available in pharmacies over the counter. Symptoms may last from days to weeks, according to FWS, and especially severe cases should be evaluated by a medical professional.
The government agency strongly warns citizens not to burn poison ivy, as the urushiol can be inhaled and cause respiratory failure or even death.
Lohraff said as far as poisonous plants go, poison ivy is the main culprit around the installation, but residents may also want to keep an eye out for stinging nettle.
“Stinging nettle is a common plant (usually near a stream),” he said. “Reaction to stinging nettle is often a severe itching or burning feeling, but short in duration – a few minutes.”
Park services try to limit the amount of poison ivy hikers may be exposed to, but with the plant’s stalwart growing ability, some may fall through the cracks, so it’s important to stay aware and stay away.
“Don’t fear nature,” Lohraff said. “Just learn to identify and respect potentially harmful organisms like poison ivy and enjoy our wonderful natural environment.”
For more information on poison ivy, and for a full list of Missouri’s common poisonous plants, visit the MDC’s field guide at https://nature.mdc.mo.gov/safety-concerns/poisonous.