Leaves of Three, and Other Plants to Avoid
Not every hazard in the woods has teeth or claws. Sometimes the biggest trouble on a hiking trail is growing quietly along the path.
Many hikers and campers have experienced the misery of brushing against the wrong plant without realizing it until hours later. An itchy rash, burning skin, or painful irritation can quickly turn an outdoor adventure into an uncomfortable experience. Plants like poison ivy, poison oak, and poison sumac are common across much of North America. Other plants, such as stinging nettle or wild parsnip, may not be poisonous, but they still have natural defenses that can set off a reaction.
The good news is that you don’t need to be a botanist to stay safe. Learning to recognize a few key plants and developing simple trail habits can greatly reduce your chances of a painful encounter.
Imagine you grab a branch to steady yourself, or are merely gathering firewood for your campfire. Not too long later, you begin to feel a burning pain or an itchy rash pops up. You’ve accidentally brushed up on some kind of poisonous plant that could possibly ruin your camping trip. When it comes to skin irritation, there are a group considered the Big Three – poison ivy, poison oak, and poison sumac. Learn to identify them so that you can give them a wide berth outdoors.
Poison ivy is the plant most hikers and campers are familiar with, and for good reason. It grows throughout much of North America and can appear in several forms including a low ground plant, a shrub, or a climbing vine on trees. The easiest way to remember poison ivy is the well-known phrase, “Leaves of three, let it be.”. Each cluster of poison ivy contains three leaflets. The leaves are often shiny and may turn reddish in spring or fall. It can grow as a ground plant, a bush, or a climbing vine. Poison ivy contains an oily resin called urushiol, which causes an itchy rash for most people. What many hikers don’t realize is that this oil can remain active on clothing, gear, and tools long after contact. Simply touching contaminated equipment can cause the rash later.
Poison oak looks similar to poison ivy but its leaves resemble the rounded shape of oak tree leaves. Like poison ivy, it typically grows in clusters of three leaflets. Poison oak is most common in western and southern parts of the United States, though hikers may encounter it in other regions as well. Contact with poison oak causes the same type of rash as poison ivy because it also contains urushiol oil.
Poison sumac is less common but often causes stronger reactions when contact occurs. Unlike poison ivy and poison oak, poison sumac grows primarily in wetlands, swamps, and marshy areas. Instead of three leaves, poison sumac has 7 to 13 leaflets arranged in pairs along a stem, with a single leaflet at the tip. The plant also produces clusters of pale gray or white berries. Fortunately, because of its preference for wet environments, most hikers encounter poison sumac less frequently than poison ivy.
Not every troublesome plant is technically poisonous. Some plants simply have defenses that cause irritation or pain when touched. Stinging nettle is covered with tiny hairs that inject irritating chemicals into the skin. Contact often causes a burning or tingling sensation that can last for several minutes or even hours. These plants commonly grow along trails, rivers, and shaded areas. Thistles are easy to recognize thanks to their sharp spines. Brushing against them can result in painful punctures or scratches. They often grow in open fields, along trail edges, and in disturbed soil. Wild parsnip can cause a condition called phytophotodermatitis, where the sap reacts with sunlight and leads to severe skin irritation or blistering. The plant produces yellow umbrella-shaped flower clusters and commonly grows along roadsides and trails. Though rare, giant hogweed can cause serious burns and blistering when its sap contacts skin and is exposed to sunlight. Because of the severity of reactions, it is best avoided entirely if encountered.
You don’t need to become a botanist to stay safe outdoors. Learning a few simple habits can help you avoid most plant-related problems. Stay on established trails whenever possible. Problem plants may have been trampled by others, or they were cleared if the trail was groomed. Avoid grabbing unknown plants for balance. Use trekking poles instead. Wear long pants when hiking through dense vegetation with longer socks. You can also tuck your pants legs into the socks. Learn to recognize a few common plants in your area, or if you’re in a new part of the country, find out which plants are prominent there and learn to identify them. Taking a few minutes before a trip to review plants common to the region can go a long way toward preventing unwanted encounters.
Teach children about the risks of touching plants when they’re outdoors. Each time you take them hiking, point out plants to avoid and let them examine them, at a distance, so that they can identify them on their own. Nature bookstores carry books and pamphlets with pictures to help kids learn what to avoid.
Even experienced hikers occasionally brush against poison ivy or other irritating plants. If you believe you've made contact, acting quickly can reduce the severity of a reaction. After exposure, wash the affected skin with soap and cool water as soon as possible. Prompt cleaning helps remove the plant oils before they fully bind to the skin. Keep hands away from your face. Avoid scratching the irritated area because you’ll infect it and can cause it to spread. Wash clothing and gear that may have touched the plant. That includes pets that might have brushed against them, too. Use calamine lotion or hydrocortisone cream to reduce itching, items you should have in your camping gear. Seek medical attention if swelling, spreading rash, or severe irritation occurs.
Know when to seek a doctor’s help. Most plant reactions resolve on their own within one to three weeks, but medical attention may be needed if the rash spreads widely or if the face or eyes are affected. Also, if severe swelling occurs or breathing becomes difficult, those can be signs of a severe reaction. Call for help. A healthcare provider may prescribe stronger medications such as oral steroids for severe reactions.
If you’re spending time in areas where poison ivy or stinging plants are common, consider adding a few items to your hiking kit. Travel-size soap, antihistamine tablets, hydrocortisone cream, anti-itch spray, and alcohol wipes. They take up little space but can make a big difference if you encounter irritating plants. Some outdoor enthusiasts also use traditional remedies for mild irritation. These treatments are not guaranteed but may provide relief for minor exposure. Aloe vera, a baking soda paste, or cool mud compresses in an emergency. These remedies may help soothe skin, but washing the oil off quickly remains the most important step.
A few pieces of outdoor gear can help minimize plant exposure while hiking or camping. Long pants, gloves, and trekking poles help keep your hands away from vegetation. When clearing small vines or trimming cordage around camp, a compact utility knife such as those from OLFA Works (www.olfaworks.com) can be useful. Having the right tool allows you to cut away small branches or prepare kindling without grabbing unknown plants directly. Small precautions like these make a big difference when camping in areas with thick vegetation.
Many hikers follow a few simple rules when dealing with unfamiliar plants. Leaves of three, leave it be is a rhyme almost everyone knows about poison ivy. Hairy vines, don’t touch them! Don’t eat unknown berries or mushrooms. If you can’t identify it, avoid it. Don’t burn unknown plants in campfires. The smoke can irritate your lungs. These simple habits help reduce the chance of an uncomfortable reaction during your trip.
A great day on the trail shouldn’t end with days of itching, burning skin, or a painful rash. Fortunately, most encounters with poisonous or irritating plants can be avoided with some awareness and a few simple habits. Learning to recognize common plants like poison ivy, poison oak, and poison sumac, and knowing how to avoid them, can make a big difference in your comfort and safety outdoors.
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