As I was walking through a field recently in the Boston area, the back of my hand brushed against a 3-foot-tall, weedy-looking plant growing on the side of the trail.
Almost immediately my hand began to sting and itch. It was quite painful, and felt similar to fire-ant bites I had received in the Everglades in Florida a number of years ago.
I took a closer look at the plant to see if there were ants or bees or some other insect on it that might have stung me. There were no bugs, but I did notice the stem and leaves had small hairs on them.
The more I rubbed my hand, the more painful and irritated it felt. Thankfully, after about 10 to 15 minutes, the pain and itching went away.
It turns out the plant I had run into was a stinging nettle.
I e-mailed Dan Jaffe of the New England Wildflower Society in Framingham to learn more about these unusual plants.
“Stinging nettles are covered in hollow hairs filled with a variety of chemical compounds that cause the stinging sensation,” Jaffe said. “The hairs impale the skin when they come into contact with it, releasing their compounds into the body and causing the irritation.”
According to a blog site called indefenseofplants.com, the hairs Jaffe mentioned are called trichomes, and the chemicals they inject into the skin that cause itching and burning include histamine, acetylcholine, and serotonin.
Jaffe said the stinging hairs have evolved as a defense against herbivorous animals, like rabbits and deer, that might try to eat the plants.
As for treatment following an encounter with a stinging nettle, an online site called Healthline warns against rubbing the rash for at least 10 minutes, like I did, because that can push the chemicals deeper into the skin, and make the rash last longer. After 10 minutes or so, wash the area with soap and water, or gently rub the area with a clean, dry cloth if soap and water are not available.
This should help to remove the stinging hairs and chemicals from the surface of the skin, and relieve the stinging sensation. After wiping the area off, use tape to remove any remaining nettle hairs that might be stuck in the skin.
Healthline said the rash tends to clear up pretty quickly, but in some cases it can last up to 24 hours, and in rare cases some people may be allergic to stinging nettles, and can experience symptoms such as swelling of the mouth, tongue, and lips, or wheezing and difficulty breathing. If this happens, call a doctor’s office or go to an emergency room.
Jaffe said applying ice to the affected area or taking an antihistamine may help as well. He added that despite the stinging sensation, there is no real threat posed by stinging nettles for the majority of people.
Of course the best way to avoid getting stung by a stinging nettle is to learn what they look like and avoid them.
Jaffe recommended checking out New England Wildflower Society’s Go Botany site at gobotany.newenglandwild.org to see what stinging nettles look like, and to learn how to identify them.
Jaffe said wearing long pants and boots while walking in areas with nettles is a good way to avoid being stung as well.
Go Botany said stinging nettles can be found in man-made or disturbed habitats, in the flood plains of streams, along the edges of forests, and along the shores of rivers or lakes.
Jaffe said stinging nettles are widespread across the United States, and can be found throughout Massachusetts. He said he often finds them growing in moist meadows. Jaffe said that like most other plants in our area, stinging nettles emerge in spring and are present until the cold season kicks in.
As for me, the next time I go hiking in areas that might have stinging nettles I’ll follow Jaffe’s advice and try to wear long pants and a long-sleeve shirt, and give any plant that looks like a stinging nettle a wide berth!
Don Lyman is a biologist, freelance science journalist, and hospital pharmacist who lives in the suburbs north of Boston. E-mail him your questions about nature and wildlife in the suburbs at firstname.lastname@example.org.