Dangerous North American Plants

8 Dangerous North American Plants to Watch for in Your Outdoor Adventures


Keep an eye out for these dangerous plants on your next adventure.

Most people who love the outdoors are keenly aware of the dangers presented by animals or the elements. But plants often get overlooked when talking about spending time outdoors.

Whether you're just out for a hike, an early-season deer hunt or are actually in a survival situation, it's helpful to do your research on the dangers of the plant world.

With that in mind, we've compiled a list of 8 dangerous North American plants outdoorsmen and women will definitely want to avoid. We've tried to compile this list starting with plants that are simply irritating before getting to some downright deadly plants.

Poison Ivy

This is probably the most common poisonous plant you're likely to encounter. You probably already have at least once. It's hard to love the outdoors and avoid running into this at some point or another. This plant causes near unbearable skin irritation.


If you've had it before, you know how annoying the itching rash you get from this plant can be. After years of immunity, it finally wore off last year and I ended up covered in the stuff for a few weeks late last summer. It isn't just the "leaves of three" that can get you either, it's also the vines that grow up the sides of trees and on occasion, walls and buildings.

Poison oak

There are two different kinds of poison oak you'll want to watch out for. Toxicodendron pubescens (Atlantic poison oak) and Toxicodendron diversilobum (Pacific poison oak).

Despite the oak name, both plants are actually shrubs that grow around 3 feet tall and normally have green leaves of three. Keep in mind, these leaves often change color much like a tree in the fall months.

They aren't related to oak trees at all, although you can sometimes find them growing near them. The oak name comes from the leaves, which look similar to an oak tree's leaves. In any case, both plants contain urushiol in their sap and leaves. This is the same stuff that makes poison ivy so itchy, and it's also present in our next plant.


Poison sumac

This plant is another shrub-type plant, but this one can grow upwards of 30 feet high. Just like ivy and oak, you want to avoid all skin contact with the green leaves plant because of the unbearable itching it can cause. Unfortunately, poison sumac is a little harder to spot because the "leaves of three" rule doesn't apply. It grows 9-13 leaves per stem.

Out of these three urushiol-containing plants, some say the worst one to get is poison sumac because it's slightly more toxic than the other two. We'll take their word on that, as we're in no hurry to put that theory to the test.

We should also mention you really don't want to be close to poison ivy, sumac or oak while it's burning. Inhaling the smoke could expose the toxins to your lungs and cause breathing difficulties. If you're ever in a survival situation, remember to be wary of the white berries of poison sumac. If you think the itching is bad, eating it can be worse. It can actually be fatal!

Unfortunately, these first three dangerous plants can be found in many parts of the U.S., making it difficult to avoid them on your outdoor adventures.


Another thing to keep in mind is the fact that these first three plants can get you even if the leaves aren't there. The toxins remain in the roots and leaves all year round. I know people who've gotten poison ivy in the winter because they didn't realize the vine they just leaned their hand on was a dormant poison ivy plant.

Water hemlock

Water hemlock is one plant you REALLY don't want to eat in any circumstances because it contains a poison called cicutoxin.

This toxin can cause all sorts of adverse effects in humans, including severe seizures, abdominal pain, nausea, vomiting and worse. In large amounts, it's even put people into comas or outright killed them.

The main reason we put this one on the list is because water hemlock is often confused with edible plants like wild parsnips, celery and carrots. In the case of the parsnips, it can get confusing because water hemlock not only looks similar, it's often found in the same areas as parsnips. Keep in mind, wild parsnips have yellow flowers while water hemlock has white flowers. The root of the wild parsnip is edible, but the sap is toxic and should be avoided. This is why it's very important to know exactly what you're eating when you dabble with edible wild plants.


There have also been some cases of this plant poisoning people simply through skin contact. It's probably a good idea to just avoid it at all costs.

Poison hemlock

This plant is very similar and sometimes mixed up with water hemlock, so it's probably another good one to know if you're gathering wild edibles. You may already know of poison hemlock as the plant that was used to kill the Greek philosopher Socrates.

Poison hemlock contains several alkaloid toxins, all of which are just plain bad for humans. Ingesting poison hemlock can have negative effects on your central nervous system. It can cause trembling and salivating. In worst-case scenarios, your respiratory system and kidneys might fail and kill you.

Poison hemlock grows 5-8 feet tall and is often topped with white flowers much like the water hemlock. Be careful, though, because this plant can also be easily mistaken for the edible Queen Anne's lace, aka wild carrots.


Deadly Nightshade

We put this one on the list because of the plant's berries. In a survival situation, they may look tasty, but eating these berries is a very bad idea. Atropa belladonna, aka deadly nightshade, was originally native to Europe and North Africa but eventually spread here to North America.

The foliage is also toxic, but the berries of this plant edible. Unfortunately they contain toxic tropane alkaloids. The berries are said to have hallucinogenic properties, but they can also poison you and cause a whole slew of problems including blurred vision, headaches, dry mouth, dilations of the pupils and more.

They can even cause increased breathing and heart rate. Deadly nightshade grows to be around six feet tall and can be characterized by purple and green flowers, which as the name suggests, are bell-shaped. The berries are green, but quickly turn to a tantalizing, shiny black color when ripe.

That color has undoubtedly led to a number of accidental poisonings over the years. This species is said to be significantly more dangerous to children. The rumor is ingesting just two berries can be enough to kill a child. With adults the number is higher at around 10-20, but you probably still shouldn't take that chance.


Giant Hogweed

Known as Heracleum mantegazzianum in the scientific world, giant hogweed is actually native to Central Asia. But it's since spread around the world and yes, to North America. Here the toxic plant is often mixed up with the more common cow parsnip.

But giant hogweed is one plant you don't want to mess with. This is due to a phototoxic chemical compound in all parts of the plant called furocoumarin. If you get this chemical on your skin and it is exposed to light, it'll cause severe burning and blisters. The burning sensation is said to last an incredibly unpleasant 48 hours. Even after the burning is over, it's also said to cause permanent scarring.

There are rumors that if you get it in your eyes, it can cause blindness. We're not going to put that theory to the test. Unbelievably, this plant was cultivated by botanists for years and that's how it first spread to Europe and eventually North America.

Now, the toxic plant is usually listed as noxious weed in most states and is illegal to transport. The good news is this plant is easy to spot. Its main stem is often characterized by purple and red blotches and topped with huge white flowers. It can grow over 10 feet tall and nearly 5 feet across. If you find one, it might be best to report it to your state's wildlife department.


The Manchineel Tree

Hippomane mancinella, aka the Manchineel tree, is one toxic plant you never want to encounter because it can kill you in more ways than one! This tree also goes by a Spanish name that translates to "little apple of death." You can find this one in coastal areas and swamps.

So what about this tree can hurt you? Just about everything it turns out. The fruit is said to look and taste like apples at first. But then the flavor becomes more peppery in flavor and it causes gastroenteritis and internal bleeding. It'll also cause your throat to tighten up and it may kill you.

But wait, that's not all. This plant contains sap that's actually worse. It's milky-white in color and contains a natural organic compound known as phorbol. This compound causes painful blistering and burning of the skin. Standing near a burning manchineel? Don't do that, as the smoke could cause permanent eye damage including blindness.

Surely that's the worst it can get with the Hippomane mancinella, right? Wrong. Standing under a manchineel during a rain storm is just about the worst idea in the world. The sap can get washed off the leaves and rain down on you like the acidic blood of the xenomorph creatures in the "Alien" movies. Yikes.


Fortunately for North American residents., Hippomane mancinella is only found in Florida, and it's exceedingly rare. In Florida, the tree is actually listed as an endangered species. In most places, these trees are marked with a red X or other warning signs to clue people in to the fact that the innocent-looking plant standing nearby is actually the most dangerous tree in the world.